CHAPTER V.
The agent, magnetism; Its character and currents; Oxygen magnetic; Precipitation at the belt of rains occasioned by depolarization; Storms originate in this central belt and move toward the poles.
Be warned.
There was more to this introduction than meets the eye. Thanks, Opera. …
Foreword:
I got this book from Gutenberg. I have changed the grammar as far as I can manage to British English. The Gitenberg License will have to wait for a better time. The thrust of the theory is wrong but most of the arguments presented in the book, as far as I can understand them, are correct.
If the author was correct in what he knew at the time, the ideas in it are eye-opening even now150 years later. As stated in the title the book was produced in 1856. Meteorologu was in its absolute infancy in those days. It would be worth reading the major works of all the writer whom he srwas upon in his narrative as they were the founding fathers of a science that apart from developing numerical analysis to its limits has not changed a great deal since then.
Unfortunately, since he was unable to comprehend wave theory (physics too was in short trousers in the middle of the 19th century) he fell over electromagnetism as his mysterious first cause for the way that the atmosphere behaves.
Doubly unfortunate,that, as the answer to the question of “what causes weather?” is still out there -and there are only me and a few miscreants still looking.
The copies of the book found nline are supplied with graphics that are almost unusable as far as I could make out. This book would profit admirably by the use of modern satellite imagery. Unfortunately I don't have the necessary. So anyone with more pertinent cloudscapes and the like (got links anyone?) who can help out with chapters 3, 4, 6 and 7 would be most welcome.
Once I have managed to get the first few chapters online I will be translating them into modern English and doing away with as much verbiage as I can cull in the process. There is nothing the philosopher on the 18th and 19th Centuries loved more than the sight of their words in print. But unfortunately these days, most of them serve best to convince the reader that he might be better employed reading anything else, thanks very much.
Be that as it may, I would be foolish to dismiss any of the original text, so far as it can be understood, from being available as near as advisable to the original. I am after all not trying to replace the book. Any thoughts and ideas that I gain from the author I can improve upon in my own time and place.
weathercharts 
The Philosophy of the Weather, by Thomas Belden ButlerNEW YORK: D. APPLETON & COMPANY, NOS. 346 & 348 BROADWAY. 1856.Entered according to Act of Congress, in the year 1856, by T. B. BUTLER, in the Clerks Office of the District Court of the District of Connecticut.ELECTROTYPED BY THOMAS B. SMITH, 82 & 84 Beekman Street.PRINTED BY J. F. TROW, 379 Broadway.INTRODUCTION.The atmospheric conditions and phenomena which constitute “The Weather” are of surpassing interest. Now, we rejoice in the genial air and warm rains of spring, which clothe the earth with verdure; in the alternating heat and showers of summer, which insure the bountiful harvest; in the milder, ripening sunshine of autumn; or the mantle of snow and the invigorating air of a moderate winter’s-day. Now, again, we suffer from drenching rains and, devastating floods, or excessive and debilitating heat and parching drought, or sudden and unseasonable frost, or extreme cold. And now, death and destruction come upon us or our property, at any season, in the gale, the hurricane, or the tornado; or a succession of sudden or peculiar changes blight our expected crops and plant in our systems the seeds of epidemic disease and death. These and other normal conditions and varied changes and violent extremes, potent for good or evil, are continually alternating above and around us. They affect our health and personal comfort, and, through those with whom we are connected, our social and domestic enjoyments. They influence our business prosperity directly, or indirectly, through our near or remote dependence upon others. They limit our pleasures and amusements; they control the realities of to-day and the anticipations of to-morrow. None can prudently disregard them; few can withhold from them a constant attention. Scientific men and others, devote to them daily hours of careful observation and registration. Devout Christians regard them as the special agencies of an over-ruling Providence. The prudent, fear their sudden, or silent and mysterious changes; the timid, their awful manifestations of power; and they are, to each and all of us, ever present objects of unfailing interest.This interest finds constant expression in our intercourse with each other. A recent English writer has said: “The germ of meteorology is, as it were, innate in the mind of every Englishman; the weather is his first thought after every salutation.” In the qualified sense in which this was probably intended, it is, doubtless, equally true of us. Indeed, it is often not only a “first thought” after a salutation but a part of the salutation itself; an offspring of the same friendly feeling, or a part of the same habit, which dictates the salutation; an expression of sympathy in a subject of common and absorbing interest; a sorrowing or rejoicing with those who sorrow or rejoice in the frowns and smiles of an ever-changing, ever-influential atmosphere.If consistent with our purpose, it would be exceedingly interesting to trace the varied forms of expression in use among different classes and callings and see how indicative they are of character and employment.The sailor deals mainly with the winds of the hour and to him all the other phases of the weather are comparatively indifferent. He speaks of airs and breezes and squalls and gales and hurricanes; or of such appearances of the sky as prognosticate them. The citizens, whose lives are a succession of days, deal in such adjectives as characterize the weather of the day, according to their class, or temperament, or business; and it is pleasant, or fine, or very pleasant or fine; beautiful, delightful, splendid, or glorious; or unpleasant, rainy, stormy, dismal, dreadful or horrible. The farmer deals with the weather of considerable periods; with forward or backward seasons, with “cold snaps” or “hot spells,” and “wet spells” or “dry spells.” And there are many intermediate varieties. The acute observer will find much in them to instruct and amuse him and will probably be surprised to find how much they have to do with his “first impressions” of others.But I have a more important object in view. I propose to deal with “The Philosophy of the Weather”; to examine the nature and operation of the arrangements from which the phenomena result; to strip the subject, if possible, of some of the complication and mystery in which traditional axioms and false theories continue to envelop it; to endeavour to grasp its principles and unfold them in a plain, concise and systematic manner, to the comprehension of “the many,” who are equal partners with the scientific in its practical, if not in its philosophic interest; and to deduce a few general rules by which its changes may be understood, and, ultimately, to a considerable extent, foreseen.This is not an easy, perhaps not a prudent undertaking. Nor is my position exactly that of a volunteer. A few words seem necessary, therefore, by way of apology and explanation.In the fall of 1853, in the evening of a fair autumnal day, I started for Hartford, in the express train. Just above Meriden, an acquaintance sitting beside me, who had been felicitating himself on the prospect of fine weather for a journey to the north, called my attention to several small patches of scud; clouds he called them; to the eastward of us, between us and the full clear moon, which seemed to be enlarging and travelling south; and asked what they meant.“Ah!” said I, “they are scud, forming over the central and northern portions of Connecticut, induced and attracted by the influence of a storm which is passing from the westward to the eastward, over the northern parts of New England and are travelling toward it in a southerly surface wind, which we have run into. They seem to go south, because we are running north faster than they. You see them at the eastward because they are forming successively as the storm and its influence passes in that direction and are most readily seen in the range of the moon; but when we reach Hartford you will see them in every direction, more numerous and dense, running north to underlie that storm.”I had seen such appearances too many times to be deceived. It was so. When we arrived at Hartford they were visible in all directions, running to the northward at the rate of twenty-five miles an hour. In the space of forty minutes we had passed from a clear, calm atmosphere (and which still remained so), into a cloudy, damp air and brisk wind blowing in the same direction we were travelling and toward a heavy storm. My friend passed on and met the southern edge of the rain at Deerfield and had a most unpleasant journey during the forenoon of the next day. Taking the cars soon afterwards, in the afternoon, for the south, I found him on his return.“Shall I have fair weather now till I get home?” said he.“There are no indications of a storm here, or at present,” I replied, “but we may observe them elsewhere and at nightfall.”He kept a sharp look-out, and, as we neared New Haven, discovered faint lines of cirrus cloud low down in the west, extending in parallel bars, contracting into threads, up from the western horizon, in an E. N. E. direction toward the zenith.“Now, what is that?” said he.“The eastern outlying edge of a N. E. storm, approaching from the W. S. W. It is now raining from 150 to 200 miles to the westward of the eastern extremity of those bars of cirrus-condensation; perhaps more, perhaps less; and under those bars of condensation the wind is attracted and is blowing from the N. E. toward the body of the storm and where the condensation is sufficiently dense to drop rain. That dense portion will reach here and it will rain from twelve to fifteen hours hence. As we pass along the shore and run under that outlying advance cirrus-condensation, we shall see that the vessels in the Sound have the wind from the N. E., freshening but we shall continue to have this light and scarcely perceptible air from the northward for a time; the N. E. wind always setting in toward an approaching storm, out on the Sound, much sooner than upon the land.”As we approached the storm and the storm us, the evidence of denser condensation at the west and of wind from the east, blowing toward it, became more apparent. The fore and aft vessels were running “up Sound” with “sheet out and boom off,” before a fresh N. E. breeze and my friend was astonished.“I must understand this,” said he; “how is it?”“All very simple. The page of nature spread out above us is intelligible to him who will attentively study it. The laws which produce the impressions and changes upon that page, are few and comprehensible. Although there is great variety, even upon the limited portion which is bounded by our horizon, there is also substantial uniformity; and, although the changes are always extensive, often covering an area of one thousand miles or more and our vision can not extend in any direction more than from thirty to fifty, yet those changes are always, to a considerable extent, intelligible and may often be foreseen.”“Has meteorology made such progress?”“By no means. It has, indeed, been raised to the dignity of a science and professorships endowed for its advancement. Some books have been written and many theories broached in relation to it; and innumerable observations of the states of the barometer and thermometer, of the clouds and the quantity of fallen rain and the direction and force of the wind; made and recorded simultaneously in different countries; have been published and compared; and a great many important facts established and tables of ‘means’ constructed and just inferences drawn, yet the few and simple arrangements upon which all the phenomena depend and their philosophy, have not yet been clearly elicited or understood.”“Have not the ‘American Association for the Advancement of Science’ arrived at some definite and sound conclusion upon the subject?”“No; it has been with them, for many years, an interesting subject for papers and debate. Some very valuable articles, upon particular topics, or branches of the subject, have been read and published. But the Cyclonologists, as they term themselves and who seem to think the great question is, ‘Are storms whirlwinds?’ appear with new editions and phases of their favourite views as regularly as the annual meeting recurs; and, though they have not convinced, they seem to have silenced their opponents. The only conclusion, however, judging from their debates, to which the Association appear to have come with any considerable unanimity, is, that they are yet without sufficient authentic observations and well-established facts, to authorize the adoption of the Huttonian, Daltonian, Gyratory, or Aspiratory, or any of the other numerous theories which abound. And they are right. The subject is mystified by these theories and speculations of the study, founded on barometric and thermometric records and the direction and force of the surface winds.“The qualities of heat were among the earlier discoveries of science and all the phenomena of the weather were forthwith attributed to its influence. Hastily-formed and erroneous views of its power and the manner of its action in particular localities and under particular circumstances, have retained the credence accorded to them when first announced, although subsequent discoveries have shown their fallacy; some new theory of modification having been invented to reconcile the discrepancies as soon as they appeared. Perhaps it is not too much to say (however it may seem to one not thoroughly acquainted with the subject, who does not know that the primary and secondary modifying hypotheses found in Kämtz, may be counted by hundreds) that there is not remaining in any other science and possibly in all others, an equal amount of false and absurd theory and of forced and unnatural grouping of admitted facts to sustain it, as in meteorology as at present taught and received. Astronomy, as a science, is almost perfected; the nature and size and orbits, of the distant worlds around us are known; while constant changes and alternating atmospheric conditions, which all occur within less than six miles of us, affecting all our important interests and obvious to our senses, although much talked off and made the objects of many theories, are but little understood.”“How, then, did you acquire the information you seem to possess?”“By studying ‘the countenance of the sky,’ for in no other way has such information ever been, or can it ever be, acquired. By a long-continued, daily and sometimes hourly observation of the clouds and currents of the atmosphere, in connection with such reports of the then state of the weather elsewhere, as have fallen under my notice and the effect of its changes upon the animal creation; for very much can be learned from them. Yonder flock of black ducks that sit on that inshore rock, above the tide; the wildest and most suspicious of all their tribe; although the air is calm about them, know well that a storm is at hand. They probably both see and feel it. As twilight approaches they will fly away inland, forty or fifty miles perhaps and settle among the lilies or grass which surround some fresh-water pond, certain of remaining while the storm lasts and for one day at least, out of danger and undisturbed. Many a time, in my boyhood, have I heard, in the stillness of evening, the whistling of their wings, as they swept up the Connecticut valley, to seek, on the borders of the coves and in the creeks of the meadows, a concealed and safe feeding-place during a coming storm. And many a time in the autumn, after they had all passed down for the season, when the indications of an approaching storm were clearly visible at nightfall, have I waited for them to return, on the eastern margin of a bend in the cove, on the eastern side of a creek, to shoot them, though invisible, by shooting across the head of the wake, which they made upon the water in alighting and from which the few remaining rays of twilight that came from the western sky were reflected.“But I am far from being singular in this. That page is more extensively read than is generally supposed. Many plain, unassuming men; farmers, ship-masters and others within the circle of my acquaintance; know more, practically, of the weather than the most learned closet-theorist, or the most indefatigable recorder of its changes. Every one, by studying the page of nature above him, as he would the page of any other science and testing, by observation, the numerous theories invented to account for the varied phenomena, may learn much, very much, that will be useful and interesting to him and which he can never learn from books, or instruments, or theories alone.”“Well,” said my friend, “I am too far advanced in life, as are many others, to commence such observations, and you must publish.”I demurred and he insisted.“It is difficult to spare the time; and I can not neglect my profession,” I urged.“Where there is a will there is a way,” he replied.“It is difficult to make one’s self understood without many illustrations.”“Very well, they are easily obtained.”“But they cost money and it is said ‘science will not pay its way’ like fiction and humbug.”“That,” said he, “is a libel; such science will. Every one is interested in the weather; all talk about it; and thousands would carefully observe it, if they could be correctly guided in their observations.”“I may get into unpleasant controversy.”“Suppose you do; you can yield your position if wrong and maintain it if right and magna est veritas.”“But I may be mistaken in some of the views to which it will be necessary to advert, if I attempt to systematize the subject.”“Be it so; your mistakes may lead others to the discovery of the truth. Besides, the weather is common property and every one has a right to theorize about it, or to talk about it, as they please; even to call a stormy day a pleasant one, or make any other mistaken remark concerning it; and every other person is entitled to a like latitude of reply. And further,” said he, with some emphasis, “no important observation, in relation to a subject of such interest, should be lost; and, if you have observed one new fact, or drawn one new and just inference from those which have been observed by others; and especially if, from observation and reading, you can deduce from the phenomena an intelligible, observable, general system, it is not only your right but duty, to make it known. Such a knowledge of the true system is greatly desired by every considerate man.”To my friend’s last argument I was compelled to yield. I could make no reply consistent with the great principles of fraternity, which I shall ever recognize. The promise was given. My friend went on his way and I went to the daguerreotypist to procure a copy of the then appearance of the sky, as the first step toward its fulfilment. The fulfilment of that promise, reader, you will find in the following work. It was commenced as an article for a magazine but it has grown on my hands to a volume. Justice could not well be done to the subject in less space. It has been written during occasional and distant intervals of relaxation from professional avocations, or during convalescence from sickness and it is, for these reasons, somewhat imperfect in style and arrangement. But I have no time to rewrite. There is much in it which will be old to those who read journals of science but new to those who do not. There is more which will be new to all classes of readers and may, perhaps, be deemed heretical and revolutionary by conservative meteorologists; yet I feel assured that the work is a step in the right direction; that it contains a substantially accurate exposition of the Philosophy of the Weather and valuable suggestions for the practical observer.I have inserted my name in the title-page, contrary to my original intention and at the suggestion of others; for I have no scientific reputation which will aid the publisher to sell a copy. Nor do I desire to acquire such reputation. It can never form any part of my “capital in life.” Nor has it influenced me at all in preparing the work. I have aimed to fulfil a promise, too hastily given, perhaps; to put on record the observations I have made and the inferences I have drawn from those of others; to induce and assist further observations, and, if possible, of a general and connected character; and to impress those who may read what I have written with the belief, that they will derive a degree of pleasure from a daily familiarity with and intelligent understanding of, the “countenance of the sky,” not exceeded by that which any other science can afford them.I have examined, with entire freedom and fearlessness (but I trust in a manner which will not be deemed censurable or in bad taste) the theories and supposed erroneous views of others, for, in my judgement, the advancement of the science requires it. Says Sir George Harvey, in his able article on Meteorology, written for the Encyclopædia Metropolitana:“It is humiliating to those who have been most occupied in cultivating the science of meteorology, to see an agriculturist or a waterman, who has neither instruments nor theory, foretell the future changes of the weather many days before they happen, with a precision which the philosopher, aided by all the resources of science, would be unable to attain.”The admissions contained in this paragraph, in relation to the comparative uselessness of instruments and theories and the value of practical observation, are both in a good measure true. And the time has come, or should speedily come, when “pride of opinion,” and “esprit du corps,” among theorists and philosophers, should neither be indulged in, nor respected; and when their theories should be freely discussed and rigidly tested by the observations of practical men. Such measure, therefore, as I have meted, I invite in return. Let whatever I have advanced, that is new, or adopted that is old, be as rigidly tested and as freely discussed. Let the errors, if there be any; and doubtless there are; be detected and exposed. Let the TRUTH be sought by all; and meteorology, as a PRACTICAL SCIENCE, advance to that full measure of perfection and usefulness, of which it is unquestionably susceptible.
CHAPTER II.Before proceeding to an examination of this connected atmospheric machinery and an investigation of the particular ocean from which our rivers return, it may be well to look at the form in which they appear to return, that we may have a clear understanding of terms.They seem to return in the form of clouds and in storms and showers, although, in truth, they return in regular, uniform, ordinarily invisible currents and the storms and showers are but condensations in and discharges from portions of those currents, aided by the local moisture of evaporation.The term storms, seems to be used by European meteorologists to denote what we term thunder showers or gusts and tornadoes; while what we call storms are denominated by them regular rains. As the terms are extensively in use in this country, we must adhere to the meaning attached to them here rather than there.Storms with us, then, are regular rains of from six to forty-eight or more hours’ continuance: generally without lightning, or thunder, or gusts and usually with wind of more or less force, from some easterly point. They are called north-east storms, or south-east storms, according to the point from which the surface winds blow. Practically we shall find that this distinction is of some importance, for the north-east storms are the longest, lasting generally twenty-four hours, or more, while the south-east ones seldom, if ever, continue as long.These storms extend over a considerable surface, rarely less than one hundred miles in one direction or another and sometimes fifteen hundred, or more. Distinct showers cover but a small surface, sometimes not more than forty to one hundred rods, as in the tornado and rarely more than ten miles. Belts of showers, each new one forming a little more to the south, often, in summer, pass across the country, following each other in succession; and these belts may be of considerable width, say thirty to one hundred and fifty miles.The clouds which constitute the storms and showers differ in appearance and character, as well in the active as in the forming state. Clouds are of distinct characters, alike, substantially, everywhere under like circumstances; and a distinct nomenclature has been applied to them by Dr. Howard, of London. He notes three kinds of primary clouds: viz., cirrus, stratus and cumulus; and inasmuch as the boundary line between them is not very distinct, certain compounds of the three, viz.: cirro-stratus, cirro-cumulus and cumulo-stratus. This nomenclature is everywhere received and portions of it are of great practical importance.The three principal descriptions of cloud, viz.: the cirrus, the stratus and the cumulus, we have very much as they have in Europe and doubtless as they exist everywhere outside of the tropics. The nimbus, another cloud described by him, is not distinct from the cumulus or stratus. An isolated, limited thunder-shower in a clear sky, presents the appearance of a nimbus, as shown in the cuts but the basis of it is a cumulus and it differs from an ordinary fair-weather cumulus merely in the dark and fringe-like appearance of the rain as it is falling from its lower surface and sometimes in the existence of a stratus above and in connection with it. A similar form is often assumed by the peculiar clouds of the N. W. winds in March or November, when they assume the form of squalls and drop flurries of snow.The nimbus, therefore, is not a distinct cloud but an appearance which the cumulus, stratus, or cirro-stratus has in a stormy or showery state and does not deserve a distinct name. It is but a cumulus, or a stratus, or cirro-stratus dissolving in snow or rain. It is important that this term should be abandoned. It tends to confuse and prevent a clear understanding of the difference in the character of the clouds and in relation to which precision is both difficult and desirable.The figures on pages 27 and 29, show the different kinds of clouds as designated by Howard. They are copied from the engravings in the sixth edition of Maury’s “Sailing Directions.”How far these representations correspond with the actual appearance of the different compound forms in England, I can not say. But although they convey a general idea, they are not sufficiently accurate for practical illustration or observation here. Indeed Howard himself has omitted from his last edition his plate of the clouds, assigning as a reason, “that the real student will acquire his knowledge in a more solid manner by the observation of nature, without the aid of drawings and that the more superficial are liable to be led into error by them.” The collection of forms in the cuts does not contain some very important ones and contains some which are not distinct forms; but they may aid us somewhat in this inquiry, and, therefore, I have copied them. It is well, also, for the reader to have the generally received description before him.But for the purpose of practical illustration hereafter and greater precision, I shall follow a somewhat different order in describing them and introduce two forms of scud quite as important, practically, as any other.First, then, commencing at the earth, we have what may be properly termed fog, or low fog. This forms, in still clear weather, in the valleys and over the surface of the rivers and other bodies of water, during the night and most frequently the latter part of it and is at its acmé at sunrise, or soon after, limiting vision horizontally and perpendicularly and dissolving away during the forenoon. It is rarely more than from two to four hundred feet in height at its upper surface and often much less and is composed of vesicular condensed vapour, sometimes sufficiently dense to fall in mist and is doubtless in composition substantially what the clouds are in the other strata of the atmosphere, as observed by us, or passed through by aeronauts. I have never seen it carried up to any considerable height into the other strata by any of the supposed ascending currents, to form permanent clouds and shall have occasion to allude to the fact in another connection. It disappears usually before mid-day and has, when thus formed, no connection with any clouds which furnish rain.To this Dr. Howard originally gave the name of stratus and so it is represented upon the cut; but the latter term may be with greater propriety applied to the smooth uniform cloud in the superior strata from which the rain or snow is known to fall and I shall retain and so apply it.The next in order, ascending, is high fog. This is usually from one to two thousand feet in height at its lower surface. It forms, like low fog, during the night and in still weather; and is rarely, if ever, connected with clouds which furnish rain. It breaks away and disappears between ten and twelve in the forenoon, usually passing off to the eastward. This fog is most commonly seen in summer and autumn, particularly the latter and unless distinguished from cloud will deceive the weather-watcher. It is readily distinguishable. Although often very dense, obscuring the light of the sun as perfectly as the clouds of a north-east storm, it differs from them. It forms in still clear weather, is present only in the morning, is perfectly uniform, and, before its dissolution commences, without breaks, or light and shade, or apparent motion and unaccompanied by scud or surface wind. The storm clouds are never entirely uniform, or without spots of light and shade, by which their nature can be discerned and rarely, when as dense as high fog, without scud running under them and surface winds.There is another fog still, connected with rain storms but it does not often precede them; occurring at all seasons but most commonly in connection with the warm S. E. thaws and rains of winter and spring; and which usually comes on after the rain has commenced and continued for awhile and the easterly wind has abated; occupying probably the entire space from the earth to the inferior surface of the rain clouds or stratus. Practically this does not require any further notice. It is an incident of the storm. When formed it remains while the storm clouds remain and passes off with them. It is sometimes exceedingly dense in February and March, when it accompanies a thaw and if there is a considerable depth of snow, it has the credit of aiding essentially in its dissolution.Mingled with the smoke of London, it produced there the memorable dark day of the 24th of February, 1832 and at various other times has produced others of like character. (See Howard’s Climate of London, vol. iii. pp. 36, 207, 303.) These fogs have been so dense there that every kind of locomotion was dangerous, even with lanterns, at mid-day.The next in order, ascending, are the storm scud, which float in the north-east or easterly, south-east or southerly wind, before and during storms.These, as the reader will hereafter see, are, practically, very important forms of cloud condensation; although they have found no place in any practical or scientific description given of the clouds and are not upon the cuts. They are patches of foggy seeming clouds of all sizes, more or less connected together by thin portions of similar condensation, often passing to the westward, south-westward, north-westward, or northward with great rapidity. Their average height is about half a mile but they often run much lower. They are usually of an “ashy grey” colour. The annexed cut shows one phase of them, from among many taken by daguerreotype. The arrows pointing to the west show the scud distinguished from the smooth partially formed stratus above. This view was taken a few hours prior to the setting in of a heavy S. E. rain storm. It is a northerly view.At about the same height but in a different state of the atmosphere, float the peculiar fair-weather clouds of the N. W. wind. They usually form in a clear sky and pass with considerable rapidity to the S. E. Sometimes they are quite large, approaching the cumulus in form and white, with dark under surfaces and at others, in the month of November particularly, are entirely dark and assume the character of squalls and drop flurries of snow; and then resemble the nimbus of Howard. They assume at different times and in different seasons, different shapes like those of the scud, the cumulus, or the stratus.They form and float in the peculiar N. W. current which is usually a fair-weather wind and are never connected with storms. In mild weather they are usually white and in cold weather sometimes very black and at all times differ in colour from the ashy grey scud of the storm. This variety is not represented upon the general cuts. The annexed diagram shows one phase of them but they are readily observable at all seasons of the year, when the N. W. wind is prevailing; differing in appearance according to the season. Let these, as well as the storm scud, be carefully observed and studied by the reader and let no opportunity to familiarize himself with their appearance be lost. A brief glance at each recurrence of easterly or north-westerly wind will suffice.The cumuli appear in isolated clouds of every size, or in vast clouds composed of aggregated masses, as the peculiar cloud of the thunder shower. They form as low down as the scud or fair-weather cloud of the N. W. wind, which, for convenience, I will call N. W. scud; and often in violent showers and particularly in hail storms, extend up as far as the density of the atmosphere will permit them to form. Professor Espy thinks he has measured their tops at an altitude of ten miles. Others have estimated their height, when most largely developed, at twelve miles; but it is very doubtful whether the atmosphere can contain the moisture necessary to form so dense a cloud at that elevation. It is their immense height, however, whether it be six, or eight, or ten miles, together with the sudden and violent electric action, condensing suddenly all the moisture contained in the atmosphere within the space occupied by the cloud, which produces such sudden and heavy falls of rain or hail. As the rain drops or hail, when formed at such an elevation, in falling through the partially condensed vapour of the cloud must necessarily enlarge by accretion from the particles with which they come in contact and probably also by attraction, their size when they reach the earth, though frequently very considerable, is not a matter of astonishment. The cumulus is represented in the general plate with sufficient accuracy to show its peculiar character.In summer, when the air is calm, the weather warm and no storm is approaching, there is always, in the day time, a tendency to the formation of cumuli. This tendency exhibits itself about ten o’clock in the forenoon and they gradually form and enlarge until about two in the afternoon; and after that, if they do not continue to enlarge and form showers, they melt away and disappear before nightfall. Sometimes in July and August the atmosphere will be studded with them at mid-day, floating about three-quarters of a mile from the earth (in a level country), gently and slowly away to the eastward. At times it may seem as if they must coalesce and form showers, yet they frequently do not but gradually melt away, as before stated.The cumulus is the principal cloud of the tropics and is not often seen with us except in summer, or when our weather is tropical in character.The engraving on the preceding page, shows a phase of these fair-weather summer cumuli.The last in order occupying (with their compounds) the higher portions of the atmosphere, are the cirrus and stratus. The cirrus is often the skeleton of the other and precedes it in formation.These are the proper clouds of the storm, in our sense of the term. While, however, the cirrus remains a cirrus, it furnishes no rain. When it extends and expands and its threads widen and coalesce into cirro-stratus and stratus, or it induces a layer of stratus below it, the rain forms.The following is Dr. Howard’s description of cirrus: “Parallel, flexuous or diverging fibres, extensible by increase in any or in all directions. Clouds in this modification appear to have the least density, the greatest elevation and the greatest variety of extent and direction. They are the earliest appearance after serene weather. They are first indicated by a few threads pencilled, as it were, on the sky. These increase in length and new ones are in the mean time added to them. Often the first-formed threads serve as stems to support numerous branches, which in their turn, give rise to others.”The illustrations in the general cut are imperfect and do not represent the delicate fibres of the cloud, for it is a difficult cloud to daguerreotype or engrave but the representation is sufficiently accurate to give the reader a general idea of the different varieties and enable him to discover them readily by observation. They are the most elevated forms, always of a light colour and often illuminated about sunset by the rays of the sun shining upon their inferior surface; the sun, however, often illuminates, in like manner, the dense forms of cirro-stratus and the latter, from their greater density, are susceptible of a brighter and more vivid illumination.The stratus is a smooth, uniform cloud; the true rain cloud of the storm; often forming without much cirrus above, or connected with it. It may be seen in its partially formed state in the bank in the west, at nightfall, or in the circle around the moon in the night. When it becomes sufficiently condensed, rain always falls from it but in moderation. If there be large masses of scud running beneath it for its drops to fall through (especially as is sometimes the case, in two or more currents), the rain may be very heavy. But more of this hereafter.The annexed cut shows the forming stratus, light and thin, passing to the east, as indicated by the short arrows just before a storm, while the scud beneath is running to the west.It was copied from a daguerreotype view, facing northward.Intermediate between the fibrous, tufted, cirrus and the smooth uniform stratus, there is a variety of forms partaking more or less of the character of one or the other and termed cirro-stratus. No single correct representation of cirro-stratus as a distinct cloud, can be given; but several varieties will be hereafter alluded to, under the head of prognostics. Several modifications are represented with tolerable accuracy upon the cuts.The cirro-cumulus is a collection in patches of very small distinct heaps of white clouds; they are called fleecy clouds, from their resemblance to a collection of fleeces of wool and are imperfectly represented on the general cut. They do not appear often and are usually fair-weather clouds.This form has none of the characteristics of the cumulus and does not appear in the same stratum. It was probably called cumulus because its small masses are distinct, as are those of the ordinary cumulus. It occurs in the same stratum as cirro-stratus and properly belongs to that modification. I retain the name inasmuch as the cloud is of some practical importance.The cumulo-stratus is seldom seen in our climate, as it is represented in the cut. Stratus condensation above and in connection with cumulus condensation, is not uncommon but that precise form is rare.This, too, is practically of no consequence and I shall take no further notice of it.Recapitulating, I give (in a tabular form) the three principal strata and their modifications, located with sufficient accuracy for illustration. The clouds which are found in an upper or lower portion of a stratum are so represented by the location of their names; those which appear at all heights in the stratum, with the names across. The elevation is the average one; although there is no limit to the cirrus above, except the absence of sufficient moisture. It was seen by Guy Lussac and has been by other aeronauts, at an elevation of five miles, or more, when too delicate to be visible below.With the assistance of this table of elevations and a careful observation, the reader can soon become familiar with the forms of clouds and their relative situations.(Still on the easy stuff so beware.)
I thought it would struggle with that one. over 100 page downs:29 pages 254 thousand+ words and 134,384 characters with spaces.
TABLE OF CONTENTS.CHAPTER I.Heat and moisture are indispensable to the fertility of the earth; Arrangements exist for their diffusion and distribution and all the phenomena of the weather result from their operation; Heat furnished or produced mainly by the direct action of the sun’s rays; Manner in which it is diffused over the earth; Other causes operate besides the sun’s rays; The earth intensely heated in its interior; Heat derived from the great Oceanic currents and the aerial currents which flow from the tropics to the poles and from magnetism and electricity; Water distributed by an atmospheric machinery as extensive as the globe; Evidences of this; Its distribution over the continents of North America; Explanation of it; Source from whence our supply of water is derived and from which our rivers return. CHAPTER II.Our rivers return in the form of clouds and in storms and showers; Definition and character of storms; Differences in the character of the clouds which constitute them; Nomenclature of Howard; Its imperfections; New order of description; Low fog; High fog; Storm fog; Storm scud; N. W. scud; Cumulus; Stratus; Cirrus; Compounds of the two latter; recapitulation in tabular form. CHAPTER III.Our rivers do not return from the North Atlantic; All storms and showers move from the westward to the eastward; Seeming clouds seen moving from the eastward to the westward are scud; They are incidents of the storm and not a necessary part of it; The storm clouds are above them, moving to the eastward; Occasions when this may be seen; Admitted facts prove it; Investigations prove it; May be known from analogy; From the fact that there is an aerial current pursuing the same course in which the storms originate; Character of this current; Its influence upon our country; Importance of a knowledge of its origin, cause and the reciprocal action between it and the earth; To this end necessary to go down “to the chambers of the South”. CHAPTER IV.The trade wind region; Its extent and arrangements; Its belt of daily rains and movable character; The trade winds; The extra tropical belt of rains; Connection between them and their annual movements; The counter-trades; Their origin and situation; One of them constitutes our aerial current; It originates in the South Atlantic as a surface-trade; Anomalies of the trade wind region; Dry seasons; Humboldt’s description of them; Exist where the surface trades are situated; The rainless countries; Concentrated counter-trade; Monsoons; Received theory in relation to them a fallacy; Cause of the great central phenomena; Calorific theory a fallacy; Land not hotter under the belt of rains, nor sea materially so; Theory should be abandoned. CHAPTER V.The agent, magnetism; Its character and currents; Oxygen magnetic; Precipitation at the belt of rains occasioned by depolarization; Storms originate in this central belt and move toward the poles. CHAPTER VI.Course and functions of the counter-trade; Ours come from the South Atlantic; Reason why it can not come from the Pacific; Mistake of Mr. Redfield and Lieutenant Maury in regard to it; All our storms originate in it; Proofs of this; State of the weather, whether hot or cold affected by it; Proofs of this; All our surface winds are incidents of it and due to its conditions and attractions; Proofs of this; Character of the different winds; Anomalies of Mr. Blodgett accounted for; Received theory in regard to sea and land breezes a mistaken one; Proofs of this; Peculiar character of the N. W. wind; Identity with the winter Mexican northers; Character of the West India hurricanes; Of the thunder-gust; Of the tornado; Sundry particulars in relation to the latter; Due to currents of electricity; Proportions of winds in different localities; Examination of the work of Professor Coffin upon that subject; Examination of Lieutenant Maury’s theory of the monsoons. CHAPTER VII.Height of the counter-trade in different latitudes; Cause of the Calms of Cancer; Influence of mountains upon the counter-trade; Reports of Herndon and Gibbon; Focus of precipitation in the extra-tropical belt north of its southern line; Evidences of this; The elevation of the counter-trade above the earth varies in the same latitude with the variations in the phenomena of the weather; Temperature of the counter-trade; Rain dust, its origin and indications; Volcanic ashes; How far they indicate its course of progression; Question whether there is an eastern progression of the body of the atmosphere above the machinery of distribution. CHAPTER VIII.Important to understand the precise character of the reciprocal action between the earth and the counter-trade; Connection between the width and movements of the belt of inter-tropical rains and the volume of the trades; Its peculiarities over Africa, the Atlantic and South America; The magnetic equator; Character of the storms which originate in the inter-tropical belt indicate local magnetic action; Supposed influence of volcanic action; Gulf Stream changes its position; This the result of magnetic action; Alternating contrasts of heat and cold and rain and drought; Dr. Webster’s history of the weather; Spots upon the sun; Their character and influence; Cold or warm periods during the same decade and during different decades; Connection between the spots and magnetic disturbances and variations; Influence of the moon upon the weather; No decisive inference to be drawn from these facts and a more critical examination necessary. CHAPTER IX.Examination of existing theories; Calorific theory the prevailing one; Lateral overflow of Professor Dove; Absurdity of his views in relation to them; His theory of hurricanes; Its absurdity; A new theory by Mr. Dobson; Three theories advanced by meteorologists of this country; Professor Espy’s theory; Mr. Bassnett’s theory; Mr. Redfield’s theory; Extended examination of the latter; His theory in relation to the fall of the barometer contradictory in its character; Philosophy of the barometric change; No aid to be derived from these theories. CHAPTER X.Further inquiry in relation to the reciprocal action between the earth and the counter-trade; Terrestrial magnetism and what we know of it; Its elements and their variations; Their connection with the variations of atmospheric condition; Magnetism acts through its connection with electricity; Character of the latter and its variations; Their connection with atmospheric conditions; Electricity as well as magnetism in excess over this country; Effects of it upon our climate; Closer consideration of the atmospheric phenomena; Their diurnal changes and connections compared with those of magnetism and electricity; Grouping of all the diurnal variations; Particular and separate examination of them; Classification of storms; Examination in detail of the several classes and the primary influence of the earth or counter-trade in relation to each. CHAPTER XI.Prognostics.
CHAPTER III.Having thus taken a brief view of the different clouds, let us return to the inquiry, from what ocean and by what machinery, our “rivers return.”Not wholly or mainly from the North Atlantic, although it lies adjacent to us and they often seem to do so; for, first, all storms, showers and clouds, which furnish, independently, any appreciable quantity of rain to the United States and even adjacent to the Atlantic, or indeed to the Atlantic itself, come from a westerly point and pass to the eastward. This is a general, uniform and invariable law, although there is in different places and in the same place at different times, some variation in their direction; ranging in storms from W. by S. to S. S. W. and in showers between S. W. and N. W., to the opposite easterly points of the compass; the most general direction, east of the Alleghenies, being from W. S. W. to E. N. E.But do we not see, you inquire; at least those of us who live east of the Alleghenies; that when it rains, the wind is from the eastward; and that the clouds follow the wind from the east to the west?You do indeed, generally, in all considerable storms, observe that the wind blows from some easterly point and that seeming clouds are blown by it to the westward; but what you see and call clouds, are not the clouds which furnish the rain. Far above the seeming clouds you notice, directly over your head when it rains or snows, are the rain or snow clouds, dense and dark, passing to the eastward, however strongly the wind may blow from the quarter to which they tend, or any other quarter, between you and them. What you see below them are scud. So the sailors call them and so I have termed them. It is a “dictionary name,” and a good one, expressive of a distinction between them and clouds. They are thin and the sun shines through them, although with some difficulty, when the rain clouds above are absent or broken. This east wind and the scud are not the storm, or essential parts of it. Storms occasionally exist, particularly in April, without either. They are but incidents, useful but not necessary incidents, as all surface winds are.If you could see a section of the storm, you would see the rain cloud above, moving to the east and the scud beneath running to the west, as indicated by the arrows in the cut on page 40. Opportunities frequently occur when these appearances may be seen. Storms are sometimes very long, a thousand miles, perhaps, from W. S. W. to E. N. E. and not more than one to three hundred miles wide from S. E. to N. W. and their sides, particularly the northern ones, regular and without extensive partial condensation. Then the storm cloud above, moving to the eastward and the scud running under to the westward, may be seen as in the cut.So they may be seen before, at the commencement and at the conclusion of easterly storms, in a majority of cases and the reader is desired to notice them particularly as opportunities occur.The term running, too, is a very expressive one, used by sailors as applicable to scud. For while the forming or formed storm clouds may be moving moderately along, at the rate of twelve to fifteen or twenty miles an hour, from about W. S. W. to E. N. E., the scud may be running under them in a different direction; opposite, or diagonal, or both; at the rate of twenty, fifty, sixty, and, in hurricanes, even ninety miles an hour. You have doubtless seen these scud running from N. E. to S. W. and without dropping any moisture, a day or sometimes two days, before the storm coming from the S. W. reached the place where you were; and then, sometimes the storm cloud slipped by to the southward and the expected storm at that point proved “a dry north-easter.” Sometimes the condensation, although sufficiently dense to influence and attract the surface atmosphere and create an easterly wind and scud, does not become sufficiently dense to drop rain and then, too, we have a dry north-easter, which may melt away or increase to a storm after it has passed over us. I have never seen, except, perhaps, in a single instance, one of these masses of scud, however dense, which had not a rain (stratus) cloud above it, drop moisture enough to make the eaves run. So you see it may be true and if you will examine carefully, you may satisfy yourself that it is true, that the storms all move from a westerly point to the eastward, notwithstanding the wind under them is blowing and the scud under them are running to the westward.There are many other methods by which the reader may determine this matter himself. He may catch an opportunity for a view, when there is a break in the stratus cloud above and the sun or moon, no longer obscured by the storm cloud, shines through the scud beneath. Then he may see they are moving in different directions. The upper cloud, if there be any of it left, always to the eastward.Again, we may see the storm approach from the westward, as it often does, before the wind commences to blow and the scud to run from the eastward; particularly snow storms in winter and the gentle showers and storms of spring.Again, thunder storms, we know, come from the westward and apparently against an east wind. It is sometimes said they approach from the east but it is a mistake. During thirty years attentive observation in different localities, I have never seen an instance. They sometimes form over us, or just east of us, or one may form at the east and another at the west and as they spread out in forming, one may seem to be coming from the east, or there may be an easterly current, with dense flocculent scud at the under surface of the shower cloud running westward but they finally pass off to the eastward and never to the westward. It is possible that a patch of scud may become sufficiently dense and electrified to make a shower but I have never observed one. Such an apparent instance may be found recorded in “Sillman’s Journal,” vol. xxxix. page 57. I have seen the scud assume a distinct cumulus form but never to become sufficiently dense to make a thunder shower.Thunder and lightning sometimes attend portions of regular storms in spring and autumn but the thunder is always heard first in the west and last in the east.Again, there are admitted facts with which you are conversant, which prove this proposition. When it has been raining all day and just at night the storm has nearly all passed over to the eastward and the sun shines under the western edge of it and “sets clear,” as it is termed; you say that “it will be clear the next day.” Why?Because the storm will not pass to the westward, covering the sun and continuing, however strong the wind may be from the east; and because it is passing and will continue to pass off to the eastward, leaving the sky clear. The easterly wind will stop as soon as the storm clouds have passed and it will fall calm, or the wind will “come out” from the westward.So, too, when the clouds are dark in the west in the morning and the sun rises clear but “goes into a cloud,” as it is expressed, you say that it will rain. And if the clouds are dense this generally proves true; because there is a storm or shower approaching from the west and passing over to the east, the western edge of whose advance condensation has met the sun in his coming and obscured him from your vision.When, too, it has been storming and lights up in the N. W. you say it will clear off; the N. W. wind will blow all the clouds away. It is, indeed, generally true that when it so lights up it is about to clear off; although it sometimes shuts down again, in consequence of the approach of another storm from the westward, following closely behind the one which is passing off. It is a great mistake, however, to suppose the N. W. wind blows away the clouds. Watch the smooth stratus rain cloud at its lower edge, where the clear sky is seen and you will see that it is moving on steadily to the N. E., in obedience to the laws of its current and will do so, even when its retreating edge has passed up to the zenith and down to the S. E.The storm uncovers us from the N. W. by the contraction of its width, or because it has a southern lateral extension and dissolution and not by being blown away by the N. W. wind; although that wind, by its peculiar fair-weather clouds, may be, perhaps, observed beneath, ready to follow its retreating edge.Again, when it has been clear all day and the sun sets in a bank of cloud, you say; “it will rain to-morrow, the sun did not set clear,” and unless that bank is a thunder cloud, merely, which will pass over or by you, with or without rain, before morning, it is generally true that it will. The bank will prove the eastern edge of an approaching storm.From these generally admitted and understood facts, you may know that storms pass from the west to the east.This proposition is also proved by all the investigations of storms, which have taken place since the settlement of this country. Storms of great severity attract particular attention and are said to “back up” against the wind, because they are observed to commence storming first at the westward, although the wind is from the eastward. Doubtless you recollect many such instances recorded in the newspapers. No season occurs without such notices.Many storms have been investigated by Mr. Redfield, for the purpose of sustaining his theory. Many others by Professor Espy, to sustain his. One by Professor Loomis, with great research and ability; and some by others, accounts of all which have been published; and every one yet investigated, north of the parallel of 30°, has been shown to pass from a westerly to an easterly point.So, too, we may know it from analogy. The laws of nature are uniform. There is a great end to be accomplished, viz.: the distribution of forty inches of water, at regular intervals, over a large extent of country. The rivers are to return and the clouds are to drop fatness and seed time and harvest are not to cease. It is to be done and is done, by means of storms and showers and pursuant to general laws, as immutable as the result. Most of these storms and showers, it has been found and may be observed, move from the westward to the eastward. Then we may know, from analogy, that they do so in obedience to a general, uniform law; and so I might say with confidence, if our inquiry stopped here, it will ever be found by those who may hereafter examine them.But:There is a current in the atmosphere, all over the continent north of the N. E. trades but in great volume over the United States, east of the meridian of 105° W. from Greenwich; varying in different seasons and upon different parallels and flowing near the earth, when no surface wind interposes between them. In the vicinity of New York, the usual course of this current is from about W. S. W. to E. N. E. In the western and south-western portion of the United States, it is, doubtless, more southerly; varying somewhat according to the season; and in other sections varies in obedience to the general law of its origin and progress.I have observed its course in many places, between the parallels of 38° and 44° N. This current comes from the South Atlantic Ocean. It is our portion of the aerial current, which flows everywhere from the tropics toward the poles, to which I have already alluded in connection with the distribution of heat. It brings to us the twenty inches of rain which we lose by the rivers and by the westerly winds, which carry off a portion of the local moisture of evaporation and its action precipitates the remaining portion of that moisture. It spreads out over the face of our country, with considerable but not entire uniformity. All our great storms originate in it and all our showers originate in or are induced and controlled by it.From the varied action, inherent or induced, of this current, most of our meteorological phenomena, whether of wet or dry, or cold or warm weather, result; and a thorough knowledge of its origin, cause and the reciprocal action between it and the earth, is essential to a knowledge of the “Philosophy of the Weather.”Let us then go down to the “chambers of the south,” to the inter-tropical regions, of which we have said something in connection with a notice of Southern Mexico and see where and how this great aerial current originates.
That was 21 "Page Downs", some chapters are twice that lenght and more as well as being a lot harder to follow. Don't give up. If I don't I will post an easier version in a few days or years time.
No apologies for the paragraph spacing nor the quaint language. If it wasn't for the fact that language and writing styles date badly, we wouldn't have a publishing industry.
THE PHILOSOPHY OF THE WEATHER CHAPTER I.Heat and moisture are indispensable to the fertility of the earth. Without suitable arrangements for their diffusion and distribution and within the limits of certain minima and maxima, it would not have been habitable, or the design of its Creator perfected. These arrangements therefore exist and “while the earth remaineth, seed time and harvest shall not cease.” Few and simple in their character, though necessarily somewhat complicated and irregular in their operation, the ultimate result is always attained. A beautiful system of compensations supplies the losses of every apparent irregularity in one section or crop, by the abundance of others.From the operation of these few, simple, connected and intelligible arrangements for the diffusion of heat and the distribution of moisture over the earth, result all the phenomena which constitute the weather; and by studying them and their operation, we may acquire an accurate knowledge of its “Philosophy.”The necessary heat is furnished, or produced, mainly by the direct action of the sun’s rays; and the most obvious feature in the arrangements for its diffusion is that by which the sun is made to shine successively and alternately upon different portions of the earth. Nothing animate or organic could endure his burning rays, if they shone continuously or vertically upon one point, or could exist without their occasional presence. Hence the provision for a diurnal rotation, to prevent the exposure of any portion of the globe to the action of those rays for twenty-four consecutive hours, except for a limited period and at a considerable angle, in the polar regions. But the earth is spheroidal and a diurnal revolution would still leave that portion which lies under the equator too much and the other too little, exposed to the action of the sun. This is obviated by an annual revolution of the earth around the sun and an obliquity of its axis, by reason of which the northern and southern portions are alternately and, as far as the tropics vertically, exposed to the sun; and it is made to travel (so to speak) from tropic to tropic, producing summer and winter and other important phenomena.This obliquity and consequent change of exposure are in degree precisely what the wants of the earth would seem to require. If it was greater, the sun would travel further north and south but the alternate winters would be longer and more severe. If it was less, the end would not be as perfectly attained.The direct action of the sun’s rays upon the earth, particularly those portions which lie north and south of the tropics, is not the only source from which the supply of heat is derived. Although there is a general increase of heat in spring and summer when the sun travels north and of cold when he travels south in winter, yet there are frequent irregularities attending both. Very sudden and great changes occur in each of them. Frost sometimes, cool weather often, occurs in midsummer and considerable heat and tornadoes in midwinter. And ordinarily the maxima and minima of each month and, indeed, of each week are widely apart. Even in the polar regions, in midwinter, where the sun does not shine at all, the same moderating changes with which we are conversant occur in degree. An extract or two from the register found in Dr. Kane’s narrative of the “Grinnell Expedition” will illustrate this.January 1851, (Latitude about 74°, Longitude about 70°).Date. Wind. Force. Ther. Bar. Sky and Weather.Jan. 3 …… calm -26.1 29.62 blue sky, m."4 W. gent breeze -21.3 29.53 blue sky, detached clouds, m."5 W. by N. gent breeze -3.9 29.59 blue sky, m., clouded over."6 W. by S. light breeze -0.8 29.67 clouded over, m., snow."7 W. gent breeze -14.4 29.96 blue sky, detached clouds, m."8 W.S.W. light air -21.2 30.14 blue sky, m."29 W.N.W. light air -18.9 30.19 blue sky."30 NW. by W. light air -13.5 30.17 clouded over, m."31 NW. by W. gent breeze -4.4 29.35 clouded over, snow.Feb. 1 W. light breeze -11.7 29.27 cloudy, blue sky, m."2 W. light air -25.1 29.62 blue sky, detached clouds, m.These extracts are instructive. It will be seen that on the 3d of January, when the sun had been absent some weeks, it was calm, the thermometer stood at 26° below zero (the – or minus mark before the figures indicates that) and the barometer at 29.62, with blue sky, somewhat misty or hazy; (the letter “m.” standing for misty or hazy); a state of the air which existed most of the time when it did not snow or rain and therefore is of no importance in this connection. The next day the thermometer began to rise and the barometer to fall. On the 5th it clouded over and the thermometer rose rapidly and on the 6th it had risen more than 25° and snow fell. On the 7th it cleared off, the thermometer fell rapidly and the barometer rose. On the 8th the thermometer had fallen to 21° below zero and the barometer had risen to 30.14. Another instance, in all respects similar, occurred the latter part of the month. We shall see hereafter that these changes are precisely like those which occur with us and everywhere. That, as in the polar regions and whether the sun be present or absent, or obscured by clouds and by night as well as by day, the changes from warm to cold and from cold to warm are sudden and great and that the latter are connected with the fall of rain and snow; that everywhere in winter it moderates to storm.Many other instructive instances, especially in relation to the great difference in the seasons in our own country and upon the same parallels elsewhere, might be cited if it were necessary. But they will more appropriately appear in the sequel. The cause of those irregularities, especially in the same seasons of different years and when very great, is often sought and supposed to be found in the presence or absence of spots on the sun, ice floes and bergs in the Atlantic, etc., etc. But neither the spots, nor ice, nor other local causes produce them. The cause will be found in the character of the arrangements we are considering and the irregular action of the power which controls them.Nor is the temperature of the northern hemisphere, north of the tropics, equal in the same latitudes. Very great diversities exist in the “annual mean” as well as the “mean” of the different seasons. Accurate observations at many points have enabled men of science to demonstrate this by drawing isothermal lines (i. e., lines of equal average annual heat) from point to point around the earth, which show at a glance these differences. The annexed cut is a polar projection of the isothermal lines of the northern hemisphere, as far down as the tropic, copied from Kaemtz’s Meteorology. The dotted lines show the parallels of latitude, the dark lines the isothermal lines, or lines of equal annual average temperature. The reader is desired to observe how rarely they correspond with the parallels of latitude and how they fall below in a few instances and in others with great uniformity rise almost to the pole.Take, for example, the isothermal line of 0 or zero; that is, the line where the mean or average height of the thermometer for the year is at zero. At Behring’s Straits this line is a little below the Arctic circle, or the parallel of 66.30 north latitude. Passing east over North America, it descends into Canada, almost to Lake Superior and to about the 50th parallel: that is to say, it is on an average during the year as cold on our continent at the 50th parallel as it is near Behring’s Straits at the 65th parallel. Passing east, the line of zero rises again over the Atlantic Ocean until, in the meridian of Spitzbergen, it reaches, within the Arctic circle, up almost to the 75th parallel. So, too, the isothermal of 5° below zero, which is below the 60th parallel in Siberia, rises in the North Sea, above Behring’s Straits, to the parallel of 75°, descending on the continent in North America to the 55th parallel and rising again almost to the pole at Spitzbergen, to descend again in Siberia, while the isothermals of 10° and 15° below zero, which in North America are but just above the latitude of 60° and 75° respectively, ascend abruptly surrounding the magnetic pole and falling short of the geographical one. Let this projection of the lines of equal temperature and particularly the situation of the magnetic poles, be studied well, for we shall recur to it hereafter in illustration of many important portions of our subject.It is apparent from these facts and were it necessary might be rendered still more so by referring to others, that other causes operate in the distribution of heat over the earth besides the direct action of the sun’s rays upon it. Doubtless very considerable allowance is to be made for the difference of seasons and difference during the same season upon the land and upon the ocean; in mountainous countries and level ones. But making every allowance for them, the fact that other causes have a controlling influence in producing the deviations still remains most obvious. Neither the difference of temperature between the land and the ocean, or land surfaces of unequal elevations, will account for the elevation of the isothermal lines on different portions of the ocean, or their extension around the magnetic poles.Returning to a consideration of the arrangements for the diffusion of heat, we observe: First, that the earth itself is intensely heated in its interior. This is inferred and justly, from the fact that the thermometer is found to rise about one degree for every fifty-five feet of descent; whether in boring artesian wells, exploring caves, or sinking shafts in mines. It is demonstrated, also, by the existence of hot springs and the action of volcanoes. Heat is supposed to be conducted from the centre toward the surface everywhere but with difficulty and slowly. It is also supposed to be conducted from the tropical regions toward the poles. Such is the opinion of Humboldt. (Cosmos, vol. i. p. 167.)Probably it reaches the surface and exerts an influence, also, upon the weather through the ocean and by heating it in its greatest depths. Little attention has been paid, so far as I am informed, to the question how far the ocean is thus heated in tropical latitudes. Doubtless a portion of the warmth of the ocean there is derived from that source and it has its influence in changing the temperature of the [Pg 10]deep-seated cold polar currents of, the great oceans. Perhaps it may yet be found that the icebergs are detached by it in the polar seas; the observations of Dr. Kane point to such a result. (Grinnell Expedition, p. 113 and also chap. 48.)Little need be said of the inconsiderable quantities of heat supposed to be derived by radiation from the stars, the planets and from space. If any such are derived they are too inconsiderable to be of importance in this inquiry.Heat is also carried and in quantities which exert very considerable influence upon the weather, from the tropics to the poles by the great oceanic currents which flow unceasingly from one to the other.The most important of these with which we are acquainted is the Gulf Stream of the Atlantic. Gathering in the South Atlantic and passing north through the Caribbean Sea and the Gulf of Mexico, it issues out through the Bahama Channel and flows north along the eastern coast of the United States but some distance from it, to Newfoundland and from thence continuing to the north-east and spreading out over the surface of the ocean; a portion of it mingling with the waters of the North Atlantic in passing; it flows up on the western coast of Europe, around the Faroe Islands and Spitzbergen, to the polar sea; passing around Greenland and perhaps through its Fiords, it descends again through the sounds and channels of the Arctic regions into Baffin’s Bay and through Davis’s Straits, burdened with the icebergs and floes of the polar waters, to return again to the South Atlantic. For reasons which will appear in the sequel, it has comparatively little influence upon the weather of the United States. Western Europe, however, Greenland, the islands which lie in its course and the polar seas, are most materially influenced. Although not the only cause, it has very much to do with the remarkable elevation of the isothermal lines over the Northern Atlantic and upon Western Europe, as seen upon the map.A like oceanic current exists in the Pacific Ocean, the influence of which may also be traced upon the map by the elevation of the isothermal lines at the northern extremity of that ocean and upon the north-west coast of North America. A vast amount of heat is transported from the tropical to the temperate and frozen regions of the earth by these great oceanic currents.Another supply is derived from aerial currents which flow from the tropics toward the poles. These currents exist everywhere over the entire surface of the earth but in more concentrated volumes along the great “lines of no variation,” and greater magnetic intensity, on the western side of the great oceans, over the eastern portions of the two continents of North America and Asia. Not, as meteorological writers suppose, in the upper portions of the atmosphere, having risen in the trade-wind region and run off at the top toward the poles by force of gravity but near and sometimes in contact with the earth. The influence of these aerial currents upon the temperature of the atmosphere and in producing the phenomena we are to consider, is exceedingly important. We shall have occasion to examine them with great care and minuteness under another head, for upon them, more than any other portion of the arrangements, depend not only the diffusion of heat but also the distribution of moisture.Still another supply of heat, during the sudden changes, at least, is produced by the action of terrestrial magnetism and electricity. Very great progress has been made within a short period, in the investigation of the nature of these agents. The identity, or at least intimate association or connection of heat, light, electricity and magnetism, always suspected, has been in various ways and by a variety of experiments demonstrated. The influence of magnetism if distinct from gravitation, is second only to that; and its agency in producing the phenomena we are considering is primary and controlling. We will only, in this connection, ask the reader to note the situation of the north magnetic poles (for there are two of them); the manner in which the isothermal lines surround them; the fact that they are poles of cold, i. e., that it is colder there than even to the north of them. We shall recur to this part of the subject again.Such, briefly considered, are the principal arrangements by which heat is diffused over the earth.Equally marked by infinite wisdom and equally interesting and important, are the arrangements by which moisture is distributed. Doubtless the general belief is that this is a simple process; that water evaporates and rises till it meets a colder stratum of atmosphere and then condenses and falls again; or that, according to the Hutton theory, currents of air of different temperatures mingle and equalize their heat and the aggregate mass when equalized in temperature is cooler and therefore is unable to hold as much moisture in solution as the most heated portion had and the excess falls in rain. But the process is by no means so simple, nor is heat the sole or most powerful agent concerned in it. Currents of air do not mingle but stratify. evaporation from the surface of any given portion of the earth outside of the tropics does not alone supply that portion with rain. Vast and wonderful, coextensive with the globe itself and perfectly connected, is the machinery by which that supply is furnished even to the most inconsiderable portion of its surface.Take your map of North America and note, in this respect, its peculiarities. It extends from the Isthmus of Darien to the Arctic regions and from the 65th to the 160th meridian of west longitude from Greenwich and has upon its surface a type of every climate in the world. For the purpose of simplifying and illustrating the matter in hand, let us divide it into five sections. Let the first section embrace Central America and Southern Mexico, south of 28°; the second, Northern Mexico and Southern New Mexico, California, etc., between the parallels of 28° and 32°; the third, Northern California, Utah, Southern Oregon and Western New Mexico, north of the parallel of 32°; the fourth, the entire continent north of 42°; and the fifth, the eastern United States, east of the meridian of 100°. These divisions are not intended to be entirely accurate in their separation but substantially so for the purpose of illustrating the differences which exist in each.Now let us see in what a diverse manner and to what a different extent, they are severally supplied with moisture.Central America and Southern Mexico lie within the tropics; their rains are tropical rains. The season is divided into wet and dry, as are the seasons of all tropical countries which are not rainless. During the rainy season it rains a portion of nearly every day and during the dry season the sky is clear, the air is pure and rain seldom falls.All around the earth within the tropics, over the land and over the sea, there is a belt of almost daily rains, varying in width, north and south, in different sections but averaging about five hundred miles. This belt of daily rains is formed at and by the meeting of N. E. and S. E. trades and travels north and south with them, as they do with the sun, encircling the globe. By this narrow belt a portion of the earth’s surface, an average of some 35° of latitude, is supplied with moisture. Wherever it is situated at any given period, the tropical rainy season exists; and when it is absent in its northern or southern transit, the dry season prevails. Southern Mexico is within the range of this moving belt and in its course to the northward with the sun, in our summer from May to October, it arrives over and covers that country with a rainy season. When the sun returns to the south, taking with it the trades and this belt of tropical rains, that portion of Mexico is without rain and dry and so continues until the rainy belt returns in the following year. While the belt is over Southern Mexico it is nearly all precipitation and there is little evaporation; while that belt is absent it is all evaporation, with little or no rain. Surely this is not consistent with the prevailing belief of simple evaporation, ascent to a colder stratum, commingling and condensation and rain. Southern Mexico at least is not supplied by mere evaporation from its surface and must therefore form an exception to that belief and to the Hutton theory.But we shall recur again to the peculiarity of distribution within the tropics.Turn now for a brief space to Northern Mexico, Southern New Mexico and Southern California. In Northern Mexico, Southern New Mexico, Utah and California, between the parallels of 28° and 32° and particularly west of the mountain ranges, we find an almost rainless region, sterile and worthless, resembling that which is found upon nearly the same parallels of north latitude in Northern Africa, Egypt, Arabia, Beluchistan, Afghanistan and North-western India; and in corresponding latitudes south of the Equator, in Peru, a portion of Southern Africa and the northern and middle portions of New Holland. Why Northern Mexico and the other countries named are thus sterile and comparatively rainless, we shall see hereafter, when we examine critically the machinery of distribution as it operates within the tropics. It is the fact that it is thus sterile and rainless to which we desire to call attention in this place.Mr. Bartlett thus describes it:“On leaving the head waters of the Concho, nature assumes a new aspect. Here shrubs and trees disappear, except the thorny chaparral of the deserts; the water-courses all cease, nor does any stream intervene until the Rio Grande is reached, three hundred and fifty miles distant, except the muddy Pecos, which, rising in the Rocky Mountains, near Santa Fé, crosses the great desert plain west of the Llano Estacado, or Staked Plain.“From the Rio Grande to the waters of the Pacific, pursuing a westerly course along the 32d parallel, near El Paso Del Norte, there is no stream of a higher grade than a small creek. I know of none but the San Pedro and the Santa Cruz; the latter but a rivulet, losing itself in the sands near the Gila; the other but a diminutive stream, scarcely reaching that river. At the head-waters of the Concho, therefore, begins that great desert region, which, with no interruption save a limited valley or bottom-land along the Rio Grande and lesser ones near the small courses mentioned, extends over a district embracing sixteen degrees of longitude, or about a thousand miles and is wholly unfit for agriculture. It is a desolate, barren waste, which can never be rendered useful for man or beast, save for a public highway.”; Bartlett’s Personal Narrative, vol. i. p. 138.Turning now to Central and Upper California and Utah and Southern Oregon, we find still another peculiarity. Like Southern Mexico, they have a rainy and dry season but at a different period and for a different reason. The dry season of California, etc., is the summer of the northern hemisphere and her rainy season the winter. California is, therefore, dry when Southern Mexico is wet and vice versâ. The belt of rains which supplies California with moisture during her rainy seasons is the belt of extra-tropical rains, which extends from the northern limit of the north-east trades to the poles, encircling the earth. The southern edge of this extra-tropical belt is carried up on the western coast of America and in that portion of the continent in summer, when the sun and trades and the inter-tropical rainy belt travel to the north and uncover California, etc., leaving them without rain for a period of about six months.As the sun, with the trades, travels south, the southern edge of the belt of extra-tropical rain follows and covers California, etc., again extending gradually from the north to the south and thus their wet season returns. The annexed diagrams by the shading will show the situation of the rainy belts which cover Mexico, Utah, New Mexico and California in summer and winter and that the belts of rains are entirely distinct and different in character.Here again in this section of the continent, as in Mexico, evaporation is going on for six months of the year, and were it not for the return of the belt of rains from the north, in the fall, would go on for the entire year without precipitation; and for the other six months precipitation is vastly in excess. Nor can this be reconciled with, or explained by, Hutton or any other received theory of rain. Here again it is obvious that evaporation alone, however great or long continued, will not furnish the evaporating section with rain.The northern portion of the continent lies beneath the zone of extra-tropical rains and north of the northern limit of the N. E. trades; is never uncovered from it and has no distinct rainy or dry season, although more rain falls at certain periods and in certain localities, than at others. The climate of that part of Oregon which lies upon the Pacific and the character of its rains, resemble those of North-western Europe and will be further explained hereafter.Coming to the portion of the continent which we occupy, the 5th section, we find it different still; a most favoured region. Portions of it; Eastern Texas, for instance; are upon the same parallels of latitude as the rainless regions of Northern Mexico, etc. Eastern Texas, however, is not rainless. Other portions are upon the same parallels as California, etc., yet have no distinct rainy and dry season. We repeat, this section is a most favoured region; without a parallel upon any portion of the earth’s surface, except, in degree, in China and some other portions of Eastern Asia.It is not only without a distinct rainy and dry season but it is watered by an average, annually, of more than forty inches of rain, while Europe, although bounded on three sides by seas and oceans and apparently much more favourably situated, receives annually an average of only about twenty-five; if we except Norway and one or two other places, where the fall is excessive. The distribution of this supply of moisture over the United States is, in other respects, wonderful. Iowa, in the interior of the continent, far away from the great oceans, on the east or west, or the Gulf of Mexico on the south, receives fifty inches; some ten or fifteen inches more than fall upon the slope east of the Alleghenies and contiguous to the great Atlantic (from which all our storms are, erroneously, supposed to be derived) and the average over the entire great interior valley is about forty-five inches, falling at all seasons of the year.Observe, then, by way of recapitulation: Southern Mexico has a rainy season furnished by the belt of inter-tropical rains, which travels up over it from the south in summer. California has a rainy season, which is furnished by the extra-tropical belt of rains, which travels down from the north and covers it in winter. Northern Mexico and the adjoining regions west of the 100th meridian are between the limits of the two and neither travels far enough to reach them, except for brief and uncertain periods; they are comparatively rainless; while the eastern portion of the continent, in all latitudes, unlike the others, is without a distinctly marked dry season, or a rainless region and with the exception of occasional droughts, is abundantly supplied with rain at all seasons of the year.And now, what is the explanation of all this?What produces the extra-tropical belt of regular rains surrounding the earth, north of the parallel of 30° north, in some places and 35° in others, extending to the pole, with its southern edge travelling up ten or more degrees in summer, leaving large portions of the earth subject to a dry season; and back again in the winter to give them a rainy one?What produces the narrow belt of inter-tropical rains, encircling the earth; travelling up and down every year over an average of 35° of latitude, supplying every portion of it alternately with rain?And what connects the two together over the eastern portion of North America, so as to leave no distinctly marked wet and dry season and no rainless and sterile portion there?Are all these the result of simple evaporation, ascent to a colder region, condensation and descent again?Demonstrably not. Of the forty inches which fall annually upon the middle and eastern portions of the United States, an average probably of one-half or twenty inches, runs off by the rivers to the ocean, or is carried away eastward by the westerly and north-westerly evaporating winds. The same is true, in degree, of the rain which falls upon the other portions. evaporation, therefore, could not keep up the supply. From whence, then, does it come this twenty inches, thus lost by the rivers and winds and with such wonderful regularity every year?“All the rivers run into the sea, yet the sea is not full. Note the place whence the rivers come, hither they return again.”But how is it that they thus return with such wonderful regularity, in a narrow travelling belt of daily rains within the tropics and a movable belt of irregular rains without the tropics, extending to the poles, leaving a space on each side of the equator encircling the earth in like manner (except at two points, viz., Eastern Asia and Eastern North America), from which they do not go and to which they do not return and which is almost entirely unfurnished with rain?And all this without any relation, whatever, to the contiguity of the oceans?Obviously this is not the work of mere evaporation, or of the accidental or irregular commingling of winds with different dew points, or quantities of moisture in solution, or accidental, irregular changes of barometric pressure. It is one vast, wonderful, connected and regular system; co-extensive with the globe; necessary to the return of moisture from the oceans upon the most inconsiderable portion of it and to the condensation of the local moisture of evaporation; and by it the waters are returned from the oceans as regularly and bountifully upon the far interior of the great continents in the same latitudes, as upon the “isles which rest in their bosoms.”
The same is probably true of the interior of the country everywhere. Lieutenant Maury, in the course of his investigations and in order to ascertain the direction of the winds in the Mississippi valley during rain, addressed a number of gentlemen and received their replies, which are published with his wind and current charts. Several answered, among other things, that, “whenever the lightning appears to linger at the north at eventide, rain almost invariably follows speedily; not so in the south.” Thus it frequently is with us. If, during a hot, dry time, of a few days continuance, the lightning so lingers in the evening and the wind continues to blow fresh from the southward after nightfall, showers will generally follow within forty-eight hours, most commonly the next day and a cool N. N. W. or N. W. wind with a favorable change ensue. Such, at least, has been the result of my observation for many years.Indeed this seems to be the general law in summer in the Mississippi valley, where the easterly winds are not so common as with us. To illustrate this further, I copy from a recent work by T. Bassnett, entitled the “Mechanical Theory of Storms,” two short extracts, showing the manner in which belts of showers extend southerly, while progressing north-eastwardly, at Ottawa. The first occurred in August, 1853; the last, December, 1852. The first was a belt of showers; the latter would have been in August but the lateness of the season changed its character somewhat, though not entirely, to a more regular rain, especially toward the close.“August 6th.; Very fine and clear all day: wind from S. W.; a light breeze; 8 P.M. frequent flashes of lightning in the northern sky; 10 P.M., a low bank of dense clouds in north, fringed with cirri, visible during the flash of the lightning; 12 P.M., same continues.“7th.; very fine and clear morning; wind S. W. moderate; noon, clouds accumulating in the northern half of the sky; wind fresher, S. W.; 3 P.M., a clap of thunder over head and black cumuli in west, north and east; 4 P.M., much thunder and scattered showers; six miles west rained very heavily; 6 P.M., the heavy clouds passing over to the south; 10 P.M., clear again in north.“8th.; Clear all day; wind the same (S. W.); a hazy bank visible all along on southern horizon.“December 21st, 1852.; Wind N. E., fine weather.“22d.; Thick, hazy morning, wind east, much lighter in S. E. than in N. W.; 8 A.M., a clear arch in S. E. getting more to south; noon, very black in W. N. W.; above, a broken layer of cirro-cumulus, the sun visible sometimes through the waves; wind around to S. E. and fresher; getting thicker all day; 10 P.M., wind south, strong; thunder, lightning and heavy rain all night, with strong squalls from south.“23d.; Wind S. W., moderate, drizzly day; 10 P.M., wind west and getting clearer.”It is obvious that the showers at the north passed east on the evening of the 6th of August; that new showers, taking the same course, originated in the north but more southerly next day, with S. W. wind and that they passed east and others formed successively further south, which passed over the place of observation late in the afternoon and that others formed south and passed east during the night and next day, visible in a bank on the southern horizon.Later or earlier in the spring and autumn, these brisk afternoon southerly winds continuing after nightfall, indicate moderate rains from a rainy belt extending in a similar manner, without the cumuli and thunder which attend those of mid-summer. I shall recur to this class of showers and storms when we come to their classification.Light surface winds from south-west to west are not often storm-winds and are usually those which the trade near the earth draws after it. Sometimes the trade seems to draw the surface wind from the S. W. and W. S. W. with considerable rapidity and some scud a little distance above the earth. When this is so, it will be found that a storm has passed to the north of us, or a belt of rains is passing north, which may or may not have sufficient southern extension to reach us. When there have been heavy storms at the south in the spring, especially if of snow, the S. W. wind which the trade draws after it and which comes from the snowy or chilled surface, is exceedingly “raw”; that is, damp and chilly, although not thermometrically very cold. Probably every one has noticed these “raw” S. W. winds of spring.Usually, when storms and showers, which have not a southern lateral extension, pass off, the trade is very near the earth and a light S. W. wind or calm follows for a longer or shorter period. Not infrequently, however, our N. E. storms terminate with a S. W. wind, shifting suddenly, perhaps, just at the close of the storm, during what is sometimes called a “clearing-off-shower,” or, more frequently, dying gradually away as a N. E. wind and coming out gently from the S. W., following the retreating cloud of the storm. In such cases it is said to “clear off warm.”With us the wind rarely blows from the west, except while slowly hauling from some southerly point to the N. W. It is probably otherwise east of the lakes and in some other localities to the north-west.Occasionally and most frequently in March, a W. to W. N. W. wind follows storms and blows with considerable severity, with large irregular, squally masses of scud and sometimes a gale. Such was the character of the dry gale which crossed the country, particularly Northern New York, in March, 1854, doing great damage. These westerly winds are always accompanied by a continued depression of the barometer and peculiar, foggy, scuddy, condensation and should be distinguished with care from the regular and peculiar N. W. wind, as they may be, by the continued depression of the barometer and the character of the scud. They are doubtless magnetic storms.The remaining surface wind, the N. W., the genuine Boreas of our climate, the invariable fair-weather wind, is one of great interest. It is unique and peculiar. It is not the left-hand wind of a rotary gale and has no immediate connection with the storm. I have known it blow moderately, fifteen successive days in winter; rising about ten A.M. and dying away at nightfall. Occasionally but very rarely indeed, a light wind exists from the N. W. during a storm, owing probably to a focus of intensity in relation to some surface the storm covers, like the focus which exhibits itself as a clearing-off shower near the close of a storm; but the real fair-weather Boreas is a different affair altogether. Let us observe with care its peculiarities; they are instructive.1st. It rarely blows with any considerable force beneath the trade while there are storm clouds, or any considerable condensation in it. It does not interfere with that reciprocal action which takes place between the trade and the earth, during approaching or existing storms. I have frequently seen it with its peculiar scud clouds in the N. W., waiting for the storm condensation of the trade to pass by, that full of positive electricity it might commence its sports; rushing and eddying along the surface, licking up the warm, south polar, electric rain, which stood in pools upon the ground, or rose in steamy vapour from the surface and with its cool breath dry up the muddy roads as no degree of heat can dry them.The annexed figure (14) shows the appearance of the northern edge of a stratus storm cloud, passing off E. N. E. at the close of the storm, which was “clearing off from the north-west.” It is from a daguerreotype view, looking W. N. W., taken at eight o’clock in the morning, in the fall of the year. Near the horizon maybe seen the N. W. scud, forming in the N. W. wind, which is about to follow the retreating edge of the storm cloud.Figure 15 is from a daguerreotype view, taken at eleven o’clock the same day, when the storm cloud had passed off and its edge remained visible only south of the zenith and the north-east scud had risen up and covered the northern half of the sky and the wind was blowing a gale from that quarter.Another view was taken about two P.M. of the same day, when the scud had a very dark, gloomy appearance; as dark and gloomy as those of a Mexican norther; too dark to represent by a cut.Not infrequently in a moist summer season, after a day of showers or rain, which have had an extending formation or lateral extension from north to south, it will commence blowing in the morning and encourage the hay-maker with the hope of fine weather. But often before noon, the milky stratus condensation above with cumuli below, will appear in the trade; the N. W. wind die away and variable airs from the east or south appear, to be followed toward night by an enlargement of the cumuli and showers. It rarely, if ever, blows fresh till the storm condensation of the trade has passed; or continues to blow after that condensation reappears. When it commences blowing after a storm and the northern edge of the storm is not over us, we may frequently see the latter low down in the S. E. passing eastward.2d. Its scud are peculiar. Every one, probably, has noticed them. They are distinct, more or less disconnected, irregular, with every form between those of the easterly scud, cumulus and stratus, according to the season. If large, with dark under surfaces; forming rapidly and as rapidly dissolving; rarely dropping any rain, sometimes dropping a flurry of snow, in November or March, oftener than at any other period; sailing away to the S. E. and casting a travelling shadow as they pass on over the surface of the earth. Their electricity, particularly when white, is probably always positive, as that of all whitish clouds is supposed to be.3d. It is emphatically a surface wind. The incident storm winds, the N. E. and S. E., frequently commence blowing under the storm, toward its point of greatest intensity, up near the line of cirro-stratus condensation, evidenced by the running scud; or blow there with most rapidity and so continue for hours before the whole surface atmosphere from thence to the earth becomes involved in the movement; and sometimes without being felt below at all. Not so with the N. W. wind; it begins at the surface and blows there with more rapidity than above; it seems to be attracted by the earth; it interposes between the earth and the trade, wedging the trade up and occupying its place. It blows under at all seasons of the year but most readily and strongly from a surface of snow whose electricity is always positive. Hence it blows most strongly and continuously when snow has fallen at the north and prevails during winter very much in proportion to the extent and continuance of the covering of snow which invests the earth in that direction. It follows after storms and particularly warm rains, during the autumn, winter and spring months, which have a lateral southern extension. Whether it is increased by the snow from the surface from which it blows, or is caused by the same magnetic action which causes the great fall of snow, is a question we shall consider hereafter.4th. It does not connect or mingle with the trade current in any way, or change or divert the course of that current; but interposes between it and the earth, elevating the trade in proportion to its own volume, above the influences of the earth (when the trade becomes free from condensation and singularly, clear); and raising proportionately the barometer. An experienced observer can frequently estimate, with considerable accuracy, the rise of the barometer, by measuring with his eye, (when the clouds will enable him to do so,) the depth of this interposed N. W. current. The barometer rarely rises after a storm, for twenty-four or forty-eight hours if the wind continues at any point from S. W. to W. N. W. but always rapidly as soon as the genuine N. W. current with any considerable depth interposes and elevates the trade.It will be obvious to every one, I think, certainly, if they will hereafter study the subject and observe for themselves, that the N. W. wind does not blow away the storm; and that it follows after it, blowing over the surface which is uncovered by the storm; rarely, if ever, with any force when the body of the storm passed south of us; and that it is a purely surface wind, seemingly attracted by the peculiar magneto-electric state in which the surface of the earth is left, compared with a snow-clad surface to the north, by a recent storm, or that peculiar state of the trade which is left by the action of the storm. It seems to follow that magnetic wave which, passing from north to south, acts in its course upon the counter-trade, producing the storm, or belt of showers and giving them their southern lateral extension and will well repay future telegraphic investigation. Its electricity is intensely positive; that of the earth by the action of the storm as intensely negative.5th. This N. W. wind occurs in all parts of the northern hemisphere, so far as we have data to determine and its corresponding wind from the S. W. occurs in the southern hemisphere. It is identical with a class of the northers of the Gulf of Mexico, as a brief analysis of the character of the latter will show.1st. The fall and winter norther is a dry wind without rain or falling weather; so is our N. W. wind.2d. It is preceded by a falling barometer; S. E. scud and rain at the point where it blows, or to the eastward of it. So is ours when it blows a gale in the fall and spring months, which bear the nearest resemblance in climatic character to the periods when the northers blow. With this distinction, however, that our precedent rains either pass over us or to the southward, the direction of storms being E. N. E.; their precedent storms passing over or to the eastward of them as they move more to the northward.3d. It is often preceded by a copious dew; so is ours; such dews often following light fall rains in our climate and preceding N. W. wind.4th. The most peculiar characteristic, however, is that the barometer rises rapidly and invariably while the norther prevails and very much in proportion to its violence. The same is true of our genuine N. W. wind and is not true of any other wind on this continent which I have observed or read of.5th. While they are thus alike in these respects, they are unlike in no respect.Mr. Redfield has traced them in supposed connection with storms which continue from that vicinity across the United States to the E. N. E. and endeavoured to connect them with those storms, as the left-hand winds of a rotary gale. Obviously, I think, they are identical with our N. W. winds which also follow, indeed but are distinct from the storms.There are a class of northers in the Gulf of Mexico; the “Nortes del Muero colourado”; sometimes occurring in the summer months, beginning at N. E., veering about and settling at N. N. W. and as they decline hauling round by the west to the southward. These winds correspond precisely with the hurricane winds of the West Indies and are doubtless the incident winds of a storm travelling thence to the N. N. W. precisely as our N. E. or E. N. E gales are incident storm winds to the N. E. storms of our latitude.In this connection we will look at the peculiarities of a West India hurricane.“It is not a little remarkable,” says Mr. Espy, speaking of the storms and hurricanes of the West Indies, “that all these storms and all others which have been traced to the West Indies, travelled N. W. almost at right angles to the direction of the trade-wind in those latitudes but very nearly, if not exactly, in the direction of an upper current of the air known to exist there toward the N. W.” Substantially the same facts have been repeated by Mr. Redfield and demonstrated by his able investigations, both there and in the Eastern Pacific and are confirmed by the observations of Edwards, Lawson and others, while residents there. It is a matter of surprise that gentlemen like Messrs. Redfield and Espy, who have certainly displayed great ability in the investigations of meteorological phenomena, should fail to recognize a more intimate relation between this upper current and the storms they were investigating and to detect the general laws which govern both. The storms and hurricanes of the West Indies are comparatively of small diameter and have little advance condensation. When they pass on to the south-western portion of North America and curve to the N. E., as they frequently do, they enlarge in front and at the sides and their advance condensation, which is not dense enough to drop rain, extends in some cases from one to three hundred miles; and the storm itself, by the time it reaches the Alleghenies, may extend one thousand to fifteen hundred miles and perhaps in certain magnetic states of the surface and occasionally, may cover the entire portion of the continent, from north to south. Such, probably, was very nearly the extension of the storm investigated by Professor Loomis. In the West Indies, however, at the commencement, they vary from twenty to one hundred miles, or possibly more, in width.First, they are preceded by a hot, sultry and oppressive atmosphere; as are electric storms everywhere; a peculiar electric state of the earth and adjacent air.Second, the black clouds and lightning which indicate the approaching hurricane are seen to the S., S. E. and E. S. E., according to the season of the year, as we see them at the westward. During the rainy season and when the storm, as is usual at that period, is small and the S. E. trade blows more eastwardly, the wind at the Windward Islands, possibly, may set in at the north and back round by the east as it progresses. So Colonel Reid thinks it sometimes does, at Barbados. But when the belt of rains is south and the hurricane comes from the south-east and is larger and more violent in its action and the north-east winds prevail, the first effect is an increase of these trades. Soon, however, the wind hauls to the north and north-west, in opposition to its course, bearing the same relation to it that our east and north-east winds bear to storms in the United States; and the wind hauls around during the passage of the storm to the west, south-west and south-east and at the latter point it clears off. Mr. Edwards in his History of Jamaica says; and as a resident, his authority should be decisive as to this Island; “that all hurricanes begin from the north, veer back to the W. N. W., W. and S. S. W. and when they get around to the S. E. the foul weather breaks up.” Doubtless the same is true of the class of northers of which we are speaking on the Gulf of Mexico. But with this class the barometer does not rise during the gale and in proportion to its length and violence. With the other class of N. W. winds; the northers of winter; it does.The following description of two winter northers, copied from Colonel Reid’s valuable work, will illustrate what has been said. Precisely such changes from S. E. rains to N. W. winds, with blue sky and detached dark clouds; fair-weather N. W. scud; occur every autumn in October and November and the falling of the thermometer and rising of the barometer, after rain and a change of the wind, are perfectly characteristic.1843. Wind. Force. Weather. Bar. Ther. Jan. 30. A.M. 4. S. S. W. 2 b. c. 29.90 77 Off Tampico.Noon. South. 5 b. c. r. 29.86 76 Lat. 23° 41′ N., Long. 94° 50′ W.P.M. 8. South. 6 b. c. r. 29.84 76 Jan. 31. A.M. 4. S. Easterly. 3 b. c. 29.90 74 Between 6 and 10 A.M., wind was variable.Noon. N. by W. 9 c. q. w. 29.96 76 Norther commenced at 10 A. M.P.M. 8. N. N. W. 9 c. 30.09 73 Lat. 22° 36′ N., Long. 95° 48′ W.Feb. 1. A.M. 4. N. N. W. 7 c. g. 30.29 63 Lat. 22° 9′ N., Long. 94° 50′ W.Noon. Westerly. 6 c. 30.03 67 P.M. 8. Calm. 0 c. 30.26 67 Feb. 14. A.M. 4. S. E. 3 b. c. r. 29.66 73 At Sacraficios.Noon. S. W. 4 b. c. 29.62 Norther comc’d at 5.30 P.M.P.M. 8. N. W. by N. 10 c. q. u. 29.72 65 Feb. 15. A.M. 4. N. W. by N. 10 c. q. u. 30.10 61 Gale moderated and again freshened about 8 A.M.Noon. N. W. by N. 10 c. g. q. 30.19 61 P.M. 8. N. W. 4 c. g. 30.20 65 Feb. 16. A.M. 4. N. W. 3 q. 30.18 62 P.M. 8. N. N. W. 2 c. g. 30.21 66 b. indicates blue sky; c. detached clouds; r. rain; v. visibility of objects; q. squalls; w. wet dew; u. ugly threatening appearance; g. gloomy weather.The exact counterpart of the first norther may be observed with us every fall. On the 30th January, with a rising thermometer and falling barometer, there was rain at midday. The night following was moist; the next day, about ten A.M., the wind came out N. W., with squalls and gloomy weather, a falling thermometer and rising barometer.The norther of Feb. 14th differed from the other only in regard to the time of the day when it commenced; the order of events was the same. The rain fell in the night; it cleared off early in the day and the norther followed in the afternoon. This also is frequently the case with us, as every one may observe.This brief notice of the surface winds of our climate would be incomplete without a description of those of the thunder-gust and tornado.The former is exceedingly simple. The showers, which are accompanied with much wind, form suddenly in hot weather and have a considerable advance condensation (frequently with obvious lateral internal action), extending eastwardly from the line of smooth cloud from which the rain is falling, or rather where the falling rain obscures the inequalities of the cloud. The gust is never felt until the advancing condensation has passed over us, when it takes the place of the gentle easterly breeze which previously set toward the shower. The gust ceases as soon as the cloud has passed. It is obviously the result of the inducing and attracting influence of the cloud upon the atmosphere near the surface of the earth as it passes over it. Let the reader watch attentively this advance condensation, from its eastern edge to the line of smooth cloud and falling rain and he will understand at a glance this internal action of gust-clouds. The whole phenomena are simple and intelligible. A cloud approaching from a westerly point, dark and irregular from its eastern edge to the line of falling rain, where it appears smooth and of a light colour; wind from the east blowing gently toward it, till the condensation is over us; then the gust following the cloud; then the rain and in a few minutes the cloud and wind and rain have passed on to the east and “sunshine” returns.The tornado, as it is termed when it occurs upon land, “spout,” if on the water, is sometimes of a different character and as it undoubtedly had great influence in inducing the gyrating theory of Mr. Redfield and the aspiratory theory of Mr. Espy and has been cited by both in support of their respective theories, it deserves a more particular notice. There are several marked peculiarities attending it which determine its character.1st. It occurs during a peculiarly sultry and electric state of the trade and surface atmosphere and at a time when thunder showers are prevailing in and around the locality and at every period of the year when such a state of the atmosphere exists. One recently occurred in Brandon, Ohio, in midwinter.2d. There is always a cloud above but very near the earth, between which and the earth the tornado forms and rages. It is usually described as a black cloud, ranging about 1000 feet or less above the earth, often with a whitish shaped cone projecting from it and forming a connection with the earth; at intervals rising and breaking the connection and again descending and renewing it with devastating energy. Its width at the surface varies from forty to one hundred and eighty rods; the most usual width being from sixty to ninety rods. Sometimes when still wider, they have more the character of thunder-gusts and are brightly luminous.3d. Two motions are usually visible, one ascending one near the earth and in the middle and a gyratory one around the other. The latter is rarely felt, or its effects observed, near the earth. Occasionally and at intervals, objects are thrown obliquely backward by it.4th. It is composed, at the surface of the earth, of two lateral currents, a northerly and southerly one, varying in direction but normally at right angles in most cases, although not always, with its course of progression, extending from the extreme limits of its track to the axis; which currents are most distinctly defined toward the centre and upward. These currents prostrate trees, or elevate and remove every thing in their way which is detached and movable. There does not seem to be any current in advance of these lateral ones tending toward the tornado, save in rare and excepted cases and then owing to the make of the ground or the irregular action of the currents; nor any following, except that made by the curving of the lateral currents toward the centre of the spout as it moves on and perhaps a tendency of the air to follow and supply the place of that which has been carried upward and forward, like that of water following the stern of a vessel. The south current is always the strongest and often a little in advance of the other and covers the greatest area. The proportion of the two currents to each other is much the same that the S. E. trades bear to the N. E. This excess in volume and strength of the southerly current will explain the irregularities in most cases and the fact that objects are so often taken up and carried from the south to the north side and so rarely from the north and carried south of the axis. These irregularities are such as attend all violent forces and something can be found which will favour almost any theory; but the two lateral currents appear always to be the principal actors, except, perhaps, when it widens out and assumes more the character of a straightforward gust. See a collection by Professor Loomis, American Journal of Science, vol. xliii. p. 278.
CHAPTER IV.Between the parallels of 35° north latitude and 35° south latitude; changing its location within this limit at different seasons of the year; encircling the earth and covering about one-half of its area; we find the trade-wind region. In this region are the simple and uniform arrangements, which extend everywhere and produce all the atmospheric phenomena. In the centre of it we find that movable belt of continual or daily rains and comparative calms, particularly near its centre, about four hundred and fifty miles in width upon the Atlantic and over Africa and the eastern portions of the Pacific and something more over South America and the West Indies, the western portion of the Pacific and the Indian Ocean, to which we have already alluded.This belt of rains and calms follows the trades and sun, in their transit north and south, from one tropic to the other; its width and extension depending upon the volume of trade-winds existing on the sides of it. Its southern edge, when the sun is at the southern solstice, extends to 7° south in the Atlantic, to 10° south in the Indian Ocean and still further, probably, over South America: on this point I do not pretend to be accurate, for accuracy is not essential. When the sun is at the northern solstice the southern edge is carried up as far as 12° north, over the Atlantic and still further over the northern portions of South America, the West Indies and Mexico. It travels, therefore, from south to north, over from twenty to forty degrees of latitude. The presence of this belt of rains over any given portion of the inter-tropics, gives that portion its rainy season and its absence, as it moves to the north, or the south, gives the portion from which it has moved, its dry season. It passes in its transit twice each year over some portions of the country, Bogota, for instance and two corresponding rainy and dry seasons result. Its presence and character and movements, are as fixed and regular, over from twenty-five to forty degrees of the earth’s surface and all around it, as the presence and movements of the sun over the same area.At the northern edge of this movable belt of rain and extending in some places, particularly in the Pacific Ocean, north about 20°, or about one thousand four hundred miles and in other places a less distance, the N. E. trade winds prevail, blowing toward and into it from N. N. E., N. E. and E. N. E., averaging about N. E. At the south line of this belt of rains, extending south from twenty-five to thirty degrees, or from sixteen hundred to two thousand miles, the S. E. trades blow toward and into it, from the S. E., S. S. E., or E. S. E., averaging about S. E. Of course the northern limit of the N. E. trades travels north and south with the belt of rain, toward which it blows; and so the southern limit of the S. E. trades travel in like manner with the rainy belt, or rather, to speak with entire accuracy, the belt of rain moves with the trades and the trades follow the verticality of the sun. The following diagrams exhibit approximately and with sufficient accuracy for illustration, the situations of the rainy belt and the trades, when at their northern and southern limit, as well as the manner in which it must give certain localities two rainy seasons each year, in its transit north and south.At the northern and southern limits of the trade-winds and extending from them to the poles, are found the variable winds and irregular extra-tropical rains, all over the earth, which are shown by the shading on the maps. This line of extra-tropical rains descends to the south, following the retreating trades as they descend in our winter and recedes north before the trades when they return in spring and summer, so that at the outer limit of the trades respectively, toward the poles, the line of extra-tropical rains will be found, receding or following that limit, as the trades pass up and down with the sun. From the north pole to the northern limit of the N. E. trade-winds, wherever found, whether at 38° north latitude, as in some places in summer when the sun is at the tropic of Cancer; or whether at 20° to 30° north latitude, as in our winter, when the sun is at the tropic of Capricorn; the extra-tropical rains prevail. A state of things precisely similar exists between the south pole and the southern limit of the S. E. trades. Between this northern limit of the N. E. trades and the northern line of the inter-tropical belt of rains, wherever situated (with two exceptions, to which we have alluded and shall allude again), there is, for the time being, a dry season; and a like dry season between the southern line of the belt of rains and the southern limit of the S. E. trades. We have, therefore, extending around the earth, a belt of daily tropical rains, near the centre; two belts of drought which are mainly trade-wind surfaces, one on each side of the central rainy belt; extending to the outward limits of the trades and the line of extra-tropical rains; and these rainy and dry belts, moving up and down after the sun, a distance of from twenty to forty degrees of latitude, each year.Such are the main phenomena, at the surface, in the trade-wind region. Ascending a step higher in the atmosphere, we find, above the surface-trades, a counter-trade, running, not in the opposite direction but at right angles, or nearly so. The counter-trade which issues from the northern side of the rainy belt, running to the N. W. or W. N. W. and the counter trade which issues from the southern side, running to the S. W. or W. S. W., varying, as the trades do in direction in different localities. These counter-trades are continuations of the surface trades, which, ascending in their course, have threaded their way through the opposite trade in the rainy belt and are continuing on at the same angle and in the same direction at which they blew upon the surface and in obedience to the same law. This is apparent from several considerations.They issue at the same angle and over the top of the surface trades. In the West Indies and elsewhere, this has been ascertained and proved by the course of the storms and the rotation of their surface winds and observation.>>>>>>>We can not suppose the N. E. trade to be reflected and turn back over itself at a right angle. That would be impossible, even if there were a wall of solid material there for it to blow against. Air is a peculiar fluid and it stratifies with astonishing ease. He who supposes that a current of air put in motion can be turned aside by another current, or by the atmosphere at rest, or can be made to mingle, is mistaken. It will stratify and force itself onward through the adjacent and opposing atmosphere and in a right line. I have observed some remarkable instances of this character.<<<<<<<The cause which operates to produce the surface trades, still operates upon the current to carry it over into the other hemisphere; a counter-trade, as we shall see. It is impossible, therefore, to believe that the surface-trades as they arrive at the belt of rains and calms, turn at a right angle, or at any angle and return: and impossible to doubt that they pass through each other in this belt and out at the opposite side, as upper currents, at the same angle at which they entered. Of course the N. E. trade of the Atlantic becomes the N. E. counter-trade of South America, carrying their storms in a S. W. direction and the S. E. trade of the Atlantic the S. E. counter-trade of the West Indies, carrying all their storms in a N. W. direction; and what is true of them is true of the trade winds everywhere, all over the globe, over the land and over the sea.Doubtless here some one will say, our upper current is a S. W. current. True, the S. E. trade which enters the belt of rains and issues out on the north, a S. E. upper current or counter-trade, keeps that course until it arrives at the northern limit of the surface trade, when, in obedience to another law, which we shall notice, it gradually descends near the surface, curves to the eastward and becomes the S. W. current which passes over us. And so we have the S. E. trade-wind of the South Atlantic, with its moisture, warmth, electricity and polarity, over and perhaps sometimes around us, dropping the electric rain which makes glad our fields; giving us, when not prevented by other conditions, the balmy air of spring, the Indian summer of autumn and the mild mitigating changes of winter; and thus, our rivers, which run into the sea, return to us again.But let us go back to the trade-wind region; the region of regularity and uniformity; and examine somewhat more attentively its features, that we may more fully understand the character of this counter-trade.Here are 60° at least of the 180° of the earth’s surface and at its largest diameter, covered in the course of the year and of their travels, by the trade-winds at the surface, the counter-trades above and the belt of rains and comparative calms, formed by the action of the opposite trades, as they thread their way through each other, to assume the relation of counter-trades. Truly the magnitude, simplicity and regularity of this machinery are most wonderful.There are, however, some apparent anomalies which deserve attention. Here are most distinctly marked the rainy and dry seasons, existing side by side. Here are the rainless portions of the earth, already but briefly alluded to; here the monsoons and another peculiarity, viz.: the gathering of the counter-trades upon the western sides of the two great oceans, into two aerial currents of greater volume, analogous somewhat to the two gulf streams of those oceans. Let us examine these anomalies.The rainy and dry seasons depend, as we have seen, upon the transit north and south of the rainy belt, or belt of comparative calms. Wherever this belt may happen on any given day to be situated, each side of it the trades prevail, it is dry, the earth is parched and vegetation withers. These changes are graphically described by Humboldt in his “Views of Nature,” as they occur on the northern portions of South America, as follows: “When, beneath the vertical rays of the bright and cloudless sun of the tropics, the parched sward crumbles into dust, then the indurated soil cracks and bursts, as if rent asunder by some mighty earthquake. The hot and dusty earth forms a cloudy vail, which shrouds the heavens from view and increases the stifling oppression of the atmosphere; while the east wind (i. e. trade-wind), when it blows over the long heated soil, instead of cooling, adds to the burning glow.“Gradually, too, the pools of water, which had been protected from evaporation by the now seared foliage of the fan-palm, disappear. As in the icy north animals become torpid from cold, so here the crocodile and the boa-constrictor lie wrapped in unbroken sleep, deeply buried in the dried soil. everywhere the drought announces death, yet everywhere the thirsty wanderer is deluded by the phantom of a moving, undulating, watery surface, created by the deceptive play of the reflected rays of light (the mirage). A narrow stratum separates the ground from the distant palm-trees, which seem to hover aloft, owing to the contact of currents of air having different degrees of heat and therefore of density. Shrouded in dark clouds of dust and tortured by hunger and burning thirst, oxen and horses scour the plain, the one bellowing dismally, the other with outstretched necks snuffing the wind, in the endeavour to detect, by the moisture in the air, the vicinity of some pool of water not yet wholly evaporated.“Even if the burning heat of day be succeeded by the cool freshness of the night, here always of equal length, the wearied ox and horse enjoy no repose. Huge bats now attack the animals during sleep and vampire-like suck their blood; or, fastening on their backs, raise festering wounds, in which mosquitoes, hippobosces and a host of other stinging insects, burrow and nestle. Such is the miserable existence of these poor animals, when the heat of the sun has absorbed the waters from the surface of the earth.“When, after a long drought, the genial season of rain arrives, the scene suddenly changes. The deep azure of the hitherto cloudless sky assumes a lighter hue. Scarcely can the dark space in the constellation of the Southern Cross be distinguished at night. The mild phosphorescence of the Magellanic clouds fades away. Even the vertical stars of the constellations Aquila and Ophiuchus, shine with a flickering and less planetary light. Like some distant mountain, a single cloud is seen rising perpendicularly on the southern horizon. Misty vapours collect and gradually overspread the heavens, while distant thunder proclaims the approach of the vivifying rain. Scarcely is the surface of the earth moistened, before the teeming steppe becomes covered with Killingiæ, with the many-panicled Paspalum and a variety of grasses. Excited by the power of light, the herbaceous Mimosa unfolds its dormant, drooping leaves, hailing, as it were, the rising sun in chorus with the matin song of the birds and the opening flowers of aquatics. Horses and oxen, buoyant with life and enjoyment, roam over and crop the plains. The luxuriant grass hides the beautiful and spotted jaguar, who, lurking in safe concealment and carefully measuring the extent of the leap, darts, like the Asiatic tiger, with a cat-like bound on his passing prey.”Such is Humboldt’s description of the dry season on the Orinoco and the return of the belt of rains from the south.[Cat-like Jaguars, eh?I can't imagine why he isn't still widely read.(Wait until you find out how his superiors dealt with wild elephants when attacked.)]Again, within this trade-wind region are the rainless countries. These are portions of the earth which the equatorial rainy belt does not ascend far enough north in summer to cover, nor does the southern edge of the extra-tropical regular rains descend, in winter, far enough south to cover them and where, of course, rain seldom, if ever, falls. Such are the central parts of the Desert of Sahara, Egypt, Arabia, portions of Afghanistan, Baluchistan and the western parts of Hindustan, to the north of the inter-tropical belt and a similar state of things exists south of the equator in parts of South America, Africa and New Holland, although upon a comparatively small surface.Again, another anomaly is the gathering of the trade winds into greater volumes, on the westerly side of the great oceans and the consequent carrying of the equatorial rainy belt up to the region of extra-tropical rains, on the eastern side of the great continents of Asia and North America and the peculiar liability of these aerial gulfs to hurricanes and typhoons. Such an aerial gulf gathers over the Caribbean Sea and the West Indies. Passing across the Gulf of Mexico, it enters over Texas and Louisiana and the other southern states; its western edge passing north in autumn and winter, on the eastern side of the highlands of Western Texas, New Mexico and the Great Desert; curving, as all counter-trades do, to the eastward as soon as it passes the limit of the N. E. trades and spreading out over our favoured country, leaving the evidence of its pathway in the greater quantities of rain, which fall annually upon its surface. This gathering deprives a portion of the Atlantic, north of the tropics, of its share of the counter trade and there, as everywhere, where the volume of counter-trade is small, storms and gales are infrequent and of less force and comparative calms prevail. That portion of the Atlantic has long been known as “the horse latitudes,” a name given to it by our Yankee sailors, because, there, in former times, the old-fashioned, low-decked, flat-bottomed, horse-carrying craft of New England, bound for the West Indies, often floundered about in the calms and baffling winds, until their animals perished for want of water and were thrown overboard.[I find it difficult to believe that there were not enough Yankee businessmen in New England, astute enough to redesign their ship's architecture before the insurance companies put an end to the trade. Had they not the works of Hutton to guide them?Doesn't it make you weep that we left the Colonies to such amazingly stupid slave owners?]Lieutenant Maury, in his most praiseworthy and exceedingly useful investigation of “The Winds and Currents of the Ocean,” has defined the situation of these calms and baffling winds at different seasons; for they move up and down, of course, with the motion of the whole machinery; and enabled navigators to avoid them, by running east before they attempt to make southing; and very materially shortened the voyages to the equator.A like gathering, in volume, of the S. E. trade, on the western side of the Pacific, enters over Asia and covers China and Malaysia, extending, in its western course, nearly as far as the western edge of Hindustan. In this concentrated volume of counter-trade and owing to its concentrated action, form and float the typhoons of the China Sea and of the Bay of Bengal; and to this anomalous aerial gulf stream, the S. E. portions of Asia, from the western desert of Hindustan, to the eastern portion of China, north of the rainy belt, owe their great supply of moisture and fertility and their peculiar climate.[Let us hope the peculiarity didn't extend to the over liberal use of horses. Or did the Asian sailor learn too long ago for our historians to record it, that being lashed to death with the hooves of dead horses was not good business practice for regions where tropical storms was a likelihood?]The western line of this volume of counter-trade is marked by the eastern portion of the rainless region of Baluchistan and the north-western deserts of India, as the western edge of our concentrated volume of counter-trade, is marked by the arid plains of northern Mexico, western Texas and New Mexico. On the south of the equatorial rainy belt, there is no corresponding aerial gulf of equal volume, as there is no corresponding gulf stream of equal magnitude. On the western side of the Indian Ocean we find a gathering of the N. E. trades from the Bay of Bengal and the Indian Ocean, in which form and travel the hurricanes which prevail; travelling to the southward and westward; about the Isle of France or Mauritius; and the lagullus [Benguelan?] oceanic current, which runs down to the S. W. toward the Cape of Good Hope. But the extension of South America to the eastward, under, or just south of the N. E. trades, does not permit the formation of such a concentrated volume on the western side of the Atlantic, nor is the strength or regularity of the N. E. trades, on that ocean, equal to those of the S. E.Nor is the magnetic intensity on the eastern and middle portions of the Pacific, sufficient to produce such a concentration, in large volume, there. The trades over that ocean, therefore, curve without concentration, except a partial one, over the western groups of Polynesia, which the Asiatic line of magnetic intensity approaches and where hurricanes are sometimes found, until we arrive near the eastern line of magnetic intensity, on the eastern side of Asia. We shall, hereafter, have occasion to follow the anomalous concentrated volumes of the S. E. counter-trade, of the northern tropic, on the western side of the great oceans, in explanation of some of the phenomena which we find north of the trade-wind region. Suffice it here to add, that if it were not for the concentration of these counter-trades, on the western side of the great oceans, the rainless region between the parallels of 20° and 30° would encircle the earth; and China and the Eastern United States would have a distinctly marked rainy and dry season, as have California, the Barbary States, Syria, Persia and other countries which lie north of the rainless region, within the summer range of the N. E. trades but also within the winter descending range of the belt of extra-tropical rains.Another anomaly which we find in the trade-wind region, is the monsoon. There are several of them but they are found, in the greatest strength and regularity, in the Indian Ocean. Another, defined by the investigations of Maury, is found on the west coast of Africa, extending out over the Atlantic. Another prevails on the western coast of South and Central America. The etesian winds of the Mediterranean are but the N. E. trades, whose northern limit is carried up in summer, by the transit of the connected machinery, to the north, over that sea. The N. E. and S. E. monsoons, so called, of the Indian Ocean, are but the regular trades, blowing when the belt of rains is absent, as they do all over the globe. The N. W. monsoon, south of the equator, in the vicinity of New Holland; the S. W. monsoon which blows from the Arabian Sea, in upon Hindustan; the S. W. monsoon of the Atlantic, south of the Cape De Verde Islands; and the variable west monsoon winds of the west coast of Southern and Central America and Southern Mexico (known under several different names but chiefly by that of Tapayaguas), are all that deserve attention as such.At first sight they appear to be anomalies but the facts declare their character with perfect certainty. First, they are not continuous, like the trades but prevailing winds and are storm winds; they always blow toward a region, or portion of the ocean, covered at the time by clouds and falling weather.Second, they do not blow upon, or toward, heated surfaces of land or water; i. e., toward the dry and parched surfaces, where the dry season prevails, or from adjoining cold waters on to warm surfaces but toward the land or water situated under the rainy belt. They are therefore incident storm winds, (as our easterly winds are incident storm winds) of the rain clouds of the tropics. They blow in upon the land, under the belt of rains, while that belt with its daily cloud and inducing electric action, is over it and follow that belt in its transit north and south. They blow from the warm south polar current of the Atlantic, which flows N. W. from the coast of Africa, toward the inshore north polar current, which is there flowing south but under the belt of rains. In the Indian Ocean they blow from the centre of that ocean and the Arabian Sea, toward the belt which hangs over Hindustan, from the S. W.; and when the rainy belt travels south they still blow toward and under it, from the Indian Ocean but of course from the N. W. The heated character of the waters of the Indian Ocean and Arabian Sea, which receive no polar currents but heated waters from the Persian Gulf and from rivers which flow into the Bay of Bengal over the heated plains of a tropical country, explain this. So, too, the monsoon of the Atlantic Ocean, does not blow north of the Cape De Verde Islands, where the heated surface of Sahara, burning with the rays of a vertical sun, has a temperature sometimes ranging from one hundred and forty to one hundred and sixty degrees; but remains under the rainy belt, drawn from the heated waters which flow up from the South Atlantic and travels north as the rainy belt travels north in summer and south to the Gulf of Guinea, as that travels south in winter. The same is true of the Pacific monsoon, the Tapayaguas, the least marked of all, which blows in during the rainy season upon the west coast of Southern Mexico and of Southern and Central America. They are all incident rain or storm winds, blowing in upon the land, or on to a colder surface of different polarity, during the rainy season; and if it were possible to catch one of our north-easters, in its passage over our country to the eastward and anchor it to the Alleghenies, “paying out” so to have it reach in part over the Atlantic and keep it there in operation six months, we should have a continual easterly wind under it; a monsoon more strongly marked than the monsoons of the Indian, or Atlantic Oceans. The received theory in relation to them is a fallacy.Recapitulating, then, all the phenomena, we have; Surface-trades, blowing toward the centre, passing through each other and continuing on as upper or counter-trades; a belt of rains, with calms near the centre, formed by the trades where they meet and pass through each other, which travels with them north and south following the sun; two belts of drought, following the belt of rains and the trades and followed by the extra-tropical line of rains, as it travels with the trades and the rainy belt, leaving a part of the earth which the equatorial rainy belt does not travel far enough north, nor the extra-tropical line of rains far enough south to cover and which is consequently a rainless region; the monsoons, which are but incidents of the rainy belt and the gathered volumes of counter-trade, on the west of the two great oceans, which usurp the place of the N. E. trades, carrying the rainy belt up to the region of extra-tropical rain and preventing the rainless region from encircling the earth.Upon what cause do these great central phenomena, so vast, so regular, so wonderful, depend?What is the motive power of this connected atmospheric machinery, whose action and influence extend over the entire globe?“Heat, heat,” say the text books, the Professors, the votaries of meteorology. “All these phenomena are owing to the heat of the sun. It heats the ocean and the earth; the air is thereby heated and rises, the cold air rushes in from below, then the ascended current rolls off each way at the top toward the pole, acquiring a westerly motion from the rotation of the earth, slipping away from under it and a different, viz.: an easterly motion, after reaching the latitude of 30°, from the same rotation; and all the winds and disturbances of the atmosphere are produced in the same way. They are produced by the action of heated surfaces upon the adjacent atmosphere.”This is the great theory of meteorologists, by which they attempt to account for the various atmospheric disturbances, of both tropical and extra-tropical regions.The whole theory is a fallacy; it will not stand the test of a careful examination. The bases of the theory, which are assumed to be facts, are not so. The agent has not the power claimed for it. A heated surface, alone, never caused any considerable ascending current, or if it did, never produced a mile of wind. I repeat it, the theory and all incidental ones; the thousand explanatory and modifying theories and hypotheses; the whole system; is without foundation in fact and will not bear a critical examination.Let us see if this language is stronger than the facts will warrant.The theory assumes that both the land and water, under this central belt, where the air is supposed to be rising are materially hotter than the land and ocean are on either side of it. Now, how much hotter are the air and the land under the belt of rains and calms, upon Hindustan, or Africa, or South America, where the former is supposed to be acquiring heat and expansion so rapidly and to be ascending, than under and in the dry belts on either side?None; it is cooler by the thermometer; much cooler.The central belt of rains in midsummer over Africa, extends up as far as 17° north latitude and perhaps further. North of this line over the whole surface of the desert, the Barbary States, a part of the Mediterranean and some portion of Italy, the dry season extends and from the entire surface the N. E. trade blow into the central belt.[1] Over the desert they all pass. Now this desert is a sea of sand, under a vertical sun, intensely heated, blistering the skin with which it comes in contact and often acquiring a temperature of 150° to 160° of Fahrenheit.[By day, yes. At night it is rather cool in deserts.]Under the central belt of rains neither the earth nor air exceed the temperature of 84°. And yet the hot air of the desert does not ascend but blows into this cooler central belt; and when it is felt as it blows off the western coast by the mariner, or even in Guinea, when the belt of rains has gone south in winter, as it often is as the harmattan, it is suffocating and intolerable. There, then, not only is it untrue, that the land and the air over it under the rainy belt are hotter but it is true that intensely heated air blows horizontally from the Desert of Sahara.[Modern research has it that African and Arabian dust storms reach South America, not just the shores but the sand can be found in the ice cores taken from glaciers in the Andes]Nay, as it will appear in the sequel, this hottest of all surfaces not only can not have a vortex but it can not induce a monsoon and scarcely a sea breeze. The same is true in a great degree of the surface and the air over it, on either side of the supposed vortex of the rainy belt upon South America. See the description of Humboldt, already given, where the thermometer stood as high as 115° of Fahrenheit in the shade, while the N. E. winds, the regular trades, were blowing over the land. And it is equally true of Arabia and indeed of every portion of the earth. There is not a spot upon the globe where the land and the air are cooler by the side of the central belt of rains, than under it. And the opposite is true everywhere upon the land.How much hotter is the ocean and air under this supposed vortex?But little hotter than they are on the side where the sun is not vertical and none on the other. Let us be a little more particular. The temperature of the Atlantic under the belt of rains in our winter and on the south of the belt at the latitude of 3° south and down to 9° or more south, is 82°. The air may range a degree, or possibly two, higher than the water at either point. On the north this difference is from nothing at the meeting of the trades and belt of rains, to about 4° at their northern limit. This is too trifling to be worth one moment’s consideration. It is less, far less than the difference between the water and air of the Gulf Stream which runs along our coast and the adjoining waters and air over them. While on the south side of the belt of rains the difference is actually against the theory; and the same state of things is reversed in summer, when the sun is vertical at the north.From the log of an intelligent ship-master, found in the wind and current charts of Lieutenant Maury, I abridge the following, which will illustrate this. Captain Young in February, found the N. E. trades at about 17° north latitude, with the water at 75° and air at 76°, trade-wind N. E. At 12° 16′ the water was 75° the air 76° wind N. E.Feb. 22nd. 9° 49′ " 76½° " 77° " N. E." 23d. 7° 13′ " 78° " 78° " N. E." 24th. no obs. " 79½° " 79° " N. E., E. S. E. rain." 25th. 3° 10′ " 81° " 83° " E. S. E. rain." 26th. no obs. " 82° " 82° " S. E. to E. S. E. hazy, rain & sqs." 27th. 2° 24′ " 82° " 82° " calm, with rain." 28th. no obs. " 82° " 82° " calm rain.March 1st. 0° 29′ " 82° " 82° " E. S. E. sqs. rain." 2nd. 1° 27′ S. L. " 82° " 82° " S. E. sqs. rain." 3d. 2° 44′ " 82° " 83° " S. E. & S. S. E. weather settled." 4th. 4° 17′ " 82° " 83° " S. S. E. & S. E. fair weather." 5th. 6° 08′ " 82° " 84° " S. E. fair wthr." 6th. 8° 08′ " 82° " 84° " S. E. & E. S. E. fair weather.Here the air was seven degrees colder at the extreme limit of the N. E. trades than in the centre of the belt of rains, as it is, usually, in mid-winter but not in summer. On the other hand, after he left the region of calms and rains, where the water and air stood with almost entire uniformity at 82°, on the 3d of March and for three days thereafter, during which he was in the S. E. trades with fair weather, the water was the same as under the supposed vortex, viz., 82° and the air rose to 83° and 84°! This is demonstration.I also take from a letter of Lieutenant Walsh to Lieutenant Maury, relative to the cruise of the “Taney” the following, showing the warmth of the Gulf Stream compared with the adjacent ocean.“We first crossed the Gulf Stream on the 31st of October; we struck it in latitude 37° 22′, longitude 71° 26′ as indicated by the temperature of the water, which was as follows:8 A.M. water at surface 66°9 " " " 73°10 " " " 76°11 " " " 77°77° was the highest temperature found in crossing at this time.Re-crossing it in May, in latitude 35° 30′, longitude 72° 35′, he found the water as follows:8 A.M. water at surface 71° 8′9 " " " 73°10 " " " 75° 5′11 " " " 78° 5′12 M. " " 78° 5′79° being the highest temperature found.”The average difference between the temperature of the water of the Gulf Stream and the adjoining ocean, at the line of division, is about ten degrees, increasing to more than twenty on approaching the coast and within one hundred miles; a far greater difference than is ever found on the winter side of the inter-tropical rainy belt.It is not only not so, then, that the surface of the ocean is materially warmer under the belt of rains than the adjoining surface under the trades, especially on the summer side but if it were so, the trades would not be created thereby, any more than upon the Gulf Stream. And the opposite is true of the land where the line of calms and rains and drought meet, all around the globe. The fact assumed is therefore untrue. The hottest surfaces, even at the rainless portion, where there is no vortex, no storm and no wind but the continual uniform N. E. horizontal trade-wind, never created, by reason of the heat alone, a mile of wind, a storm or shower.But, again, the belt of calms, where the air is supposed to rise and create a suction which draws the trades on either side a distance of from one thousand to two thousand miles, an average of three thousand miles in all, at least, is not itself, on an average, over five hundred miles in breadth from north to south. What a wonder of meteorology is here![The secret of course, is in the upper atmosphere in the clouds he has so quickly passed in daguerrotype.The upper troposphere may be heated by cooling. The ice formed in that region falls out as a layer of cloud thin enough to allow light to penetrate and to be converted down in wavelength. This light can no longer return through the same cloud having either become impermeable to that radiation or said radiation having moved on to accomplish heating to be absorbed by vegetation.The band of cloud so formed is some several hundred miles wide.]With a breadth of five hundred miles, the rising of the atmosphere is supposed to be so rapid and of such immense volume that it draws the surface atmosphere, one thousand to fifteen hundred miles on one side and two thousand on the other, with a uniform steady velocity of twenty miles per hour. Is this vast suction found by the unlucky mariner who may be drawn within the vortex?Not at all. He finds no rapid suction there but horizontal currents, not steady, indeed, like the trades and sometimes calms at the centre but still the currents are there, and, except near the centre, there as squalls, showers and baffling winds and as monsoons.Again, is there at the mouth of this vortex, or as you approach it, an increased rapidity in the trade corresponding to the magnitude of its influence?Does the trade become a hurricane as it approaches the spot where it is to supply the place of that which has suddenly “expanded by heat and been forced to rise, boil over and run off at the top in turn?” Not at all. It blows gently, even up to the very line of the rainy belt and becomes squally and baffling, falls gradually calm near the centre, or changes to a monsoon.But, again, the belt of rains is so far from being a belt of calms strictly, that its monsoons in the Indian, Atlantic and Pacific Oceans, at times, extend hundreds of miles out over the ocean. That of the Atlantic, triangular, with its base resting on Africa, according to Lieutenant Maury, extends sometimes almost to the coast of South America, a distance of one thousand miles and thus under the supposed ascending vortex. Where is the great uprising suction during the prevalence of this extensive surface horizontal monsoon beneath it?Manifestly it does not exist. Nay, that monsoon is blowing from the warm current which sets up from the Cape of Good Hope toward the Caribbean Sea and over the cold north polar current, which runs down between the continent and the Cape de Verdes. Equally untrue is the presumption that the air rises over heated portions of the earth elsewhere and by reason of such heating. Perpendicular currents of the atmosphere are rarely seen, never extensive, or attaining any considerable altitude. I have watched for them thirty years. I have seen currents of air ascend, with their moisture condensing as they ascended and unite with the under surface of a highly electrified cloud; the advance condensation of a thunder shower; but that cloud was moving horizontally at a distance of from one to two thousand feet above the surface of the earth and did not rise. I have seen patches of scud rising from the surface during the intervals of a showery and highly electrified storm, toward and uniting with, the clouds above, when very low, as I have seen them approach and unite horizontally; and doubtless there is a tendency upwards of the wind, created and attracted by the summer shower, as may be seen in the ascending dust before the rain but I have never been able to detect an ascending current, except as induced and attracted by a cloud above moving horizontally, in the hottest day or driest time.None of the clouds of our climate, even when the earth is heated and parched by a two months’ unbroken drought, can be detected rising above the strata in which they form. I have watched the cumuli at such periods when they filled the air and can assert that they never rise. The atmosphere moves, invariably, in horizontal strata and the whole theory of ascending currents is fallacious.But let us look still further at the tropical currents. The true harmattan of north-western Africa (for the term is sometimes misapplied), hot and blistering, generated upon the sand of the desert; why does it blow from Sahara horizontally, on or over cooler surfaces, following the belt of rains as a N. E. trade?Why does it not ascend?The sirocco of north Sahara, the kamsin or chamsin of eastern Sahara and the simoon of Arabia, which blow hot and suffocating from those deserts; why do they blow from heated surfaces and horizontally over cooler ones?Why do they not ascend?Arabia is surrounded on three sides by seas and gulfs, from which evaporation is rapid. Her interior deserts are extensive and intensely hot; why are they rainless?Why do they not have a vortex, a monsoon, or even a shower?Because there is no such law or action as this theory supposes. Those winds blow horizontally in obedience to other laws and under the control of other and more powerful agents. But further still, what heating and ascending process is it that makes the variable winds north of the tropics?that brings in the warm air and fog of the Gulf Stream upon our snow-clad coast, in mid-winter, to increase the January thaw?Nay, what heating process is it that disturbs the calms of the polar regions with fresh breezes and gales, sometimes of the force of 6, when the sun does not shine, the thermometer is from 20° to 40° below zero, the earth and sea one frozen surface and the hardy explorer dressed in furs, barely lives in his cabin covered by an embankment of snow and heated by a stove?Gentlemen, meteorologists, it will not do. The theory is unsound; the assumed facts do not exist. The whole universe has not an agent, organic or inorganic, which can play such absurd and inconsistent pranks in the face of its Creator, as your various and complicated theories assign to caloric.Away with the theory and all its incidental and complicated and mystified hypotheses, they rest like a pall upon the science; away with the whole system and let us seek some agent whose power and adaptation correspond with the extent and simplicity and magnificence of the phenomena, and, in some degree, with the power and wisdom of their Author.CHAPTER V.One (and the principal) end attained by the power of the agent, is the gathering of a volume of atmosphere from, or near, the surface of the land and sea, so as to ensure its possession of all the moisture of evaporation which rises from the locality and the highest degree of temperature and from a space ranging from one to two thousand miles in width, in one hemisphere and to carry it over into the other. Not over the top, or upon the top, of the whole mass of atmosphere situated in the opposite hemisphere; out of reach of all influences from the earth; but through it and curving gradually down near to and within influential distance of the surface of the earth, soon after it passes the outward limit of its fellow trade; and to continue the current onward, leaving portions of it and its heat and moisture on the way but taking a considerable volume up and around the magnetic poles; it being impossible for the entire volume to be thus carried around the poles in consequence of the diminished circumference of the earth. To this end it is obvious it must possess polarity.[Daft as it sounds, it is hard to argue with that when you look at the compressive action of cyclones at the South Pole and wonder where “it” all went and just how they might be related to earthquakes (which they are admirable forecasters of.)]Another end to be attained is to combine the moisture of evaporation with the air, so that the cold atmosphere through which, or the earth over which it passes, may not be continually condensing its moisture and thereby enveloping the earth in a perpetual mist; but so that it may part with it at intervals, making cloudy and clear days; and part with it in portions, so that a regular and necessary supply may be furnished to the entire hemisphere, even up to the geographical poles. Is there such an agent?There is, precisely and perfectly adapted to the ends to be attained, ever there and ever active and that agent is magnetism.[Oh dear. Oh dear. Oh dear. Oh dear.Actually he may be right. I'm thinking about the outer atmosphere where it is affected by the solar wind. But it is difficult to see how that would work.]The earth is a magnet. It has its magnetic poles and they are distinct from its geographical ones; and there are two in each hemisphere. They are situated from 17° to 19° distant from the geographical poles; and ours is not far from longitude 97° W. from Greenwich and 71° north latitude. Navigators have gone north and north-west of it and found its situation by the declination of the needle. From these poles, lines of magnetic intensity extend to the opposite and corresponding pole of the other hemisphere and upon or near those lines the needle points north without variation; and toward these lines of no variation the needle everywhere, on either side declines. The foregoing diagram shows the situation of our magnetic pole and line of no variation, the dip of the needle by the arrows and the magnetic equator.[It is interesting that geophysicists, in their wisdom, prefer to believe that the magnetism in in the earth rather than the skies.Yes you can take buckets of earth and not find a use for it s magnets even if taken from directly below the magnetic north.That is the problem, their taking it from BELOW.Hmmmm!Maybe I am a convert?]Recent discoveries have shown that the magnetic force is exerted in lines and currents; that such currents, as physical lines of force, surround magnets and currents of electricity. Doubtless such lines of force exist around the earth and the magnetic poles. There are also longitudinal lines of force existing and active, between the poles and extending from one side of the centre to the other, occupying nearly one third of the magnet. If you take a large needle thoroughly magnetized, place it upon paper and drop filings of iron upon it, they will become arranged about it in circular and perpendicular and also in longitudinal lines, conforming to the currents. This experiment is illustrated in all our books on natural philosophy.The foregoing diagram, copied from Olmstead’s Philosophy, does not show as accurately as Faraday’s projection of the lines upon a globe-magnet the comparative distance from the poles of the needle, at which the longitudinal currents commence and terminate and where the filings will not adhere to any considerable extent. The lines shown upon the needle should bear the same proportion to its length as the trade-winds bear to that of the earth, measured from pole to pole and if the needle had a globular form they would so appear.These lines are made by currents arising from one side of the magnetic equator and passing over to the other. Doubtless, just such currents rise and pass over upon the earth.[Magnetic equators?But at the magnetic equator the like and unlike are of equal strength. Also, the earth harbours too much heat below the soil, jacketing metals in their molten form (only some of which are magnetic when cold and none of which are magnetic when red hot) and shielding us on the surface from both heat and magnetism. (Not that I subscribe to that theory either. It seems a little too unbelievable and I prefer to wait until we have sent someone down there, able to roam about freely, with a reliable thermometer.)]Magnetic and electric currents carry the air with them. This is well settled by experiment. Oxygen, too, is magnetic and capable both of receiving and retaining polarity and of combining with, or attracting and retaining vapour and of course the moisture of evaporation. Here then we have a power existing, capable of producing the result; precisely and with evident wisdom adapted to its production; ever present and active; and no other known agent can.Is it not then the agent?[Aja doan theen soooo.]Let us look a little further.[aja carramba, aja theen this toooo.]This result is affected by the action of the sun: the trades with the central belts of rains travel north and south after it; so does the sun affect the magnetic currents everywhere, even the magnetic needle is daily affected by its action, as it increases the intensity of the terrestrial magnetic currents and hence its well established diurnal oscillations.[Aja caramba!]Again, along the eastern lines of the continents which skirt the great oceans on the west, run the northerly and southerly lines of no variation and of greatest magnetic intensity. Here are the trade currents gathered into a volume, which curve and carry unusual fertility to South-eastern Asia and North America and in those great aerial gulf streams we find the intense electric action which produces the typhoons of the former and the hurricanes of the latter.It may still be said that these conditions and phenomena of the trade-wind region, are not produced by magnetism or magneto-electricity but the objector can point to no other adequate power. That it must be heat, electricity, or magnetism, must be admitted. There is no other power known. Heat demonstrably can not produce them. Magnetism or electricity therefore must and they are doubtless states or phases of the same power, producing in their different states or phases the different results. And even heat; atmospheric temperature, is often, if not always the result of their action. In the present state of science, it is enough for me that the magnetic longitudinal currents are there; that they are lines of force and adequate; that oxygen is magnetic and therefore the atmosphere must be affected by them; that so far as we can reason from analogy, they ought to produce the effect upon the atmosphere which we find produced and until further light is thrown upon the subject I shall presume that they do. Every step we take hereafter in this investigation will confirm the presumption.There is one peculiarity to be more particularly noticed before we leave the trade-wind region and we are now prepared to notice it.The belt of rains, formed by the currents of the two trades, threading their way through each other; how are they produced?Why should the place where the currents thus pass through each other be a place of almost daily precipitation?There is, in fact, no ascension, except that which the currents have in their line of ascent to attain the elevation which the magnetic law of the current requires.The trades have passed over an evaporating surface and are charged with moisture. This moisture they hold in magneto-electric combination. evaporation does not depend upon temperature. Ice and snow evaporate at all temperatures (Howard, vol. 1, p. 86). So the cold N. W. wind, full of positive electricity, will lap up, as it were, the pools from the earth, with astonishing quickness; and when this electricity is deranging the action of the machinery and material of the manufacturer, he allays it by a supply of moisture, with which the electricity can combine. Nor does the air lose its moisture when below the freezing point. In all parts of the atmosphere, as at the surface of the earth in winter, moisture is held in large quantities in the coldest and severest weather; and it is not till it moderates and a perceptible electric change takes place, that it is precipitated as rain or snow. Doubtless there is an exposure of considerable surfaces, of opposite currents, charged with opposite polarity and a constant depolarization where their surfaces meet. May there not be a consequent dissolution of the electro-magnetic combination between the air and moisture, or the excitation of that electric action which attends or produces like rains everywhere and hence the constant precipitation?This is rendered probable, by the fact that precipitation, at the meeting of the trades, takes place in level countries in the day-time, between 10 A. M. and sunset, in showers, with thunder and lightning, as with us in summer, although among the mountains the rain sometimes falls in the night also. The precipitation in the heat of the day is obviously induced by the action of the sun, although it is by no means certain that the friction of the opposing surfaces does not assist in the operation.I am well aware that the lines of magnetic force curve upward and carry the trades with them and that, therefore, precipitation by condensation from the mere cold of the upper stratum of the atmosphere is possible. But, there are three reasons why I do not believe such to be the fact.1st. Precipitation takes place in the day time mainly and in sudden, isolated, heavy showers and not in steady continuous rain. Nor is there condensation or continual mist at other hours of the day.2d. They occur at a time of day when the sun is affecting the magnetic currents most powerfully, viz., between ten o’clock A. M. and sunset and mainly at the time of greatest heat.3d. The counter-trades do not precipitate after they leave the rainy belt, although at a great elevation, until they reach the outward limits of the trades; and they do precipitate again, although they gradually descend nearer the earth, as soon as they become subject to the action of the currents of an opposite magnetism. Their precipitation is partial too, even then and they carry a portion of their moisture through an atmosphere of the coldest temperature up to the geographical poles.A similar result attends the action of the sun in the extra-tropical regions. Cumuli commence forming in the counter-trade, or at the line between that and the surface current, at the same time of day that the diurnal motion of the magnetic needle commences, or the rain clouds form in the tropics; they continue to enlarge here as there, till about the same hour of the day that the needle obtains its maximum diurnal variations; and when the influence of the sun upon the needle ceases and it returns to its original status, the cumuli disappear. Hail storms too, it is said, always, or generally occur in the day time.In like manner the sea-breezes and other fair-weather surface winds, rise in the forenoon with the influence of the sun upon the magnetic currents and the needle and die away at nightfall when the influence ceases.There are other electro-magnetic, or to speak more correctly, magneto-electric, effects of the sun’s action equally illustrative, which tend to show that the precipitation at the passing of the trades, is the result of their action upon each other, aided by the sun, to which we shall allude when we come to speak of the causes and character of the surface winds of the extra-tropical regions.As, however, this takes place only, or mainly, where the threading surfaces meet, it is but partial and the body of the respective polarized currents pursue their way unaffected, toward the opposite magnetic pole; and there for the present we leave them.Storms sometimes originate in these currents, when concentrated, as in the West Indies, the China Sea, the Bay of Bengal and Indian Ocean, while passing through the rainy belt and move with the current to the north-west if issuing on the north side of it and to the south-west if issuing on the south side of it, until they respectively get beyond the extreme limits of the trades and then they curve to the eastward, embedded in and following their current. The peculiar extension of the land to the east on the northern portions of South America, prevents the gathering of an aerial gulf similar to the one which we have described to the north-west, entering upon our division of the continent over the Gulf of Mexico. It is otherwise in the Indian Ocean and there the storms are found issuing from the rainy belt on the southern side, sweeping over the Mauritius and other islands of that ocean and often simultaneously with storms issuing on the north over the Bay of Bengal. Colonel Reid mentions instances and gives a diagram.[2]These storms, in milder forms, issue from the rain belt at other points and may issue any where but will always be found most extensive and most violent, that is to say, as hurricanes and typhoons, in the concentrated volumes of counter-trade on the western side of the great oceans, within a few hundred miles of the lines of magnetic intensity and no variation and when they form in the rainy belt they are highly electric. Most frequently, however, as we shall see, they form in these currents after they have issued from the rainy belt and after they have passed the extreme limits of the trades and become subject to the circular and perpendicular magnetic currents which exist north and south of the longitudinal ones and which when seen upon the magnetic needle, attract the filings and cause them to adhere; although but slight attraction or adhesion takes place where the longitudinal currents exist.Such, then, are the atmospheric arrangements and phenomena of the trade-wind region and the cause that produces them; such is the character and cause of the enlarged volume of counter-trade, which spreads out and blows over our country as permanently as the S. E. trades blow on the South Atlantic and South America, returning to us the rivers which had run from us to the sea.[The magnet theory falls at the first enquiry made by anyone of any other persusion:Why do the major magnetic poles remain where they do? Any movement of one air current about another if not immediately grounded, would force a transduction from motion to magnetism. Also that transformation of energy would be dangerous to man and beast, would be set up all over the earth and of no limitless duration making it impossible to navigate.Radio frequencies would be permanently interfered with by unmitigated currents of atmospherics.It is obvious in this day and age that this is not capable of happening and indeed it has been shown that sandstorms once considered electrical as well as thunderstorms and other forms of such phenomenon once considered able to build up electrical fields, do not do so.]
Start again:CHAPTER VI.Coming back now, to a consideration of the course and functions of the counter-trade after it leaves the northern limit of the surface-trades, we find it curves to the eastward and gradually assumes about an E. N. E. course and becomes a W. S. W. current where it crosses the line of no variation and continues on until it passes off over the Atlantic; and this course and curve is analogous to what may be found true of the counter-trades everywhere. It is best illustrated by the course of all the storms (in the American sense of the word, as distinguished from thunder showers and other brief rains), which have been traced north or south of the limits of the trades. It was found by Mr. Redfield in most of the storms investigated by him, which originated within, or north of the tropics.Doubtless it was the actual course of the others and that the investigation was imperfect. All the great autumnal, winter, or spring storms which have traversed the whole or any considerable portion of the territory of the United States, east of New Mexico, which have been investigated by Professors Espy, Loomis, Redfield, or others, have been found to follow this course. A storm which passed over Madeira, appears from the investigations of Colonel Reid to have followed the same law of curvature.And so, doubtless, did another which he has described as passing over the Levant. The storms which supply the winter rains of California and Utah, reach them by this law of curvature and progress, after the northern limits of the trades have descended to the south with the sun, so that the counter-trades of the Pacific may descend to the surface and curve in upon them. But the absence of a concentration of the counter-trade and its deficient action because of its passage over mountain ranges and their location so near the northern limit of the trades that their storms can not expand and become extensive, as well as their weaker magnetic intensity, prevent their storms from becoming violent and their supply of rain is not large and much of it falls in showers. The same is true of the Barbary States, of Syria and Persia and of Southern Europe; and indeed of all the countries of the globe which lie between the winter and summer extreme limits of the surface-trades and without the limits of the two concentrated counter-trades. Enough appears in the writings of the meteorologists of Europe to show, that their long continued rains, which are analogous to our storms and are preceded by the formation of the true cirrus of the counter-trade, follow the same great law of curvature and progress; although the presence of the Gulf Stream with its mass of south polar waters on the western side of the British Islands, Denmark and Norway supplies them with showers, and fogs and cumuli from the west and north-west and makes the mean of the surface winds of their storms somewhat variant from ours. A like law -reversed, prevails in the southern hemisphere. The storms of New Holland and the Indian Ocean, south of the limits of the trade, curve to the eastward and travel about south-east, their south-west being a clearing off wind as our north-west is and precisely similar in all its other characteristics, where the relation of magnetic intensity is the same.The storms of the Pacific on the S. W. coast of South America, in like manner travel to the S. E., flooding the western slopes of the mountain ranges with rain and aggravated by the intensity of the magnetic currents at the extremity of the continent in a high latitude, meet the mariner in the face as he emerges from under the lee of the land and attempts to pass the Horn. It will ultimately be shown that the precipitation which takes place, as the storms and counter-trades pass north and east in the northern hemisphere and south and east in the southern hemisphere, is owing less to cold than increased magnetic intensity. And all this is the result of one great uniform law, existing everywhere, varying in its phenomena only in consequence of the difference in volume and magneto-electric intensity of the portions of the counter-trade, as of the surface-trade at different places and the different magnetic intensity of the local perpendicular and circular currents of the earth over which they pass, at different periods and at different points.Mr. Redfield and Lieutenant Maury have assumed that our S. W. current comes from the Pacific Ocean. Aside from the adverse evidence which the investigations of the former in relation to the course of the West Indian storms and their curving over the continent, furnish to the contrary and that which has herein before been stated in relation to the law of curvature, it is obvious they are mistaken, for another and conclusive reason.In order to reach us from the Pacific in a direction from S. W. to N. E., it must pass the table lands and mountain ranges of Mexico and New Mexico and it would supply them bountifully, even if it did not thereby leave us comparatively rainless and sterile. Everywhere currents passing from the ocean over mountain ranges part with a large share of their moisture. Thus the counter-trade which curves over the Andes and over Peru, is deprived of its moisture and leaves the western coast rainless. So in degree of the counter-trade which curves over the Himalaya and Kuenlon Mountains and from there passes over the Desert of Cobi, to the north and east; it is deprived by those elevated ranges of its moisture. So the mountains on the south-western coast of South America are drenched with rain, while Patagonia, which lies on the east of them is comparatively dry. And so of every other country similarly situated.Now the mountain ranges and table lands of Mexico are not thus supplied with moisture. For the space of four months in Southern and less in Northern Mexico and in summer and while the belt of the tropics is extended up over them, they have rain and in daily showers which travel up from the south, indicating the course of the counter-trade. (See Bartlett’s Personal Narrative, vol. ii. p. 286.) At other seasons and while we are bountifully supplied, they are dry. In short, there are no two portions of the earth that differ more widely in regard to their supply of moisture and all their climatic characteristics and relations. It is therefore, according to all analogy, impossible that our counter-trade should come from the South Pacific across the continent and below 35° and in this also those gentlemen are mistaken.Messrs. Espy and Redfield recognizing the existence of “a prevailing” S. W. current but considering the surface-winds beneath it as the principal actors in producing the atmospheric conditions and changes, have attributed no office to that current, except that of giving direction and progression to our storms. This is their great mistake. It plays no such unimportant part in the philosophy of the weather, as we have already incidentally seen and will proceed still further to consider.All our storms originate in it. This we may know from analogy.Where there is no counter-trade, outside of the equatorial belt of rains and within influential distance of the earth, there are neither storms nor rain. So, when, as we have seen, the concentration of the volume of northern counter-trade in the West Indies, gathered by the hauling of the S. E. trades more from the east, as they approach the central belt, diminishing the volume of the counter-trade over the North Atlantic, the calms and drought of the horse-latitudes are found. And when the counter-trade is small in volume and weak in intensity, by reason of the fact that the surface-trades from the opposite hemisphere which constitute it, formed upon land where evaporation was small, as upon Southern Africa and New Holland, or formed where the magnetic intensity was weak, or passed over mountain ranges in their course, the annual supply of rain, the ranges of the barometer and the alternations of atmospheres conditions are remarkably less.We have already seen where the rainless portions of the earth are and why they are so; because those lying north of the northern limit of the equatorial rainy belt were yet too far south to be covered by the line of extra-tropical rains; or in other words, too far south to be uncovered by the surface N. E. trades and the longitudinal magnetic currents and to be covered by the counter-trades in contact, or nearly so with the earth and influenced by the perpendicular north polar magnetic currents. Thus we have seen that the rains of Southern Mexico were summer rains, due to the northern extension of the equatorial rainy belt; those of California were winter rains, due to the southern extension of the extra-tropical rains following the N. E. surface trades. We have also briefly alluded to the fact that either side of the equatorial rainy belt, evaporation is going on for months under a vertical sun, without precipitation; unless it be from an occasional brief storm of great intensity which originates in that belt at the line of it and passing on in the counter-trade, reverses, for the time being, by its concentrated and powerful action, like a magnetic body introduced into the field of another magnet, the surface-trades. Mere evaporation then, does not produce the storm, or shower, or rain, where most active in the dry torrid zone. It may be said that those dry portions are, for the time being (as the rainless portions of the earth are continually), within the operation of the surface-trades and that therefore the evaporated moisture is carried away by them toward the equatorial rainy belt. Precisely so; but why carried away?Why should it not condense, occasionally, at least and drop the rain as it passes along, if a great supply of moisture from excessive evaporation could furnish rain. Perhaps it may still be said it is going from a cold to a warm section. This is not true, as we have shown.But, it may be said that the rainless regions at any rate receive no moisture and therefore can not supply any by evaporation. This would not meet the case, as it would still be true that when the rainy belt has left a given spot, the dry weather sets in with excessive evaporation and the north-east trades in summer, blowing from the countries lying north of the rainless regions and which have been supplied during the interval by the extra-tropical rains and are loaded with evaporation, are passing over the rainless regions on their way to enter the central belt. So blow the N. E. trades from the Mediterranean and the Barbary States over the Desert of Sahara and into the rainy belt south of it; but drop no moisture on their way, because exposed to no magnetic currents of an opposite polarity.But it is not true that all the rainless regions are without evaporation. Egypt is an exception. The annual freshets of the Nile saturate its central valley and vast reservoirs of water are saved from it and let out over its surface and it all evaporates but produces no rain. And so are large quantities turned aside and scattered over the bottom lands of Northern Mexico and other countries, during the dry season and their evaporation furnishes no rain. Hygrometers and dew points are of no consequence there; nor are they of any, on either side of the rainy belt, where six perpendicular feet of moisture is evaporated in six months.Again we have alluded to a strip of coast on the Pacific west of the mountain ranges of South America, lying partly in Peru, partly in Bolivia and partly in Northern Chile, which, although long and narrow, washed by the broad Pacific Ocean, is without rain. South America has no other wholly rainless region, so far as is known. A part of this region would lie between the equatorial belt of rain and the southern extra-tropical one and never be covered by either; but the volume of N. E. trades from the Atlantic, although from the make of the land not concentrated to so great an extent as the volume of S. E. trade on the north and therefore not so liable to hurricanes and other violent storms, is yet sufficiently so to carry the southern line of the equinoctial rainy belt down in winter to the summer line of extra-tropical rains and give a supply of rain to all the continent; leaving no strictly rainless region south of the equatorial rainy belt and east of the Andes. Those mountains, however, present a barrier to its south-western progress which it doubtless passes to some extent but deprived of its moisture and unable to supply the rainless coast region of Peru, Bolivia and Northern Chile. There is, therefore, a portion of this rainless line of coast which is within the region of extra-tropical rains, over which a portion of the N. E. trades of the Atlantic, as a counter-trade, should or do, curve and where there should therefore be extra-tropical rains. It is washed by the Pacific, an evaporating surface and westerly and south-west breezes are drawn in from that ocean over it. Why then is it rainless?The only reason which can be assigned why rain does not fall there is that the high mountain ranges of the Andes intercept and perhaps in part divert the counter-trade and deprive that portion of it which passes them, of its moisture, by that reciprocal action of opposite polarities which takes place whenever and wherever the trade approaches so near the earth; and it curves over the narrow line of coast with the feeble condensation and imperfect forms and varied colouring which mark so peculiarly the rainless clouds of that region. (See Stewart’s Journal of a Voyage to the Sandwich Islands, page 72.)Again, it is estimated and on reliable data, that twelve perpendicular feet of water are annually evaporated from the surface of the Red Sea, between Nubia on one side and Arabia on the other; yet they are both rainless countries, except so far as the inter-tropical belt of rains extends up on to a small portion of them. The moisture of evaporation, floated up from a surface covered by the surface-trade is invariably so combined as to remain uncondensed till it has passed south into the equatorial rainy belt and over to the opposite hemisphere and been exposed to the currents of an opposite magnetism.Again, the N. E. trades extended up in summer over the Mediterranean Sea, an evaporating surface, blow over the Barbary States in June and July but furnish no rain. And so of the S. E. or N. E. trades which blow over Brazil and other countries in the absence north or south of the tropical belt of rains.It is obvious from these facts; and more like them might be cited; that mere evaporation, however copious or long continued, does not make the storm or shower in the locality where it takes place and without the existence and influential agency of a counter-trade; and that reciprocal action, whatever it may be, that takes place between it and the earth.Again, our own experience is conclusive of this. We have no surface-trade north of 30° and yet a long drought and great evaporation may follow a wet spring. Belts of droughts and frequent rains occur every year in different portions of the country side by side and the dividing line follows the course of the counter-trade and is sometimes distinctly marked for weeks. When a change occurs in the counter-trade, whether from causes existing there or the influence of terrestrial magnetism (in relation to which we shall inquire hereafter), showers form or storms come on: until it does they will not. Efforts at condensation will occasionally appear but they will be feeble and ineffectual and occasion a repetition of the axiom that “all signs fail in a drought.” And we may know it from direct observation.The first indications of a storm and of most if not all showers, are observable in the counter-trade. These indications, so far as they are visible, are of course to be looked for in the west; although the direction and character of the surface-winds are often indicative of these changes when not visible at the west as we shall see.The indications are those of condensation and vary very much in different seasons of the year. It is not my purpose in this place to examine them particularly. They will be alluded to hereafter under the head of prognostics. Suffice it now to say, then, that whether it be the long threads or lines of cirrus which occur in the trade in the winter after a period of severe cold, following the interposition of a large volume of N. W. cold air and the elevation of the counter-trade; or the forms of cirrus which occur at other times and other seasons; or whether it be the ordinary bank at night-fall, or the evening condensation which makes the “circle” around the moon, or the morning cirro-stratus haze which gradually thickens, passes over and obscures the sun, all which may be followed by the easterly scud and winds: they are alike condensation in the trade, the advance or forming condensation of a storm or showers.The state of the weather, whether hot or cold, is extensively affected by this trade current. As we have already suggested, the mere presence of the sun in its summer solstice, or its absence in winter, is not an adequate cause of all the sudden and various changes to which we are subject. The state of the counter-trade, which is always over, or within influential distance of us and sometimes probably in contact with us; the nature of the surface-winds which it is at any given time creating and attracting around us and the electric condition of the surface-atmosphere induced by it, or by the immediate action of the earth’s magnetism, produce those sudden changes which mark our climate. When no intervening surface-winds elevate it above us and there is no storm or other condensation within influential distance, it induces the gentle balmy S. W. wind of spring; the cooling S. W. wind of summer; the peculiar Indian summer air of autumn, or the comparatively moderate, although cold, open weather of winter. If there be a partial tendency to condensation in it, the cumuli form under the magnetic influence excited by the sunbeams from ten to three o’clock in the day and float gently away to the eastward, disappearing before night-fall. If the disposition to condensation is stronger, whether inherent or induced by an increased local activity of terrestrial magnetism, these cumuli will increase toward night-fall, or earlier and terminate in showers; and if it is in a highly electrical state, the still oppressive sultriness which precedes the tornado and that devastating scourge may appear. If this disposition to condensation becomes extensive, cirri form and run into cirro-stratus, or they extend, coalesce and form stratus; the surface-wind will be attracted under them, the thermometer fall in summer or rise in winter and a storm begin. Intense action and sudden cold may exist in and under this counter-trade over the southern portion of the country, while all is calm, warm and balmy at the north. Heavy snow storms sometimes pass at the south when there are none at the north and a corresponding state of the weather follows. If a large body of snow fall at the north, the winter is cold, regular and “old fashioned;” if little snow falls at the north and more at the south, the winter at the north is open and broken. I have known the ice make several inches thick at Baltimore and Washington, when none could be obtained for the ice-houses on the Connecticut shore of Long Island Sound. In short, although heat and cold are mainly dependent upon the altitude of the sun, aided by the other arrangements we have alluded to, yet the counter-trade and the reciprocal action which takes place between it and the earth, are most powerful agents, mitigating the rigours of winter, bringing about the changes from cold to warm weather which the sun is too far south to produce. And on the other hand, by this reciprocal action, producing the electrical phenomena, the gusts, the tornadoes, the hail storms and the cool seasons of summer and the period of intense cold in winter.All our surface-winds, except the light, peculiar W. S. W. wind which is felt where the counter-trade is in contact with the earth and which is a part of it and perhaps the genuine N. W. wind which is very peculiar, are incidents of the trade and are due to its conditions and attractions. We have already said this was true of the easterly wind and scud of a storm; it is alike true of all. The storm winds east of the Alleghenies are usually, though not always, from the eastward. They are sometimes from the southward, as they doubtless are still more frequently in the interior of the continent.There is occasionally a southerly afternoon wind, followed by short rains in spring and fall, or a succession of showers in summer, which is rather a precedent wind than a storm wind; blowing toward and under an advance portion of the storm at the north and hauling to the eastward when the rain sets in, or to the westward when the showers reach us.When there are no storms, or showers, or inducing electric action in the counter-trade, within influential distance to disturb the surface atmosphere, it is calm. If a storm approaches, or forms within inducing distance, the surface atmosphere is affected and attracted toward the storm, from one or more points and “blows,” as we say, toward and under it. It commences blowing first nearest the storm and extends as the storm travels, or becomes more intense and extends its inducing influence. I have repeatedly noticed this in travelling on steamboats and rail roads running toward or from and in several instances through a storm and telegraphic notices and other investigations prove it. The point from which the surface atmosphere is attracted and blows, depends very much upon the position of the storm in relation to bodies of water and the point of observation and its shape; and the force with which it may blow will depend much upon its intensity.Let us take an instance or two by way of illustration of all these points; and as I have given instances of summer in the introduction, we will take those of winter. It is January of an “old fashioned winter;” the snow is about three feet deep in Canada, about one foot in Southern New York and a few inches in Philadelphia and so extends west to the Alleghenies at least. For several days the sky has been clear, the thermometer rising in the day-time, in the vicinity of New York to about 25° Fahrenheit, falling at night to about 6°, with light airs from the N. W. during the middle and latter part of the day; the counter-trade and the barometer both running high; cold but pleasant, steady, winter weather. There is a warm south-east rain and thaw coming, as one or more such almost invariably occur in January. How coming?The sun is far south and shines aslant but through a pure and windless atmosphere; it has tried for several days to melt the snow from the roof; a few icicles are pendant from the eaves; but the body of the snow is still there. How can a thaw come?Not from the sun, surely?No, indeed, not from the action of the sun directly, upon our country, nor from the Atlantic or the Gulf Stream which is off our coast. But a portion of the current of counter-trade is coming, heated by his rays and the warm water in the South Atlantic, in an intense magneto-electric state, capable of inducing an electro-thermal change in the surface atmosphere which it approaches and of being reciprocally acted upon by the north polar terrestrial magnetism. It is now over Northern Texas and Western Louisiana, it will be here the day after tomorrow. The day passes as the day previous had passed; the sleigh-bells jingle merrily in the evening; the moon shines clear all night; the storm is coming steadily on but its influence has not reached us and the morning and midday are like those which preceded it. As nightfall approaches, however, the thermometer does not fall as rapidly as on the day previous; the sun shines dimly and through lines of whitish cirrus cloud extending from the horizon at the west, appearing darker as the sun descends and shines more horizontally through them; perhaps mainly in the N. W.; and which extend up and over toward the E. N. E. The air next the earth begins to feel raw; it is changing, not from warm to cold but electrically from positive to negative; and dampening, from a tendency to condensation by induction, as we shall see; the same condensation which in warm weather may be seen on flagging stones and walls and vessels containing cold water. The advance cirrus condensation of the storm is over us and affecting us; the earth too is affecting the adjacent atmosphere by action extended from beneath the storm. Still there is no wind, although sounds seem to be heard a little more distinctly from the east and so ends the day. Evening comes and the moon wades in a smooth bank of cirro-stratus haze, with a very large circle around her; the cirrus bands of haze have coalesced and formed a thin stratus. The storm is coming steadily on, its condensation is seen to be thicker as it approaches, it is now raining from one hundred to one hundred and fifty miles to the west but we do not know it.That it is about to storm all believe, for all are conscious of a change. The candle if extinguished will not relight as readily, if at all, on being blown; there is a crackling almost too faint for snow in the fire; the sun did not set clear; the old rheumatic joints complain and the venerable corns ache.Morning comes and the storm is on. The wind is blowing from the S. E., the scud are running rapidly from the same quarter to the N. W., the thermometer continues rising and it rains. The storm has reached us and the thaw has commenced. Gradually, as the densest portion of the storm cloud reaches us, it darkens; the scud are nearer the earth and run with more rapidity; the rain falls more heavily and continuously and by the middle of the day a thick fog has enveloped the earth; the wind is dying away and the trade itself, with its southern tendency to fog, has settled near us; the barometer has fallen, the thermometer is up to fifty degrees, the water is running down the hills, the snow is saturated with water and is disappearing under the influence of the fog, the rain and the warm air. Evening comes; the south-east wind and the rain have ceased; the rain clouds have passed off to the eastward; the fog has followed on and disappeared; there is a light trade air from the S. W.; the moon shines out and a few patches of stratus, broken up into fragments and melting away, are following on in the trade: the storm is past.Hark! to the tones of Boreas as he bursts forth from the N. W. and rushing, whistling, howling, dashes on between the trade and the earth, following the storm. Now the barometer rises rapidly, the thermometer falls and in an incredibly short time all is congealed and cold and wintry as before. The cold N. W. wind has again interposed between the trade and the earth; the trade is elevated a mile or more above it and is entirely free from its influence and from condensation; the deep blue of a sky “as pure as the spirit that made it” is over us and steady winter reigns again.It is obvious that there was nothing in the action of the sun upon our snow-clad country, to induce the thaw or the storm. It began, continued, approached and passed off to the N. E. in the counter-trade. The S. E. wind which existed everywhere within its influence: in the interior States, Missouri, Illinois, Indiana, Ohio, Michigan and in Canada, as well as upon the Atlantic coast, commencing in the former earlier than upon the last, was the result of its induction and attraction. Of the N. W. wind that followed we shall speak hereafter. If any one doubts whether this be a true sketch let him examine the investigation of a storm published by Professor Loomis, or observe for himself hereafter. If, however, the storm of Professor Loomis is referred to, it should be remembered that his notes show the occurrence of a slight distinct snow storm at the N. W. stations one day in advance of the principal storm. The latter appears first as rain at Fort Towson, on the nineteenth, moving north and curving to the east; its centre passing near St. Louis and south of Quebec and the whole storm enlarging as it advanced.Take another instance. Since the thaw it has not been quite as cold as before; but the rain-soaked snow is hard and solid, the ground, where the snow was blown or worn off, icy and slippery; the thermometer falls during the night to about 12° and rises to about 30°; the sun makes no impression upon the snow; the firmament is of the deepest blue, the borealis at night vivid. “O, for a storm of some kind, to mitigate the still severe cold;” for the thaw has made us more sensitive and storm winds do blow warm in their season. But patience, it will come. Another day, or two, perhaps, pass: the sun rises as usual, the thermometer has the same range still. “Long cold snap,” we exclaim; “how long will it last?”A change is coming but this time it will snow. About an hour or two after sunrise the cirrus threads are discoverable again in the west but now they are most numerous in the S. W. As the day passes on they thicken and advance toward the E. N. E., the sun begins to be obscured, the thermometer rises and it slowly “moderates.” There is a snow storm approaching from the S. W.But the thermometer rises slowly; it must get up to 26° or 28° before it can snow much. I have known in one instance, at Norwalk, a considerable fall of snow, although much mingled with hail, when the thermometer stood at 13° above zero and one, a moderate fall, some two inches, with it at 24° but these were exceptions. The snow range of the thermometer on the parallel of 41° north latitude and south of it, is from 26° to 30° above 0°; when colder or warmer it may snow to whiten the ground, or perhaps barely cover it but usually rains or hails. We have seen that in the polar regions, according to Dr. Kane, it is about zero but the rise of the thermometer there, previous to the snow, was about the same as here, i. e., from 15° to 25°. This fact is instructive. Since the foregoing was written and on the 7th of February, 1855, a snow-storm of considerable length set in, with the thermometer at 5° and continued more than twenty-four hours, the thermometer gradually rising. The snow was very fine, like that described by Arctic voyagers as falling in extreme cold weather.As the dense and darker portions of the storm approach and although the sun is obscured and the ground frozen, it continues to moderate and at evening, when the thermometer is up to 28° and the dense portion of the storm has reached us, gently and in calmness the snow begins to fall. Perhaps a light air following the storm, or the presence of the trade near the earth, at first inclines the snow-flakes to the eastward. This is frequently so at the commencement of snow storms. Ere long, however, the wind rises from the N. E. and the snow is driven against the windows, rounded and hardened by the attrition of its flakes upon each other, in their descent through the eddying and opposite currents. The next day we rise to witness a heavy fall of snow, perhaps and a continued driving N. E. storm, in full blast; the snow whirling and settling in drifts under the lee of every fence or building.Can it be, you ask, that this driving wind is but an incident of the storm?the result of attraction, while the storm clouds are sailing quietly and undisturbed on in the counter-trade above, directly over the gale which is blowing below?It is even so. Nor has it “backed up,” as it is termed by those who have ascertained that it has commenced snowing first and cleared off first, at a point west of them. You saw, or might have seen, the cirro-stratus cloud passing to the E. N. E. in the afternoon and until the snow-flakes filled the air and the clouds became invisible. You may still see that the wind will die away before the storm breaks and “come out” gently from the S. W., unless it should back into the northward and westward and in either event you may see the last of the storm clouds, as you did see, or might have seen the first of them, pass to the eastward. Toward night the wind dies away and the storm passes off abruptly, or the sky becomes clear in the N. W. Now you may see the smooth stratus storm cloud, continuous, or breaking up into fragments and passing off to the east, even at the edge which borders the clear sky in the west or north-west, to be followed that evening or the next day, by the north-west wind and its peculiar fair-weather scud.I have given these as instances illustrating the manner in which rain and snow storms originate the surface easterly winds in winter. But it must not be supposed that they commence with precisely the same appearances in every case in winter; much less in summer. There is very great diversity in this respect, in different seasons and in different storms during the same season. A great many different and accurate descriptions might be given, if time and space would permit, which all would recognize as truthful. Very frequently in summer and sometimes in winter, the wind will set in from the eastward and blow fresh toward a storm, before the condensation in the trade, which forms the eastern and approaching edge of the storm, has assumed the form of a distinct cloud. Not infrequently, when it is calm next to the surface, a narrow stratum of easterly wind, a half a mile or a mile above the earth, may be seen with a continuous fog, condensing but not in considerable patches like the usual scud, running with great rapidity toward the storm. Such a stream of fog blew with great rapidity for thirty-six hours toward the storm which inundated Virginia and Pennsylvania, in 1852 and carried away the Potomac bridge at Washington. Such a stream of fog was visible the evening before the great flood of 1854, which inundated Connecticut and curried away so many railroad and other bridges. I have also seen such a stream of fog running at about the same height, when it was calm at the surface, from the S. W. toward a violent storm which formed over central New England; and from the north toward a heavy storm passing south of us. Such strata form, as far as I have been able to discover, the middle current of storms which are accompanied with very heavy falls of rain. These double currents are much more common than is supposed. East of the Alleghenies, short and heavy rain storms, which commence north-east, hauling to the south and lighting up about mid-day after a very rainy forenoon, frequently have a S. E. or S. S. E. middle current of this character, which involves the whole surface atmosphere when the storm has nearly passed and the N. E. wind dies away and the wind seems to haul to the S. S. E. and S.; so that it is rather the prevalence of a different and coexisting current, than a hauling of the same wind, which marks the period of lighting up in the south.Sometimes the easterly wind will set in and blow a day or two before the border of the storm reaches us. Sometimes the storm is passing, or will pass, in its lateral southern extension, south of us and the condensation in the trade extends over us sufficiently dense to induce an easterly current beneath it but not dense enough to drop rain and then we have a dry north-easter. I can not, within the limits I have prescribed, allude to all the peculiarities attending the induction and attraction of an easterly wind, by the storm in the counter-trade. They are readily noticeable by the attentive and discriminating observer and their existence and cause is all with which I have to do at present.Winds from the north, or any point from N. N. E. to N. N. W., are comparatively infrequent in the United States, east of the Alleghenies; though it is otherwise in the vicinity of the great lakes.Sometimes the wind “backs,” as sailors term it, during a N. E. storm, from the N. E. through the N. N. E., N. and N. N. W. to N. W. When this takes place, it is toward the close of the storm. Occasionally, though very rarely, it continues to storm after the wind has passed the point of N. N. E. and until it gets N. W. I have known a few instances in the course of thirty years and but a few. They are exceptions; rare exceptions. When the wind thus backs from the N. E. to the N. W. through the N., you may be very certain that the body of the storm, or at least the point of greatest intensity and greatest attraction, is at the time passing to the southward of you. This is most commonly the course of the wind when the storm extends far south and lasts several days and does not extend north far, or if so, with much intensity, beyond the point of observation. The change of the wind is explained by the situation of the focus of intensity and attraction, to the south of the observer and its passage by on that side.Probably in locations further north and (as I think I have observed) south of the lakes, it may be more frequent than upon the parallel of 44° east of the Alleghenies (which is as far north as I have observed), inasmuch as the further north the locality, the more likely storms and other disturbances in the counter-trade will be to pass to the southward of it.Between the N. E. and S. E. the wind may blow from any point, before and during storms and in a clear day in the morning, as a light variable breeze, or, after mid-day, toward approaching showers. I have known it blow all day during a storm from due east; to change back and forth between south-east and north-east and to blow for hours from any intermediate point; as different portions of the storm were of different intensity and exerted a more or less powerful inducing influence; and doubtless this often takes place at sea. It depends upon the situation of the focus of attraction of the storm, its shape relative to the particular locality and with reference to the atmosphere east of it and peculiar local magnetic action; or, as is sometimes the case in low latitudes, is owing to the fact that the storm is made up of many imperfectly connected showers, which have different force and induce changeable and baffling winds.The inducing and attracting influence of the approaching storm is exerted sooner and with most force, upon the surface atmosphere, over bodies of water like the ocean and the lakes. Thus, the wind will set from the eastward toward an approaching storm out upon Long Island Sound, for hours before it is felt upon either shore; and when all is calm in the evening on land and often before the moon forms a halo or circle in the milky condensation of the approaching storm, or any sign of condensation is visible, the breaking of the waves upon the shores may be heard. Doubtless this may be observed on the shores of the Atlantic at other points.This power of attracting the surface atmosphere from bodies of water like the ocean and the great lakes, will account for two apparent anomalies, mentioned by Mr. Blodget in a valuable and instructive article read to the Scientific Convention, in 1853, regarding the annual fall of rain over the United States.First; the influence of mountains in extracting the water from the atmospheric currents which pass over them, is well known and readily explainable. Mr. Blodget, however, found that the source of our rains, whatever it might be, when it reached the Alleghenies, was so far exhausted of its moisture that those mountains extracted less from it than fell to the westward, by some five to ten inches annually; and that the fall of rain upon them was less than upon the Atlantic slope eastward of them, to the ocean. This does not accord with observation elsewhere but is easily explained. As the storm approaches the ocean, it attracts in under it the surface atmosphere of the ocean, loaded with vapour, condensing in the form of fog and scud, as it becomes subject to the increasing influence of the storm. Although the scud and fog would not of itself make rain, it aids materially in increasing the quantity of that which falls through it. The drops, by attraction and contact, enlarge themselves as they pass through, in the same manner as a drop of water will do in running down a pane of glass which is covered with moisture. The small drop which starts from the upper portion of a fifteen-inch pane, will sometimes more than double its size before it reaches the bottom. It is by this power of attracting the surface atmosphere, which contains the moisture of evaporation, under it and inducing condensation in it, that the moisture of evaporation which rarely rises very far in the atmosphere is made to fall again during storms and showers. This attraction of a moist atmosphere from the ocean accounts for the excess of rain on the east of the Alleghenies, compared with its fall upon them. So the great valley of the Mississippi is comparatively level and less of its water runs off than of that which falls upon the Alleghenies. There is, therefore, more moisture of evaporation in the atmosphere of the former to be thus precipitated and add to the annual supply of rain upon that valley and it exceeds that which falls upon the Alleghenies. Those mountains, too, are elevated but about 1,500 feet above the table-lands at their base and exert little influence on the counter-trade. If they, were 6,000 or 8,000 feet high, a different state of things would exist.Second; Mr. Blodget found the quantity of rain which fell in Iowa and to the south and west of the lake region, to be greater than fell over the lake region itself. This is doubtless in part owing to the same cause. The counter-trade, in a stormy state, attracts the surface atmosphere from the lake region, with its evaporated moisture, before it arrives over it and therefore more rain falls S. W. of the lake region than upon it. This power of attracting the surface wind of the ocean in under it, produces the heavy gales which affect our coast and which are rarely felt west of the Alleghenies to any considerable degree; and a storm coming from the W. S. W., extending a thousand miles or more from S. S. E. to N. N. W., may have the wind set in violently at S. E. on the southern coast first and at later periods, successively, at points further north and thus induce the belief that the storm travelled from south to north.Mr. Redfield finding that some of the gales which he investigated, particularly that of September 3d, 1821, did not extend far inland and commenced at later periods regularly, at more northern points, concluded that the gale travelled along the line of the coast to the northward. In this and in relation to the storm of 1821 (and perhaps some others), he has been deceived. My recollections of that storm are accurate and distinct. But I shall recur to this again when I come to speak of his theory.Toward storms, or belts of showers which would be storms if it were not summer and the tropical tendency to showers active in the trade, which pass mainly to the north of us, or commence north and pass over us, condensing south while progressing east, the wind may commence blowing before the body of the storm reaches us, from any point between south by west and south east, particularly in the summer season and in the afternoon. When the rain in a storm of this character sets in, in the night, it will sometimes haul into the S. E., if the focus of attraction be situated north of us and so remain until just before the storm is to break.There are, however, a class of southerly summer winds which deserve more particular notice. For two or three months in the year; say from the middle of June to the 20th of August; storms on the eastern part of the continent, except in wet seasons, are rare and most of our rain is derived from showers. During these periods belts of drought are frequent, sometimes in one locality and sometimes in another, extending with considerable regularity from W. S. W. to E. N. E. in the course of the counter-trade, while rain falls in frequent and almost daily showers to the northward or southward of them. If the daily rains are at the north, over the belt of drought, S. S. W. and S. W. by S. winds blow, sometimes with cumuli or scud, during the middle of the day and afternoon, to underlie the showery counter-trade on the north of the line of drought. Thus, sometimes nearly every day for several days, the evaporated moisture of the dry belt will be carried over to increase the store of those who have a sufficient supply without it. During the latter part of the afternoon the clouds in the west may look very much like a gathering shower but the attractions of the counter-trade, between fifty to two hundred miles to the north, will absorb them all and at nightfall the wind will haul to the S. W. on a line with the counter-trade and die away.If there be a drought on any given line of latitude and frequent showers or heavy rains at the south of it, although there may not be a like surface-wind, with cumuli and fog, blowing from the north toward it, yet a general, gentle set of the atmosphere, from the N. N. W., or N. W., or other northerly point, toward the belt of rains, some distance above the earth, will often be observable, with a barometer continually depressed and perhaps a cool atmosphere.During set fair weather, when the attracting belt of rains is far north, on the north shore of Long Island Sound, the wind, like a sea breeze, will set in gently from about S. S. E. or S. by E. in the forenoon, blowing a gentle breeze through the day and hauling to W. S. W. on a line with the trade at nightfall and dying away. During a drought I have known this to happen for seventeen successive days. It is obvious to an attentive observer that this is the result of the influence of the sun in exciting the magnetic influence of the earth and producing a state of the trade not unlike that which induces the formation of cumuli and which attracts the surface atmosphere from the Sound in over the land: for the tendency to cumulus condensation precedes the breeze and the breeze is often wanting in the hottest days where no such tendency to the formation of cumuli exists. The same is true of sea breezes elsewhere. They do not blow in upon some of the hottest surfaces. Where they do exist, they do not always blow but are wanting during the hottest days; and careful observers have identified their appearance with the formation of cumuli, or other condensation, upon the hills inland. They are not, therefore, the result of ascending currents of heated air.The received theory regarding sea and land breezes is a mistaken one in another respect. There is no such thing as a land wind corresponding in force to and the opposite of, the sea breeze; occasioned by the comparative warmth of the ocean. These breezes blow mainly within the trade-wind region. Of course they are either beneath the belt of rains or the adjoining trades. They are said to be and doubtless are, most active and strongly marked on lines of coast, particularly the Malabar coast and where the trade-winds are drawing usually from them. In the day-time, when the action of the sun increases the action of the magnetic currents upon the land, or there are elevations inland which approach the counter-trade and especially if it is elevated near the coast, as the Malabar coast is by the Ghauts, the attraction of this atmosphere over it reverses the trade, or inclines it in upon the land and it blows in obliquely or perpendicularly, according to the relative trending of the coast and the direction of the surface-trade. Thus, where islands are situated within the range of the trades, the latter will be reversed during the day on the leeward side but continue to blow as land winds during the night. So they are sometimes deflected in upon the land on the sides, during the day and in like manner return to their course in the night. So, too, the north-east trades of Northern Africa, are occasionally (though feebly where the coast is flat) deflected during the day-time and blow in as N. W. winds. Upon the southern coast of Africa the S. E. trade is deflected and blows in as a S. W. wind. Upon the south-western coast of North America, the N. E. trades are deflected in like manner and so are the S. E. trades upon the western coast of South America. Where the coastal mountain ranges are very elevated, as upon the western coast of the American continent, this attracting influence and consequent deflection extends to a considerable distance seaward and hence the westerly winds of California, etc. It must be understood that we are now speaking of the winds which blow within the range and during the existence of the trade-winds or the presence of the dry belt; for the trades are not always perceptible on the land. Captain Fitzroy thus describes the sea breezes of the western coast of Peru, at 23° south latitude. “The tops of the hills on the coast of Peru are frequently covered with heavy clouds. The prevailing winds are from S. S. E. to S. W., seldom stronger than a fresh breeze and often very slight. Sometimes during the summer, for three or four successive days, there is not a breath of wind, the sky is beautifully clear, with a nearly vertical sun. On the days that a sea breeze sets in, it generally commences about ten in the morning, then light and variable but gradually increasing till one or two in the afternoon. From that time a steady breeze prevails till near sunset, when it begins to die away and soon after the sun is down, there is a calm. About eight or nine in the evening light winds come off the land and continue till sun-rise, when it again becomes calm until the sea breeze sets in as before.”To illustrate this further, I take the following letter from Professor Espy’s Philosophy of Storms:Clinton Hotel, N. Y., Dec. 20, 1839.To Professor Espy,Dear Sir; Understanding you are desirous of collecting curious meteorological facts, I take the liberty of communicating to you what I saw in the month of December, 1815, at the Island of Owhyhee. I lay at that island in the Cavrico Bay,[3] in which Captain Cook was killed, three weeks and every day during that time, very soon after the sea breeze set in, say about nine o’clock, a cloud began to form round the lofty conical mountain in that island, in the form of a ring, as the wooden horizon surrounds the terrestrial artificial globe and it soon began to rain in torrents and continued through the day. In the evening the sea breeze died away and the rain ceased and the cloud soon disappeared and it remained entirely clear till after the sea breeze set in next morning. The land breeze prevailed during the night and was so cool as to render fires pleasant to the natives, which I observed they constantly kindled in the evening. I was particularly struck with the phenomena of the cloud surrounding the mountain, when none was ever seen in any other part of the sky and none then till after the sea breeze set in, in the morning, which it did with wonderful regularity. The mountain stood in bold relief and its top could always be seen from where the ship lay, above the cloud, even when it was the densest and blackest, with the lightning flashing and the thunder rolling, as it did every day. I passed up through the cloud once and I know, therefore, how violently it rains, especially at the lower side of the cloud. This rain never extends beyond the base of the mountain;[4] and all round the horizon there is eternally a cloudless sky. The dews, however, are very heavy and there seems to be no suffering for want of rain. That this state of things continues all the year, I have no doubt, from what an American, by name Sears, who had spent four years there, told me; he had seen no change in regard to the rain.Caleb Williams.Providence, R. I.Similar citations might be made to show that the sea breeze is induced by the same cause which forms the clouds over the land; that it is frequently wanting for three or four days under a vertical sun and that the land breeze blows gently and not with corresponding force where there is no surface trade, or where it is deflected, not reversed.A succession of showers passing across the country to the north, within one hundred to one hundred and fifty miles, almost always produces a southerly wind to the southward of them. There is more that is peculiar about these belts of showers. Although they consist of large highly-electrified cumuli, there is a strong tendency to cirro-stratus condensation in the lower part of the trade over them; and it is that condensation rather than the cumuli, which attracts the surface atmosphere from the south. They would be storms, if the atmosphere had not a summer-tropical tendency to showers. There is, too, a tendency in these belts to extend to the south and it is generally, as far as I have observed, the extension southerly of those belts, by the formation of new showers which terminate the “hot spells” or “heated terms” of mid-summer. The very oppressive and fatal one of the summer of 1853, was, in character, a type of all; although exceeding them in severity. The first three or four days were calm, hot and smoky; an appearance which attends all similar periods more or less, refracting the red ray of the light and giving the sun a peculiar dry-weather, red appearance. (This smoky haze is usually atmospheric and occasionally seen even in March, although not infrequently fires in the woods fill the air with actual smoke and very much increase it and when this is so, the odour of the smoke is often perceptible.) Then we began to have a fresh south-west by south breeze in the day-time, hauling to the south-west and dying away at nightfall. The next day, the tendency to condensation and consequent belt of showers having extended further south and approached nearer to us, the S. S. W. wind blew fresher toward it and did not die away at nightfall. During the evening the reflection of the lightning playing upon the tops of the thunder clouds, just visible at the north (heat-lightning, it is termed, because supposed to be unaccompanied by thunder but in reality lightning reflected from clouds at too great a distance for the thunder to be heard) and the continuance of the southerly wind after nightfall, gave sure evidence of the coming showers the next day and an end of the excessive heat for that time. So ended both of those long-to-be-remembered “heated terms” of 1853.
As far as I know Comment Boxes have a limitation –I have no idea in the Post area yet..
THis is the first chapter. I don't know how much of it Opera will let me post so here goes:
That was 43 "Page Downsd" I think I will be able to get the lot in in suitably sized lumps but I am not sure how my avid fans will feel about that though.Stick it to 'em Weather, m'boy. Those that fall can pick it up later. He that gathers with me want's his lumps read.
CHAPTER VIII.It is exceedingly desirable, in a practical point of view, to understand the precise character of the reciprocal action which takes place between the earth and the counter-trade and produces the varied phenomena which mark our climate. We have seen that the same laws, other things being equal, operate everywhere and that analogies may be sought in the character of those phenomena elsewhere, under the same, or different, modifying circumstances. Looking, therefore, at the magneto-electric movable machinery as a whole and its influence upon the atmospheric circulation and conditions, we find many facts which point to a primary action in the counter-trade and others that point as significantly to a primary local-inducing-action in the earth. Let us briefly review those to which we have alluded and advert to some others and see what solution of the question they will justify:The belt of inter-tropical rains appears to be, in width and amount of precipitation and annual travel north and south, proportionate to the volume of trades which blow into it, the quantity of moisture they contain and the elevation of the surface over which they meet.South America is the most thoroughly-watered country within the tropics, except, perhaps, portions of Hindustan, Burmah, Siam, etc., on south-eastern Asia. The contrast between both and Africa, as far as explored and as shown by its rivers, is most obvious. The Amazon, alone, delivers more water to the ocean than all the rivers of Africa.Of the width of the belt of rains over Africa, in the interior, we know little. Its northern extension is less, by from 7° to 10°, than the same belt over South America, the West Indies and Mexico. Probably its southern is also. Upon South America, the southern edge is carried down to Cochabamba, in latitude 18° and probably to 25°, to the northern edge of the coast-desert of Peru, while it is rarely, if ever, found over the Atlantic below 7°, a difference of 12° to 20°. Over South America, too, the quantity of water which falls is also vastly in excess of that which falls upon the Atlantic. The main cause of these differences is obvious. The N. E. counter-trades which blow over Africa, originate on a surface which is rainless, as eastern Sahara, Egypt, Arabia, etc., or subject to a dry season by the northern ascent of the southern line of the extra-tropical belt, as the Barbary States, Syria, Persia, etc. and their supply of moisture is necessarily scanty. On the south, the S. E. trades originate, in part, upon the eastern portion of southern Africa, and, in part, upon the Indian Ocean and from the latter source and a portion of the Mediterranean, doubtless most of the water which falls upon Central Africa, is derived.The N. E. and S. E. trades which blow into the inter-tropical belt upon the eastern portion of the Atlantic, originate upon similar surfaces and with like effect. Thus, the S. E. trades, in summer, are from the Southern portion of Africa and the N. E., in part, from the Mediterranean; and, in winter, the N. E. from the deserts, Senegambia, Nigritia, etc. and the S. E., owing to the narrowing of the African continent, mainly from the South Atlantic and Indian Oceans. Going west, the belt widens and its range increases until the Andes are reached; but under their lee, on the western side, a totally different state of things is found and the belt of the coast becomes broken and irregular, as we have seen in the citation from Maury.The width, extension and excessive precipitation of the belt, over South America, follow the same law. The South Atlantic widens out by the trending of the coast to the S. W. and furnishes a large area for the unobstructed formation and evapourative action of the S. E. trades. So the trending of the coast to the N. W., from 5° south to the northward, opens a large area for a like formation and action of the N. E. trades. No correspondingly favorable circumstances exist any where, except, perhaps, around Hindustan and there the fall of rain is very excessive in some places, as on the Kassaya hills, to the extent of 400 inches per annum. In addition to this, the magnetic line of no variation and of greater intensity, which runs from our magnetic pole, obliquely, S. S. E., to its opposite and corresponding pole in the southern hemisphere, enters the Atlantic on the coast of North Carolina and traverses it and the eastern portion of South America, through the whole trade-wind region. The table-lands and slopes and high mountain peaks, meet the trades successively, as they go west and the latter wrench from them, to an unusual extent, their moisture; depressing the line of perpetual snow, by an increase of quantity on the eastern sides, several thousand feet, as it is for a like cause depressed on the southern side of the Himmalayas. On the eastern slopes and tops of the Andes, as we have seen and owing to their elevation, falls the moisture which, according to the working of the machinery and the law of curvature, should bless the coast line of Peru and northern Chile, the eastern Pacific, northern Mexico, California, Utah and New Mexico; and, while the Andes stand, the curse of comparative aridity must rest upon them all.Southern Chile and western Patagonia are supplied by the N. E. trades, which originate in the West Indies, the Gulf of Mexico and the Caribbean Sea and the Pacific, off Central America, in the neighbourhood of the Bay of Panama. But there, again, the same effect of elevation is seen. The mountain slopes of southern Chile and Patagonia are abundantly supplied and their mountain ranges are drenched with rain, while eastern Patagonia and southern Buenos Ayres, under their lee, are comparatively dry. So the S. E. trades, which originate off the western coast of South America, curve in upon and aided by the oceanic currents, supply, abundantly, the N. W. coast of this continent, north of California; and there, too, the coast and its elevated ranges, receive, as we have seen, a very large proportionate supply of their moisture. Substantially, the same state of things, as far as circumstances permit, is reproduced upon Malaysia, Hindustan, etc. and the interposition of arid New Holland upon the evaporating trade-surface may be distinctly traced upon south-western Asia. Deserts abound there; the Caspian Sea receives the drainage of a very large surface, without an outlet; their southern line of extra-tropical rains is carried up very far in summer and their dry season is intensely hot. (See an article in the American Journal of Science, for July, 1846, by Azariah Smith.)Another fact in this connection is worthy of a moment’s consideration. The magnetic equator, as sought by the dipping needle, is not coincident with the geographical one. Humboldt found it, on the Andes, at 7° 1′ south and it has been found still lower in the Atlantic. Over Africa it rises above the geographical equator and descends again on the Indian Ocean. About midway the Pacific, it becomes coincident with the equator of the earth again. (See diagram, on page 83.) Perhaps it is not known, with certainty, why this is so. The south pole may be situated nearer the geographical pole than the north one; but this is not believed to be so, nor could it make the difference. The greatest southern depression of the magnetic equator is found where the lines of greatest intensity and of no variation, are found; and at the more intense of these lines exists the greatest depression. From this, I think, it may be inferred that the needle is affected by the greater magnetic intensity of the northern hemisphere, to which it may yet appear the obliquity of the earth’s axis is owing. However this may be, or whatever the cause, no marked effect is produced upon the trades. The S. E. trades, by reason of the greater extent of ocean-surface on which they originate, are everywhere the most extensive, regular and forcible. The south polar waters, from which they rise, are everywhere trenching upon and overriding, the north polar ones; and thus, by a most beneficent provision, the greater portion of the habitable surface is placed in the northern hemisphere and the principal portion of the southern is left open to an extensive, active evapourative action, which supplies the northern habitable surface with a large excess of the needed moisture.The condensation and consequent precipitation, which takes place at the passing of the trades, as we have already said, over the ocean and lowlands, takes place mainly in the day-time. Upon the table-lands and mountain-ranges, it often continues during the evening and night. The morning and early part of the day, however, in tropical countries, are generally fair at all elevations.Storms also originate in the equatorial belt and issuing forth in great volume and with great intensity of action, find their way up even within the Arctic circle. Those which pass over this continent, or the northern Atlantic, generally originate in the West Indies, some of them over the Caribbean Sea, some over the islands and some over the open ocean to the east of them; and, nearly all the most violent, during the months of August, September and October. It would seem most probable that the primary action in such cases was in the trades themselves but it is by no means certain that such is the case. This is the class of storms of which Mr. Redfield has industriously investigated some twenty or more; Mr. Espy some and Lieutenant Porter two. Their course, when very violent, is often more directly north than that of storms, however violent, which originate north of the calms of Cancer, owing, perhaps, to their greater paramagnetic character. This course I have myself observed, in several instances, about the period of the autumnal equinox; never, however, more southerly than from S. W. to N. E., on the parallel of 41°, except in three, and, perhaps, four, instances, when it has been S. W. by S. to N. E. by N. I know of no class of storms in relation to which the evidence of primary action in the counter-trade is stronger than in those of the class which originate on the ocean east of the Windward Islands. But it is not satisfactory as to them. Doubtless the conflict of polarities between the passing trades is sufficient to produce the showers and rains which are ordinarily found over the ocean and lowlands, in the equatorial belt; but it is doubtful whether it is sufficient to produce such extensive, long-continued and violent action, as that which characterizes the hurricane autumnal gales.They occur, too, at the time when the whole machinery of distribution has reversed its course and is rapidly pursuing its journey south. It is a period of great magnetic disturbance, over both land and sea; of more active gales and local-increased precipitation. At the Magnetic Observatory of Toronto, Canada West, these disturbances are carefully and systematically observed and their maxima, or periods of greatest disturbance occur in April and September. (See Silliman’s Journal, new series, vol. xvii. p. 145.)The tendency to volcanic action is not as great at the autumnal, as at the vernal equinox, for the reason that most of the volcanic action of the western hemisphere develops itself now upon South rather than North America. But both exist and are active and what are improperly termed equinoctial storms and gales and rains, are proverbial during, or just subsequent to, both periods with us; as they are when the same change, called the breaking up of the monsoons, takes place in the line of magnetic intensity, over southern and eastern Asia. A volume might be filled with extracts, showing, at least, most remarkable coincidences between violent volcanic action and great atmospheric disturbance. Perhaps the increased fall of rain at and after the equinoxes, in the northern hemisphere and in certain localities subject to volcanic activity, is as strikingly illustrated by the register, kept by Mr. Johnson, on the volcanic Island of Kauai, one of the Hawaiian group, already alluded to, as in any other case, although it is by no means a singular one. The greatest fall of rain, in any month except April and October, was eight inches. In April, the fall was fourteen inches, in October, eighteen inches. Neither the equatorial, nor extra-tropical belt, were over the island during those months; but they were the N. E. trades and the result was owing solely to the interposition of high volcanic mountains, in a state of disturbance, into, or near, the strata of the counter-trade. Mr. Dobson, in stating a theory to which we shall hereafter advert, advances the following proposition:“7. Cyclones (hurricanes) begin in the immediate neighbourhood of active volcanoes. The Mauritius cyclones begin near Java; the West Indian, near the volcanic series of the Caribbean Islands; those of the Bay of Bengal, near the volcanic islands on its eastern shores; the typhoons of the China Sea, near the Philippine Islands, etc.”The peculiar stormy state of the atmosphere, over the Gulf Stream, to which I have alluded, certainly affords no evidence of primary atmospheric action. It is a body of south polar water, pursuing its way under the guidance of magnetism; maintaining its polarity; arched somewhat like the roof of a house, by the outward pressure of a cold north polar current which it has met to the east of the Banks of Newfoundland and forced to take an in-shore course to the southward and the bodies of water which the rivers discharge and a conflict with the north polar surface-winds which sweep over it and fogs, and thunder and rain, are a matter of course. Dr. Kane met a portion of this singular current in Baffin’s Bay, north of 75°, which had preserved its characteristics and a considerable proportionate excess of heat, although it probably had been around Greenland, or found its way to the west, toward the magnetic pole, through some of its northern fiords or straits. (Grinnel Expedition, p. 120.)The investigations of Lieutenant Maury show, that when the Gulf Stream turns to the eastward, crossing the lines of declination at right angles, as the counter-trades also seem to do in the same latitude, it is carried up, in summer, several degrees to the north and descends again in winter; thus demonstrating its connection with the shifting magnetic machinery which controls alike the ocean, the atmosphere and the temperature of the earth.[7]There are other irregularities which deserve to be noticed, in this connection, although the analogical evidence they afford is far from being decisive.I have already said that it was within my own observation, that alternating lines of heat and cold, as well as rain and drought, existed frequently, without regard to latitude, following, to some extent, the course of the counter-trade. Such lines have been observed by others.Thus, Mr. Espy, after describing a snow-storm, which was followed by a very cold N. W. wind, of several days’ continuance, says:“This cold air covered the whole country, from Michigan to the eastern coast of the United States, till the beginning of the great storm of the 26th January; and, what is worthy of particular notice is, that the temperature began to increase first in the north and north-west. On the morning of the 25th, in the north-western parts of Pennsylvania and northern parts of New York, the thermometer had already risen in some places 30°, and, in others, above 40°. While in the S. E. corner of Pennsylvania and in the S. E. corner of New York it had not begun to rise. The wind also began to change from the north-west to south and south-east, first in the north-west parts of Pennsylvania and New York, some time before it commenced in the south-east of those States; and, during the whole of the 25th, the thermometer, in the north of New York, continued to rise, though the wind was blowing from the southward, where the thermometer was many degrees lower.”Thus, too, Mr. Redfield (American Journal of Science, November, 1846, p. 329):“On the contrary, in times of the greatest depression of the thermometer, in numerous instances, the cold period has been found to have first taken effect in, or near, the tropical latitudes and the Gulf of Mexico and has thence been propagated toward the eastern portions of the United States, in a manner corresponding to the observed progression of storms.”This was because the cold N. W. wind which followed storms began to follow them as the storms curved and passed to the N. E.They occur in Europe also. Says Kämtz:“Such contrasts are not uncommon in Europe, and, in this respect, the Alps form a remarkable limit; for they separate the climates of the north of Europe from the Mediterranean climates, where the distribution of rain is not the same as in the centre of Europe. Hence the differences between the climates of the north and south of France. If the winter is mild in the north, the newspapers are filled with the lamentations of the Italians and Provençals at the severity of the cold.”These facts seem to indicate a primary action in the counter-trade. Probably in connection with one class of storms they do and with another do not. I shall endeavour to show the distinction when I come to the classification of storms.The difference of seasons in this country and over the entire northern hemisphere, is often very great. In a remarkable work of a remarkable man; “A Brief History of Epidemic and Pestilential Diseases,” by Noah Webster, published in 1799, 2 vols.; a history of the weather for about two centuries; 1600 to 1799 inclusive, is given generally and then in a tabular form. Those who think that every considerable extreme which occurs exceeds any thing before known, will do well to consult that work. Droughts are described, where “there was not a drop of rain for three or four months and cattle were fed upon the leaves of the trees.” Winters, so intensely cold that the thermometer fell to 20° below zero, at Brandywine; or so mild that there was little frost and people upon Connecticut River plowed their fields and the peach trees blossomed in Pennsylvania in February. These extremes generally existed in Europe and America at the same time but occasionally they were opposite and alternate. Says Mr. Webster, in summing up the facts (vol. ii. p. 12): “It is to be observed that in some cases a severe winter extends to both hemispheres, sometimes to one only and in a few cases to a part of a hemisphere only. Thus in 1607-8, 1683-4, 1762-3, 1766-7, 1779-80, 1783-4, the severity extended to both hemispheres. In 1640-41, 1739-40 and in other instances, the severe winter in Europe preceded, by one year, a similar winter in America. In a few instances, severe frost takes place in one hemisphere during a series of mild winters in the others; but this is less common. In general, the severity happens in both hemispheres at once, or in two winters, in immediate succession; and, as far as this evidence has yet appeared, this severity is closely attendant on volcanic discharges, with very few exceptions.”It will be seen that Dr. Webster (LL.D. and not M.D. and therefore the remarkable character of the work) attributes great influence to earthquakes and volcanic action. Probably he is correct in this. The present active volcanic action of the western hemisphere is nearly all within the trade-wind region, from Mexico to Peru inclusive. The West India islands are of volcanic origin and the influence of volcanic action is not confined to a concussion of the earth, or the eruption of mud and lava. Its connection with magnetic action and disturbance, is unquestionable. But whether they operate to increase or diminish the trades and the extent to which they induce violent electric action and storms within and without the tropics, is a question which further observation must determine. The ripples of the ocean, compared by Lieutenant Banvard to that of a “boiling cauldron, or such as is formed by water being forced from under the gate of a mill-pond,” are met with in the vicinity of volcanic islands, where hurricanes and water-spouts originate and have been observed to precede storms and be connected with a falling barometer. But whether they are volcanic or magneto-electric, it is difficult to determine. Dr. Webster remarks, as the result of observation, during the 17th century, that earthquakes had a N. W. and S. E. progression in the United States and especially in New England. In a recent article, Professor Dana has examined, with great ability, the general and remarkable trending of coast lines, groups of islands and ranges of mountains, from N. E. to S. W. and from N. W. to S. E. (American Journal of Science, May, 1847.)The line of magnetic intensity, which connects our magnetic pole with its opposite, is now upon this continent nearly a N. W. and S. E. line and the pole is fast travelling to the west. It may and probably will yet, be established, that there is an intimate connection between the cause of volcanic action within the earth, to which the upheaval of the N. W. and S. E. and N. E. and S. W. ranges were due and of magnetic action without and between both and the cause of the S. E. extension of our summer storms and belts of showers and barometric waves and the peculiar N. W. wind. Our limits do not permit us to pursue the subject.Much influence upon the weather has been attributed to the spots upon the sun. These spots are supposed to be breaks or openings in the luminous atmosphere or photosphere of the sun, through which its dark nucleus body is seen. Counselor Schwabe, of Dessau, has made them his study since 1826 and has arrived at some singular results. They seem to be numerous; in groups; and to appear periodically with minima and maxima of ten years. As the result of his observations, from 1826 to 1850, he gives us the following table and remarks:Year. Groups. Days showing no spots. Days of Observation.1826 118 22 2771827 161 2 2731828 225 0 2821829 199 0 2441830 190 1 2171831 149 3 2391832 84 49 2701833 33 139 2671834 51 120 2731835 173 18 2441836 272 0 2001837 333 0 1681838 282 0 2021839 162 0 2051840 152 3 2631841 102 15 2831842 68 64 3071843 34 149 3121844 52 111 3211845 114 29 3321846 157 1 3141847 257 0 2761848 330 0 2781849 238 0 2851850 186 2 308“I observed large spots, visible to the naked eye, in almost all the years not characterized by the minimum; the largest appeared in 1828, 1829, 1831, 1836, 1837, 1838, 1839, 1847, 1848. I regard all spots, whose diameter exceeds 50”, as large and it is only when of such a size that they begin to be visible to even the keenest unaided sight.“The spots are, undoubtedly, closely connected with the formation of faculæ, for I have often observed faculæ, or narben, formed at the same points from whence the spots had disappeared, while new solar spots were also developed within the faculæ. Every spot is surrounded by a more or less bright, luminous cloud. I do not think that the spots exert any influence on the annual temperature. I register the height of the barometer and thermometer three times in the course of each day but the annual mean numbers deduced from their observations have not hitherto indicated any appreciable connection between the temperature and the number of the spots. Nor, indeed, would any importance be due to the apparent indication of such a connection in individual cases, unless the results were found to correspond with others derived from many different parts of the earth. If the solar spots exert any slight influence on our atmosphere, my tables would, perhaps, rather tend to show that the years which exhibit a larger number of spots had a smaller number of fine days than those exhibiting few spots.”These observations seem to show that the spots exert no influence upon the weather and to be satisfactory. But, perhaps, they are not entirely so. No effect would, of course, be expected from day to day and perhaps the annual mean may not be seriously disturbed and yet the spots may seriously affect the seasons. Popular tradition has fixed upon certain periods, of 10, 20 and 40 years, for the return of winters of unusual severity; and the tables of Mr. Webster and other facts, show that it is not wholly without foundation. If we and those we have cited, are not mistaken in most of the views expressed, the natural effect of a partial interception or failure of the sun’s rays, by or from the existence of the spots, would be to decrease the exciting power of the solar rays upon terrestrial magnetism, and, as a consequence, the volume of the trades and their amount of moisture. This would increase the mean heat of the summer in the temperate zone; for the less the volume of trade, the less precipitation and variable wind and succeeding polar waves of cooler air and the greater mean heat. On the other hand, the same cause and the feebler heating power of the sun’s rays, would make the winters more severe, both from an absence of a portion of heat, derived directly from the sun’s rays and a less mitigating influence, from the action of the trade, by reason of its decreased volume. So, too, the absence of spots and a more powerful influence from the solar rays, may gradually carry the machinery further north in summer and further south in winter and thus make the seasons extreme without seriously disturbing the mean of the year. And both these may occur in a more marked degree over our intense magnetic area than in Europe. I am satisfied that they do so occur. That the partial failure of the sun’s rays limits the transit of the machinery and the volume of the trades during the latter half of the decade and extends the transit and increases the volume during the first half, producing an occasional severe summer drought and severe winter, in the warmest portion of the decade. And that the variations correspond with the difference in the character and number of the spots in different decades and hence the longer and shorter periods.Turning to the tables of Dr. Webster, we find that a general tendency to extreme seasons does seem to exist from the 6th to the 10th year of every decade and especially of every alternate decade. The periods of 1707-8, 1728, 1737 and 1739, 1749-50, 1758-9, 1779-80, 1798-9, are those in which the tendency was seen most decided. These tables are very general. The thermometer was not perfected till about 1700 and did not get into general use before 1750. There were very few meteorological registers kept, or accessible to Dr. Webster. Hence he was obliged to resort to such other sources of information as were open to him and such statements as he found are not always entirely reliable. The oldest inhabitant is apt to express himself very strongly respecting present extremes and fail somewhat in his recollection of those which have past. Still his tables afford general and obvious evidence of the regularity of those periodic conditions.A.D. Summer. Winter.1701 hot and dry ….1702 hot and dry ….1703 …. ….1704 dry Europe ….1705 …. ….1706 hot, dry Europe ….1707 very hot ….1708 …. very severe1709 …. ….1710 …. ….1711 …. cold Europe1712 wet England ….1713 wet England mild1714 dry and hot ….1715 dry ….1716 very dry severe1717 …. severe1718 hot and wet ….1719 …. cold America1720 dry Europe ….1721 …. ….1722 cold, wet ….1723 …. cold1724 wet England ….1725 wet England ….1726 …. ….1727 dry, hot Amer. ….1728 hot Amer. severe Europe1729 …. ….1730 …. very cold Eng.1731 …. ….1732 …. severe Amer.1733 dry Eng. ….1734 …. ….1735 wet ….1736 wet ….1737 …. very severe Am.1738 …. ….1739 wet England very severe Eng.1740 …. very severe Am.1741 …. ….1742 …. severe Syria1743 hot ….1744 …. ….1745 …. ….1746 …. ….1747 hot and dry severe1748 dry ….1749 very dry ….1750 very hot very severe1751 wet England severe Amer.1752 very hot Amer. ….1753 …. severe1754 …. mild Amer.1755 …. severe Europe1756 …. severe Syria1757 …. ….1758 hot ….1759 …. severe1760 …. ….1761 very dry Amer. ….1762 very dry Amer. severe1763 …. ….1764 hot Europe ….1765 hot Europe severe Europe1766 hot and dry Eur. very severe1767 …. cold1768 hot ….1769 hot ….1770 wet England ….1771 wet Am. & England cold Europe1772 hot America Am., great snow1773 …. ….1774 …. severe Europe1775 …. ….1776 hot severe Europe1777 …. ….1778 hot mild1779 hot Eng. very severe1780 …. ….1781 …. ….1782 dry Amer. ….1783 hot very severe1784 hot ….1785 dry Europe cold1786 cool cold1787 cool ….1788 rainy Amer. cold1789 cool spring, hot summer severe Eur., mild Amer.1790 …. ….1791 very hot Am. cold1792 …. ….1793 hot, dry Am. mild Amer.1794 …. severe Europe1795 Amer., hot, rainy ….1796 Autumn very Dry Am. cold Amer.1797 cool Am. severe Amer.1798 very hot} {long & severe1799 very dry Am.} {Amer. & Eur.Still more definite evidence is found in the meteorological tables of Dr. Holyoke and Dr. Hildreth, and an account, by Dr. Hildreth, of the seasons when the Ohio River was closed or obstructed by ice, found in Silliman’s Journal, new series, vol. xiii. p. 238.Thus, we have, from the tables of Dr. Holyoke, the following annual means, from 1786 to 1825, inclusive. I have arranged them in periods of five years. It will be seen that there are three peculiarities observable. First, a marked difference between the first and second periods of the decade, corresponding, generally, with the presence or absence of the spots. Second, a difference in the mean of the decades which may well be supposed to correspond with the difference in the number or size of the spots since a like difference is observable in number and size and the time when they reached their maxima and minima, in the table of Schwabe. And, third, there are occasional single cold years during the warm period and these correspond with what the tables of Dr. Webster show for both the sixteenth and seventeenth centuries. In relation to this, it should be remembered that volcanic action is a frequent and powerful disturber of the regular action of terrestrial magnetism and that the extremes, for that reason, are frequently meridional or local and alternating; and to that cause very great extremes and marked exceptions, may be due, notwithstanding the spots upon the sun may exert an influence in producing hot summers and cold winters toward the close of each decade. Thus, to select an instance to illustrate this and explain an anomaly: The coldest season during the whole period, embraced in the following tables, is that of 1812. This occurs during the decrease of spots, and the warm half of the decade. Turning to the table of volcanic action and of earthquakes, found in the Report of the British Association for 1854, we find that year was remarkable for earthquakes in the United States and South America. In December, 1811, earthquakes commenced in the valley of the Mississippi, Ohio and Arkansas, felt also at places in Tennessee, Kentucky, Missouri, Indiana, Virginia, North and South Carolina, Georgia and Florida, though not so severely east of the Alleghenies, which continued until 1813. About the same time they commenced in Caraccas, and, in March, 1812, became severe over the greater portion of the northern section of South America and in the Atlantic. No such general and continued succession of earthquakes occurred during the other periods embraced in the tables and the mean of the following five years was very low, embracing the memorable cold summer of 1816.Cold Period. Warm Period. Cold Period. Warm Period.1786 48°.53 1791 48°.963 1796 48°.678 1801 50°.4321787 47°.88 1792 48°.44 1797 48°.135 1802 50°.7941788 47°.676 1793 50°.96 1798 49°.471 1803 50°.241789 47°.68 1794 50°.768 1799 48°.291 1804 48°.3281790 46°.53 1795 50°.173 1800 49°.989 1805 50°.792Mean of period 47°.659 Mean 49°.901 Mean 48°.910 Mean 50°.117 1806 47°.982 1811 50°.76 1816 47°.113 1821 48°.151807 48°.132 1812 45°.28 1817 46°.277 1822 49°.811808 49°.485 1813 47°.702 1818 48°.009 1823 47°.581809 47°.92 1814 48°.279 1819 50°.75 1824 49°.251810 49°.001 1815 47°.607 1820 48°.70 1825 50°.99Mean 48°.505 Mean 47°.925 Mean 48°.169 Mean 49°.15The tables of Dr. Hildreth, from 1826 to 1854, inclusive, furnish, generally, evidence of a like character. There are, however, an anomaly or two which will be observed. From 1826 to 1830, the mean is high during the period when spots were at a maximum. But that maximum embraced a much less number of spots than the two succeeding ones. A contrast appears in the tables of Dr. Hildreth, during the early period, for Dr. Holyoke’s register, for 1827, puts it below the mean but Dr. Hildreth’s one of the highest of the half century. In 1835 commenced a period when the spots were much more numerous and from 1835 to 1838, inclusive, the seasons were correspondingly below the mean. From that period to 1844 a gradual and slightly irregular rise took place, excepting the year 1843, when another cold year intervened. The table of earthquakes, published by the British Association, closes with 1842 and I have not access to any others. The occurrence of such cold years, in the warm period, at intervals during the two centuries previous and in 1812 and onward and evidently owing to increased volcanic action beneath the western portion of the northern hemisphere, justifies the belief that the low temperature of 1843 was owing to the same cause. The following are the means from the tables of Dr. Hildreth:1826 54°.00 1831 50°.87 1836 50°.03 1841 52°.18 1846 53°.641827 54°.92 1832 52°.42 1837 51°.57 1842 52°.83 1847 52°.001828 55°.22 1833 54°.56 1838 50°.62 1843 50°.77 1848 52°.501829 52°.38 1834 52°.40 1839 52°.54 1844 53°.25 1849 52°.091830 54°.93 1835 50°.65 1840 52°.35 1845 52°.73 1850 51°.48Mean 54°.29 Mean 52°.18 Mean 51°.52 Mean 52°.35 Mean 52°.32The observations of Dr. Holyoke were made at Salem, Massachusetts; those of Dr. Hildreth at Marietta, Ohio.The following, in relation to the freezing of the Ohio River, is evidence of a different kind but shows the same general correspondence and particularly the mildness of the winters when there were few spots and their severity from 1836 to 1838, inclusive, when the spots were most numerous:1829.; River open all winter; some floating ice. 1830.; River closed 27th January. 1831.; Floating ice; closed 23d January; opened 20th February. 1832.; Closed in December, which was a very cold month; opened January 8 and remained open all winter. 1833.; Open all winter. 1834.; Open all winter. 1835.; Closed January 6; opened the last of the month; cold. 1836.; Closed 28th January; opened 25th February. 1837.; Closed from 8th December to 8th February. Cold year. 1838.; Closed from 13th January to 13th March. Cold year. 1839.; Closed from 6th December to 13th January. 1840.; Closed 29th December; opened 15th January. 1841.; Closed 3d January; opened 8th do. 1842.; Open all winter. 1843.; Closed 28th November; opened 5th December; open all the rest of the winter. 1844.; Open all winter. 1845.; Open all winter. 1846.; Closed 5th December; opened again a few days; closed again on the 26th. It is not stated how long it remained closed. 1847.; Open all winter. 1848.; Much floating ice but not closed; heavy rains and floods. 1849.; Floating ice in January but not closed. 1850.; Floating ice but not closed. 1851.; Open all winter; a little ice. (December in the above table, means December previous).This is more reliable as to the winter season than the tables of annual means; although the evidence they afford, making due allowance for the exceptions, is very striking.I shall return to this part of the subject again.But there is other evidence of the influence of these spots. Their connection with the irregular magnetic disturbance of the earth has been distinctly traced. Colonel Sabine, President of the British Association, in his opening address, September, 1852, after reviewing the recent discoveries in magnetism, says:; “It is not a little remarkable that this periodical magnetic variation is found to be identical in period and in epochs of maxima and minima, with the periodical variation in the frequency and magnitude of the solar spots, which M. Schwabe has established by twenty-six years of unremitting labor. From a cosmical connection of this nature, supposing it to be finally established, it would follow that the decennial period, which we measure by our magnetic instrument, is, in fact, a solar period, manifested to us, also, by the alternately increasing and decreasing frequency and magnitude of observations on the surface of the solar disc. May we not have in these phenomena the indication of a cycle, or period of secular change in the magnetism of the sun, affecting visibly his gaseous atmosphere or photosphere and sensibly modifying the magnetic influence which he exercises on the surface of our earth?”; American Journal of Science, new series, vol. xiv. p. 438.I think it may fairly be inferred, that although these spots do not occasion the “cold spells” and “hot spells,” and other transient peculiarities, they do materially affect the mean temperature of the year and exert an obvious influence when at their maxima; and there is a tendency to an increase of the heat and dryness of summer and the severity of winter, at the periods named, in our excessive climate and a well-established connection between the spots and magnetic disturbances and variations.Popular opinion has ever attributed to the moon a controlling effect upon the changes of the weather. If it be dry, a storm is expected when the moon changes; or if it be wet, dry weather. Such popular opinions are usually entitled to respect and founded in truth. But every attempt to verify this opinion, by careful observation and registration, has failed. Weather-tables and lunar phases, compared for nearly one hundred years, show four hundred and ninety-one new or full moons attended by a change of the weather and five hundred and nine without. The celebrated Olbers, after fifty years of careful observation and comparison, decided against it. So did the more celebrated Arago, at a more recent date; summing up the result of his observations by saying; “Whatever the progress of the sciences, never will observers, who are trustworthy and careful of their reputation, venture to foretell the state of the weather.” Still, the moon may influence the weather, though she may not effect changes at her syzygies or quadratures and this subject should not be too summarily dismissed. That the moon can not effect changes at the periods named seems philosophically obvious. She changes, for the whole earth, within the period of twenty-four hours; yet, how varied the state of things on different portions of its surface. The equatorial belts of trades and drought and rains, cover from fifty to sixty degrees of its surface and know nothing of lunar disturbance. The extra-tropical belt of rains and variable weather moves up in its season, uncovering 10°, or more, of latitude and admitting the trades and a six months’ drought over it, as in California, regardless of the moon. Under the zone of extra-tropical rains, even upon the eastern part of the continent of North America, “dry spells” and “wet spells” exist side by side; the focus of precipitation is now in one parallel and now in another; storms exist here and fair weather there, on the same continent at the same time; and as the moon’s rays in her northing pass round the northern hemisphere during the twenty-four hours, they, doubtless, pass from ten to thirty or more storms, of all characters and intensities, moving in opposition to her orbit; and as many larger intervening areas of fair weather, not one of which are indebted to her for their existence, or “take thought of her coming.”The storm, which originates in the tropics, pursues its curving way now N. W., then N. E. and again north, to the Arctic circle, and, perhaps, around the magnetic pole, over gulf and continent and ocean, occupying one third the time of a lunation and two changes, perhaps, in its progress, without any perceptible or conceivable influence from her. Yet every inhabitant of mother-earth, influenced by coincidences remembered and uninfluenced by exceptions forgotten, looks up within his limited horizon and devoutly expects from the agency of some phase of the moon, a change for the special benefit of his dot upon the earth’s surface. Upon how many of these countless dots is the moon at a particular phase, or relative distance from the sun, to change fair weather to foul, or foul to fair?Upon none. The storms keep on their way; the wet spells and the dry spells, the cold and the hot spells alternate in their time and though the moon turns toward them in passing, her dark face, her half face, or her full orb (the gifts of the sun, which confer no power), they do not heed her. They are originated and are continued, by a more potent agent. They are the work of an atmospheric mechanism, as ceaseless in its operation as time, as regular as the seasons, as extensive as the globe.Indeed, it seems as if it was expressly designed by the Creator that the moon should not interfere materially with this atmospheric machinery. She is the nearest orb; her influence would be controlling and continuous; would follow her monthly path from south to north and with changes too violent and intervals too long; and would interfere with the regular fundamental operation in the trade-wind region, where she is vertical. Aside from the attraction of gravitation, therefore, she seems to have been so created as to be incapable of exerting any influence. She is without an atmosphere; the rays which she reflects are polarized and without chemical or magnetic power; and, if it be true that Melloni has recently detected heat in them, by the use of a lens three feet in diameter, which could not previously be effected, its quantity is exceedingly small and incapable of influence. Doubtless, the attraction of her mass is felt upon the earth, as the tides attest; and upon the atmosphere as well as the ocean. But the atmosphere is comparatively attenuated and exceedingly so at its upper surface. Her attraction, therefore, although felt, is not influential. She seemed, to Dr. Howard, to produce in her northing and southing, a lateral tide which the barometer disclosed, but owing to the attenuated character of the atmosphere, neither the sun nor moon create an easterly and westerly tide, that is observable, except with the most delicate instruments. Sabine is believed to have detected such a tide by the barometer, at St. Helena, of one four thousandth of an inch. But even this infinitesimal influence may prove an error upon further investigation. There is a diurnal variation of the barometer but it is not the result of her attraction, for it is not later each day as are the tides, exists in the deepest mines as well as upon the surface and is demonstrably connected with the group of diurnal changes produced by the action of the sun-light and heat upon the earth’s magnetism.Can the lateral tide, if there be one, affect the weather?for in the present state of science it seems entirely certain that the moon can exert an influence in no other way.If the received idea of many, perhaps most, meteorologists, on which all wheel barometers are constructed, that a high barometer necessarily produces fair weather and a low one foul, were true, she certainly might do so. But that idea can not be sustained and there is no known certain influence exerted by the moon upon the weather, in relation to which we have any reliable practical data.Humboldt appears to have adopted the impression of Sir W. Herschell, that the moon aids in the dispersion of the clouds. (Cosmos, vol. iv. p. 502.) But the tendency to such dispersion is always rapid during the latter part of the day and evening, when there is no storm approaching and the full moon renders their dissolution visible and attracts attention to them. The Greenwich observations, also, carefully examined by Professor Loomis, fail to confirm the impression of Herschell and Humboldt and those eminent philosophers are doubtless in this mistaken.From this general and somewhat desultory view of the general facts, which bear analogically upon the question, no decisive inference can be drawn in relation to the seat of the primary influence which produces the atmospheric changes. The preponderance is in favour of the magnetic, or magneto-electric, action of the earth. We must come back to our own country and grapple with the question at home.
I say that because when I've wanted to publish a very long comment (a script, for instance), they've cut it off badly..
The following diagram is a section of the New Haven tornado, from Professor Olmstead’s map accompanying his article in the “American Journal of Science and Art,” vol. 37. p. 340.The manner in which the main currents flow is shown by their early and unresisted effect in a cornfield, as represented by the dotted lines. The direction in which the fragments of buildings were carried by the greater power of the southerly currents is shown also. And so is this irregular action, where a part of the southerly current broke through the northerly one and prostrated two or three trees backward on the north side of the axis.5th. This cloud and its spout, move generally with the course of the counter-trade in the locality; i. e., from some point between S. W. and W., to the eastward but occasionally a little south of east, deflected by the magnetic wave beneath the belt of showers.6th. Several exceedingly instructive particulars have been observed and recorded.a. No wind is felt outside of the track, as those assert who have stood very near it and its effects show.b. The track is often as distinctly marked, where it passed through a wood, as if the grubbers had been there with their axes to open a path for a rail-road. The branches of the trees, projecting within its limits, are found twisted and broken off, or stripped of their leaves, while not a leaf is disturbed at the distance of a foot or two on the opposite side of the tree and outside of the track.c. As the spout passes over water, the latter seems to boil up and rise to meet it and flow up its trunk in a continued stream.d. As it passes over the land and over buildings, fences and other movable things, they appear to shoot up, instantaneously, as it were, into the air and into fragments. If buildings are not destroyed or removed, the doors may be burst open on the leeward side and gable ends snatched out and roofs taken off on the same side, while that portion of the building which is to the windward remains unaffected.e. Articles of clothing and other light articles, have been carried out of buildings through open doors, or chimneys, or holes made in the roofs and to a great distance, without any opening being made for the air to blow in.f. If there be a discharge of electricity up the spout from the earth, like that of lightning, the intense action ceases for a time or entirely.g. Vegetation in the track is often scorched and killed and so of the leaves on one side of a tree, which is within the track, while those on the other side and without the track remain unaffected. (Espy’s Philosophy of Storms, 359, cited from Peltier.)h. The active agent whatever it is, has been known to seize hold of a chain attached to a plow and draw the plow about, turning the stiff sod for a considerable distance. (See Loomis on the tornado at Stow, Ohio, American Journal of Science, vol. xxxiii. p. 368.)i. In passing over ponds, the spout has taken up all the water and fish and scattered them in every direction and to a great distance.j. The barometer falls very little during the passage of the spout. (See the Natchez hurricane of 1827, Espy page 337.) Not more than it frequently does during gentle showers.k. Persons have been taken up, carried some distance and if not projected against some object in the way, or some object against them, have usually been set down gently and uninjured.l. Buildings which stood upon posts, with a free passage for the air under them, although in the path of the tornado, escaped undisturbed. (Olmstead’s account of the New Haven tornado, American Journal of Science, vol. xxxvii. p 340.)m. A chisel taken from a chest of tools and stuck fast in the wall of the house. (Ibid.)n. Fowls have had all their feathers stripped from them in an instant and run about naked but uninjured.[5]o. Articles of furniture, etc., have been found torn in pieces by antagonistic forces.p. Frames taken from looking-glasses without breaking the glass. Nails drawn from the roofs of houses without disturbing the tiles.q. Hinges taken from doors; mud taken from the bed of a stream (the water being first removed) and let down on a house covering it completely; a farmer taken up from his wagon and carried thirty rods, his horses carried an equal distance in another direction, the harness stripped from them and the wagon carried off also, one wheel not found at all. (American Journal of Science, vol. xxxvii. p. 93.)Pieces of timber, boards and clapboard, driven into the side of a hill, as no force of powder could drive them, etc., etc.Now to my mind, these circumstances indicate clearly, that it is not wind, i. e., mere currents of air, which produces the effect but that a continuous current or stream of electricity from the earth to the cloud exists and carries with it from near the earth, such articles as are movable: That this stream collects from the northerly and southerly side upon the magnetic meridian, in two currents with polarity, which meet in their passage up at the centre; curving toward the centre in the posterior part as the spout moves on, when acting in a normal manner and making the “law of curvature” observed: That no conceivable movement of the air alone in such limited spaces could produce such effects; or if so, that no agent but electricity could so move the air: That the air in a building could not shoot the roof upward and into fragments; much less could the air in a cellar by any conceivable force, be made to elevate or shoot up the entire house and its inmates and contents; effects so totally unlike what takes place in gales, hurricanes and typhoons: That elastic free air never did nor could take hold of the plow chain and plow up the ground; or scorch and kill the vegetation; or twist the limbs from one side of a tree, while the most delicate leaves on the other and within two or three feet, remained unaffected and undisturbed; or pick the chickens: That even if the expansion of the air could produce these effects; if a sudden vacuum were produced; nothing but currents of electricity could produce the sudden vacuum, by removing the air above.It is well settled that atmospheric electricity can and does flow in currents with light, by experiments in relation to the brush discharge, etc. That it may do so without light or disruptive discharge and in a stream, or as it is termed, by convection, with the force and effect seen in the tornado, is perfectly consistent with what we know of it; and it is, I think clearly evinced that such is the character of the phenomena, by the fact that a sudden powerful disruptive discharge, with light, up the spout, produces an instantaneous partial or total suspension of its action; to be renewed as the cloud passes over another and more highly charged portion of the earth’s surface. Peltier gives instances where the spout has been entirely and instantaneously destroyed by such a sudden and powerful discharge of electricity; marking the spot where it was so destroyed by a large hole in the earth, from which the discharge issued. And in fact these tornadoes are often steadily luminous, and so much so, when they occur in the night, as to enable persons to read without difficulty.The lateral inward and upward currents, are accompanied, after they meet and unite, or seem to unite, by gyratory or circular ones. How are they produced?This question can only be answered by analogy. No permanent impressions are left by the circular currents, except to a limited extent and in occasional instances; and observation of them has been and must necessarily be limited and uncertain. I have witnessed one or two on a moderate scale; but owing to the suddenness of their passage and the confusion of the objects taken up, it was difficult to determine what the circular currents were. When the southerly current is much the strongest, it appears sometimes to cross the axis and curve round the northerly one. Perhaps this may be all the curving that really takes place, except at the posterior part of the axis, for evidence of a curving on the south of the axis is rarely, if ever seen.Assuming, however, that the main currents unite and form one from the earth to the cloud, induced circular currents would be in perfect keeping with the known laws of electricity. Such currents and with magnetic properties, are always induced by powerful currents of voltaic electricity passing through wires. And doubtless in all cases powerful currents of electricity induce attendant circular currents. This may account for the external gyration of the spout.Or it may be that the two lateral currents of air which attend the currents of electricity, do not unite; having opposite polarity but pass by and around each other, in connection with the circular magnetic currents. Future observation and perhaps experimental research will determine this. But it may not be accomplished by the present generation; for the belief that tornadoes are mere whirlwinds, produced by the action of the sun in heating the land, is adhered to, notwithstanding they cross the intense magnetic area of Ohio in mid-winter and seems to be ineradicable.The proportions of different winds vary in different localities. For the benefit of those who are curious, I copy a table from an able compilation by Professor Coffin, published by the Smithsonian Institute, showing the proportion of the winds at New Haven (the station nearest to me). It will be noticed that during the year the N. W. winds blow the greatest number of days; the S. W. next; the N. E. and S. E. less than either and about equal. It may be observed that the two latter bear about the same proportion to the whole, that our number of cloudy and stormy days, averaging about ninety, bear to the whole number of days in the year.Course. 1804. 1811. 1812. 1813. Total.N. 143 105 90 111 449N. E. 99 207 138 138 582E. 33 18 22 23 96S. E. 131 108 135 110 484S. 58 69 113 80 320S. W. 224 255 153 261 893W. 81 69 102 57 309N. W. 329 264 345 315 1253This work of Mr. Coffin has been brought to my notice since the foregoing pages were written. The facts embodied in it will be found to comport with what I have observed and stated. In relation to the proportionate number of days in the year during which the wind blows from the different points of the compass at the several stations it is very full and able.But it has cardinal defects. It does not show the main currents of the atmosphere. It treats the surface-winds, which are incidental, as principals. The direction of the main currents is indeed shown frequently by the mean course of the surface winds but not uniformly or intelligibly. Nor does it distinguish between the fair weather and storm winds; nor always between the trade winds during their northern transit and the variable winds north of the trade-wind region. Hence, the deductions derived from it disclose no general system and sustain no theory, although many very important facts appear. Some of these, Professor Coffin found it difficult to reconcile with received theories, or satisfactorily explain. For instance, he found the prevailing winds of the United States, in Louisiana and Texas, S. and S. E.; in western Arkansas and Missouri, southerly and in Iowa and Wisconsin, S. W., forming a curve and evidently connected together.Thus, alluding to the winds west of the Mississippi and between the parallels of 36° and 60°, he says:“On the American continent, west of the Mississippi, there appears to be more diversity in the mean direction of the wind, yet here it is westerly at sixteen stations out of twenty, from which observations have been obtained. The most peculiar feature in this region, is the line of southerly winds on the western borders of Arkansas and Missouri. It seems to form a connecting link between the winds of this zone and the south-easterly ones that we find south of it; and, in some degree, to favour an idea that has been advanced, that there is a vast eddy, extending from the western shore of the Gulf of Mexico, to the eastern shore of the Atlantic; that the easterly trade-winds of the Atlantic Ocean, when they strike the American continent, veer northwards and then N. E. and thus recross the Atlantic and follow down the coast of Portugal and Africa, till they complete the circuit.”This mean prevalence of the curving winds indicates the course of the western portion of the concentrated counter-trade, of which we have so fully spoken and to which that portion owes its rains and fertility. Doubtless the curve would have been traced somewhat further west, if observations had been obtained from more westerly stations.The idea of an eddy, to which Professor Coffin alludes, is of course unsound; that of a counter-trade, most fully confirmed; the curve corresponding with that of the regular rains and fertility as they are known to exist.Professor Coffin is a believer in the generally-received theory of rarefaction, as the cause of all winds. His work is published by the Smithsonian Institution and the theory is, so far forth, nationalized. But he found it very difficult to reconcile all the facts he obtained, with the theory, and, possessing a truth-loving mind, he frankly admits it. Alluding to the prevalence of N. E. winds off the coast of Africa in the summer months, as shown by certain numbered wind-roses, he says:“Nos. 81, 83, 86 and 91, have caused me much perplexity. The arrows for the warmer months evidently indicate a point of rarefaction situated to the south or south-west and yet all the observations from which they were computed were taken within a few hundred miles of the African coast and desert of Sahara; a region, the annual range of whose temperature must be exceedingly great. The only way in which I can account for a fact so astonishing, is, by supposing the deflecting forces at these numbers to be secondary to the influence which we see so strongly marked in Nos. 88, 89 and 90. Let us, then, first devote our attention to these.”(We have not space for the map of Professor Coffin, nor is it necessary to insert it. The numbers 81, 83, 86 and 91, refer to respective portions of the Atlantic, west of Africa, North of the Cape de Verdes, of 5° of latitude each, where the N. E. trades are drawing off from the coast. The Nos. 88, 89 and 90 refer to like portions below the Cape de Verde, where the S. W. monsoons are found under the rainy belt; and the explanation of the distinguished author is an attempt to account for the blowing of the trades from Sahara, by supposing them connected with the monsoons further south, which seem to blow toward it.)“The intense heat of the Great Desert rarefies the air exceedingly from June to October, inclusive and hence the arrows of unparalleled length (Plate XII.),” (showing the monsoon winds below the Cape de Verdes,) “pointing toward it during those months, the longest being longer than that which represents the most uniform of the trade-winds, in the ratio of 104 to 89. The influence of this rarefaction is sufficient to curve the powerful current of the trade-winds in the manner exhibited on Plate VII. Nos. 89 and 90 and to produce the not less remarkable change in No. 88, holding the current back and retarding it, so that its progressive motion in the three months of July, August and September united, hardly exceeds that during any one of the colder months of the year. But while this is so, the trades on the western side of the Atlantic are pursuing nearly their regular track, being but slightly affected by these influences. As a consequence, the latter must leave, as it were, a partial vacuum behind them, which is filled by air flowing in from the north-east and south-east. This will account for the seeming anomaly of having a somewhat strong deflecting force directed toward mid-ocean, in the hottest part of the year, as in the numbers above referred to. And yet it may be very naturally asked, Why does not the air from these parts supply the Great Desert directly, instead of taking a circuitous route to supply the region that supplies it?A question which, I confess, it seems difficult to answer.”(The italicization in the foregoing extract is mine).Here the worthy professor finds a fact inconsistent with the theory of rarefaction; viz.: that the winds blow off shore and toward mid-ocean, opposite Sahara and he is “perplexed and astonished.” The theory, however, must be maintained and one of those modifying hypotheses which have made meteorology such a complicated piece of patch-work, must be invented; some “deflecting forces” found. There is the Great Desert, bordering upon the ocean, north of the Cape de Verde Islands, for a distance of six hundred miles, widening as it extends inland, whose temperature, as he says, “must be exceedingly great;” and doubtless is so and yet the air, instead of blowing in upon it in a hurricane, is actually drawing off from it and blowing towards the S. W., where the water and air do not rise above 84°. Well may he be “perplexed and astonished.”Turning south, however, to the distance of five hundred miles or more, he finds the S. W. monsoon winds, which in those months blow under the belt of rains, toward the land, in the direction of but at a great distance from, Sahara. It is an easy matter to suppose that they reach the Great Desert and supply its vortex of rarefaction, inasmuch as they blow in a direction toward it and distance is no impediment to supposition.Then it is necessary to suppose that the S. E. and N. E. trades, at the south-west, draw so strongly to the westward as to create a partial vacuum to the S. W. of Sahara, which is filled by the winds which draw off shore and then we have the supply brought from the distance of five hundred miles or more, by an ascending vortex, which creates a vacuum and the air near the vortex taken away in another direction by a partial vacuum; and so an ascending vortex, which creates a vacuum is supplied from a distance and a partial vacuum at a distance is supplied by the air near the perfect vacuum. Such an idea of a supply by a circuitous route and secondary influence, is not very philosophical, to say the least and Professor Coffin feels it; and to the question, Why is it so?which, he says, may very naturally be asked, he confesses there is no answer. And there would be none, even if his suppositions were based upon facts. But other questions might be asked equally difficult to be answered, viz.:1st. Is there any rarefaction which can draw the trades to the west and in that particular locality, in opposition to the supposed vortex of Sahara, by creating a partial vacuum?2d. Are they in fact so drawn?3d. Do the S. W. winds, south of the Cape de Verdes and under the rainy belt, which in the summer months extend up to these islands, reach the desert at all?These are pertinent questions and every one of them must be answered in the negative. The hypothesis is without foundation and Professor’s Coffin’s perplexity and astonishment must remain, until he abandons the theory of rarefaction entirely. The winds which so perplex him are nothing but the regular N. E. trades, made to originate on the coast and continent of Africa, in summer, by the northern transit of the whole machinery. They not only draw off from the desert coast but they blow over the desert itself on to the ocean and into the rainy belt upon the land, as we have already seen and the supposed vortex of rarefaction does not exist.That the monsoons do not reach the desert is demonstrated by the tables of Professor Coffin and to set it at rest we will make the necessary extracts. Commencing with the region from the equator to 5° N. and from 10° to 55° W. longitude, we have the observed winds in proportion, as follows, for July and August; the south-east trades prevailing, inasmuch as the belt of rains is at this season situated further north.Latitude 0° To 5°, Longitude From Greenwich 10° To 55°.Course. July. August. Course. July. August.North. 0 0 S. S. W. 54 111N. N. E. 8 2 S. W. 1 29N. E. 6 2 W. S. W. 6 19E. N. E. 27 16 West. 2 9East. 31 20 W. N. W. 1 6E. S. E. 120 96 N. W. 1 0S. E. 216 276 N. N. W. 0 2S. S. E. 218 443 Calm. 8 4South. 69 279 Total 768 1,314Here, it is evident that the S. E. trades are the prevailing winds but their course is variable.Ascending to the region between 5° and 10° north latitude and 10° to 55° west longitude, the northern part of which at this season is covered by the rainy belt; we find the monsoon, the S., S. S. W. and S. W. winds, the prevailing ones in August, although the winds are variable, as usual under the rainy belt.Course. July. August. Course. July. August.North. 19 6 S. S. W. 188 368N. N. E. 26 11 S. W. 63 94N. E. 194 32 W. S. W. 73 93E. N. E. 30 16 West. 33 48East. 45 29 W. N. W. 30 18E. S. E. 36 40 N. W. 21 9S. E. 93 53 N. N. W. 17 13S. S. E. 225 307 Calm. 109 74South. 239 514 Total 1,351 1,725Ascending to the region of 10° to 15° north latitude and 15° to 45° west longitude, we find the winds exceedingly variable and the monsoons diminished remarkably. If Professor Coffin’s theory was correct, they should increase as they approach the desert; but they in fact, diminish and the N. E. trades are found at the north portion.Course. July. August. Course. July. August.North. 17 55 S. S. W. 30 71N. N. E. 64 74 S. W. 33 63N. E. 155 149 W. S. W. 19 43E. N. E. 91 71 West. 12 25East. 83 60 W. N. W. 17 21E. S. E. 25 26 N. W. 13 24S. E. 17 26 N. N. W. 24 56S. S. E. 13 33 Calm. 62 78South. 9 44 Total 684 919Ascending to the region between 15° and 20° north latitude and 15° to 45° west longitude, we get north of the belt of rains and lose the monsoons entirely although still below the desert; and find the regular N. E. trades, with less variable winds than are found in almost any other part of the ocean.Course. July. August. Course. July. August.North. 39 20 S. S. W. 0 5N. N. E. 210 185 S. W. 0 5N. E. 112 87 W. S. W. 8 3E. N. E. 114 104 West. 0 1East. 20 36 W. N. W. 0 4E. S. E. 21 17 N. W. 3 4S. E. 0 2 N. N. W. 3 31S. S. E. 2 11 Calm. 20 8South. 5 1 Total 557 526Ascending still further to the region between 20° and 25° north latitude and 15° and 45° west longitude, which borders, in part, on the S. W. corner of the desert and we have not, during the month of August, a single wind between S. S. E. and W. N. W., which blows in upon the land; and only twelve instances out of three hundred and ninety-four in this hottest month in the year and on the southern portion of the desert, when the wind blows on shore from any quarter. This is demonstration. The monsoon winds are confined to the rainy belt; they do not reach the desert, nor does the desert attract the winds from the ocean, or reverse, hold back, or disturb the trades.Course. July. August. Course. July. August.North. 25 20 S. S. W. 3 0N. N. E. 210 153 S. W. 2 0N. E. 129 77 W. S. W. 13 0E. N. E. 110 86 West. 0 0East. 8 20 W. N. W. 0 3E. S. E. 4 11 N. W. 2 1S. E. 0 3 N. N. W. 5 8S. S. E. 1 7 Calm. 2 5South. 1 0 Total 515 394Ascending once more, to the region between the degrees of 25 and 30, north latitude and 15 and 45, west longitude, we find it bounded east entirely on the centre of the desert. Now here, certainly, there must be evidence of the truth of the rarefaction theory, if any where on the face of the earth. Yet here, in July and August, we find the trades as regular as any where and not more variable winds than are found in the trades toward their northern limits everywhere and in August, only forty out of four hundred and twenty-nine winds, blowing directly or indirectly on shore.Course. July. August. Course. July. August.North. 32 19 S. S. W. 9 6N. N. E. 155 125 S. W. 3 9N. E. 144 35 W. S. W. 13 14E. N. E. 140 89 West. 12 3East. 48 57 W. N. W. 7 7E. S. E. 31 23 N. W. 11 1S. E. 8 7 N. N. W. 36 6S. S. E. 8 12 Calm. 18 12South. 5 4 Total 680 429It would seem to be impossible for any man to believe in the theory of rarefaction, after an examination of these tables.
Professor Coffin discovers other anomalies, for which he finds it difficult to account. Among these are the northerly tendency, in the afternoon, of the winds in Ohio, south of Lake Erie; the winds of south-western Asia, which, he says, “Are so irregular as to defy all attempts to reduce them to system;” particularizing the N. W. at Jerusalem, the westerly at Bagdad, the N. E. at Constantinople, the northerly at Trebizond, etc., etc. Jerusalem has the Mediterranean at the N. W., Bagdad has it at the west, Constantinople has the Black Sea at the N. E., Trebizond N. N. W. and N. E. and the counter-trade, as it passes over them, draws its storm-surface wind or sea-breeze, from the quarter where evaporation is greatest and the atmosphere is most susceptible of electrical inductive influence. Precisely as it draws from the ocean and the eastward, east of the Alleghenies, from the lake region, west of the lakes and from the northward, south of the lakes and from the westward, east of them.This law of attraction will explain, too, the mean prevalence of easterly winds north of the parallel of 60°, at the stations named in his work. Great Bear Lake, Great Slave Lake and Fort Enterprise, lie east of the Rocky Mountain range which interposes between them and the Pacific and have Hudson’s Bay and other large bodies of water on the east and north. Hence, easterly winds prevail at these places. At Norway House, on Nelson’s River, near the north end of Lake Winnipeg, a large body of water, which stretches off to the south, we find the south wind the prevalent one, especially in December, when the northern and north-eastern waters are frozen up and the N. E. largely present at all seasons of the year.At New Hernhut, in winter, when Davis’ Straits are covered with floes, the prevailing wind is east, drawn from the warm, open sea east of Greenland, where the Gulf Stream is evaporating. But in June and July, when evaporation is going on over Davis’ Straits and Baffin’s Bay, the prevailing winds are west and south and the east winds fall off.Other stations are equally instructive but I must forbear.In relation, however, to the easterly zone of wind, of which Professor Coffin speaks, it should be added that the counter-trade, south of the magnetic pole, in high latitudes, pursues an easterly course, is near the earth and attracts an opposite wind as it does on the east and north of the pole, in localities where the surface atmosphere is not peculiarly susceptible to its influence, and, therefore, the winds are mainly opposite to its course. Thus, at Melville Island, they are almost all westerly and north-westerly, for there the remnant of the counter-trade is passing west around the magnetic pole. These westerly and north-westerly winds are very light and like the gentle easterly breeze which sets toward the cumulus clouds and summer showers.Since most of this work was written, I have procured and read with great pleasure, Lieutenant Maury’s “Geography of the Sea.” It is a work of great interest and should be in the hands of every one. The extent of ground covered, however, made it necessary for Lieutenant Maury to introduce much matter not derived from his own investigations. In doing this, he has taken received opinions and has thereby introduced much heresy. The view he adopts in relation to the monsoons, although the popular one with philosophers, is of that character. He says (page 222):“Monsoons are, for the most part, formed of trade-winds. When a trade-wind is turned back, or diverted, by over-heated districts, from its regular course at stated seasons of the year, it is regarded as a monsoon. Thus, the African monsoons of the Atlantic, the monsoons of the Gulf of Mexico and the Central American monsoons of the Pacific, are, for the most part, formed of the north-east trade-winds, which are turned back to restore the equilibrium which the over-heated plains of Africa, Utah, Texas and New Mexico have disturbed. When the monsoons prevail for five months at a time; for it takes about a month for them to change and become settled; then both they and the trade-winds, of which they are formed, are called monsoons.”Again (§ 476-7):“The agents which produce monsoons reside on the land. These winds are caused by the rarefaction of the air over large districts of country situated on the polar edge, or near the polar edge, of the trade-winds. Thus, the monsoons of the Indian Ocean are caused by the intense heat which the rays of a cloudless sun produce, during the summer time, upon the Desert of Cobi and the burning plains of Central Asia. When the sun is north of the equator, the force of his rays, beating down upon these wide and thirsty plains, is such as to cause the vast superincumbent body of air to expand and ascend. There is, consequently, a rush of air, especially from toward the equator, to restore the equilibrium; and, in this case, the force which tends to draw the north-east trade-winds back becomes greater than the force which is acting to propel them forward. Consequently, they obey the stronger power, turn back and become the famous south-west monsoons of the Indian Ocean, which blow from May to September inclusive.“Of course, the vast plains of Asia are not brought up to monsoon heat per saltum, or in a day. They require time both to be heated up to this point and to be cooled down again. Hence, there is a conflict for a few weeks about the change of the monsoon, when neither the trade wind nor the monsoon force has fairly lost or gained the ascendency. This debatable period amounts to about a month at each change. So that the monsoons of the Indian Ocean prevail really for about five months each way, viz.: from May to September, from the south-west, in obedience to the influence of the over-heated plains and from November to March inclusive from the north-east, in obedience to the trade-wind force.”What the “trade-wind force” is, Lieutenant Maury tells us in another paragraph, viz.: “Calorific action of the sun and diurnal rotation of the earth”; the received calorific theory. I have already shown, I think, conclusively, that there is no expansion and ascent in the supposed region of calms, which induces, or can induce, the trades; and that, in point of fact, the air on the land is cooler under the belt of rains. But as Lieutenant Maury, whose reputation is national, adopts the theory, I shall be pardoned for copying the following table, showing the difference of temperature at two cities of India, before, after and while the belt of inter-tropical rains is over them. It will be seen that the temperature is actually less when the belt is there, viz., in July and August, than in April and May. This should be conclusive upon that point.Months. Anjarakandy. Calcutta.Rain. Temp. Rain. Temp. M.M. M.M. January, 2,26 26°,5 0,0 18°,4February, 2,26 27°,7 67,68 21°,5March, 6,77 28°,4 24,82 25°,6April, 29,33 29°,8 130,84 28°,5May, 175,96 28°,6 16,24 29°,7June, 794,05 26°,6 575,24 29°,3July, 807,59 25°,8 338,38 28,°1August, 572,98 26°,0 311,31 28,°3September, 311,31 26°,4 254,91 28,°0October, 157,91 26°,8 42,86 27°,2November, 65,42 26°,9 20,30 23°,0December, 29,33 26°,5 0,0 19°,2Year, 2955,14 27°,2 1928,74 26°,4Anjarakandy is on the Malabar coast, between 12° and 13° north latitude. Calcutta in an angle of the Bay of Bengal, at 22° 30′ north latitude. The former is in and near the focus of the monsoons and has a temperature in July (when 18 inches of rain fall), about as low as in December.In the foregoing table from Kaemptz, the rain is in millimetres, about twenty-five of which make an inch and the temperature is centigrade, which may be raised to Fahrenheit by adding four fifths of the quantity and also 32°; thus, if the height of the centigrade thermometer be 25°, add to this four fifths of 25°, which is 20° and also 32°, the result is 77°. Twenty-five centigrade is therefore equal to seventy-seven Fahrenheit.Lieutenant Maury is not and should not be a theorist. He occupies the position, in some sort, of a national investigator, and, of course, of national instructor. Opinions which emanate from him, or which are endorsed by him, should be accurate. Sooner or later that which he has adopted in relation to the monsoons and some others, must be abandoned. In addition to what has already been said, I wish to call his and the reader’s attention, to several other facts and considerations in relation to the monsoons and particularly those of India.1st. The deserts of Cobi and Bucharia, which constitute the “burning plains” of Central Asia, north-east of the Indian Ocean, lie between 38° and 45° of north latitude and under the zone of extra-tropical rains. They are not wholly rainless. They partake of that saline character which affects so much of Asia and the western part of this continent. South of them, running nearly east and west, are the lofty ranges of the Himmalaya and Kuenlun Mountains and the table lands of Thibet. To their saline character, in part but mainly to the interposition of these mountain ranges, depriving the counter-trade of moisture, they owe their comparative sterility. If bountifully supplied with rains, this salt would doubtless ere this have been washed to the ocean, as it has been from other countries, once as salt as they. But they have some rain and more or less vegetation and are not intensely hot. They lie too far north and are too elevated. Their temperature is not materially different from that of the western and comparatively desert portions of our own country and they are utterly incapable of creating a monsoon at the Indian Ocean and especially from the long line of Malabar coast, where the south-west monsoons are found in most strength. The sterile portions of Utah, New Mexico, and Texas are alike incapable of such effect upon the atmosphere of Central America and Mexico. These monsoons commence in May and prevail until October and the temperature of the air where they blow ranges with considerable regularity between 76° at night and 84° at mid-day, on the Malabar coast and a trifle lower in Central America.At Fort Fillmore, El Paso, New Mexico, in latitude 32°03, the mean temperature forMay is 68°June " 78°, 5′July " 80°, 1′August " 83°, 8′September " 77°, 9′And for the whole period, 77°, 1′At Santa Fé, New Mexico, the mean forMay is 66°, 9′June " 72°, 5′July " 75°, 3′August " 72°, 9′September " 62°, 3′And for the whole period, 69°, 3′Mean of the two united, 73°, 2′The mean of Western Texas is about 2° higher than at Fort Fillmore and of Utah not materially different; and the mean of Central Asia between 38° and 45° does not materially vary from them.Now, it is perfectly evident that during May and September the temperature of Central Asia is far below that of the Indian Ocean and India and never materially exceeds it. Central Asia is hot, “burning,” if you please, compared with more elevated, fertile, or better watered territory in the same latitude and so it has been characterized; but not so, compared with the Indian Ocean, or India, where the sun is vertical. During the greater part of the time, therefore, that the monsoons are in full blast, Utah, Texas and New Mexico and Cobi and the burning plains of Asia, are from 5° to 10° colder than the temperature of the place where the monsoons are blowing. Would not such a fact be perfectly conclusive in any other science except theory-swathed meteorology?2d. The theory assumes that the heated air has an ascensive force, which causes it to rise and create a vacuum and this vacuum, by its suction, draws in the adjoining air, which immediately ascends. The adjoining air, drawn away from its locality, leaves a vacuum and that is filled by another rush from the S. W. and so on, till the Indian Ocean is reached and the monsoons are accounted for.Now, look at the difficulties:The highest temperature that can be assumed for the air over Cobi, at any time, without disregarding facts and analogy, is 100°. What is the ascensive power of an area of atmosphere of 100°?For this we have no problem or formula, although problems and formulas abound in the science. Professor Espy relied on heated air only to give the storm a start. His main reliance was on the latent heat supposed to be given out during condensation, for his ascensive storm power. But over these “burning plains” there is, according to the theory, no storm or cloud, or condensation on which that supposed reliance for expansion can be placed. What, then, is the ascension force of air at 100°?We ought to know, for we sometimes have it as high, or within two[Pg 169] or three degrees as high, in all the eastern and middle States.The monsoons blow at from twenty to twenty-five miles an hour and sometimes more. Is that the ascensive force of air at 100°?At 25 miles an hour it would be 2,200 feet; at 20 miles, 1,760 feet; and at 10 miles, 880 feet per minute.Does any man believe that either current exists?Why, then, do we not have our hats taken off, or light objects carried up, or have a monsoon, or, at least, have the clouds running up, when we have such elevated temperatures. Nothing of the kind occurs with us. Our hottest days are comparatively still days; and I have seen the cumulus sailing gently to the east, horizontally, when the air was at 98°. Why should we be exempt?Is not our air the same and our heat the same?Again, suppose we grant that the ascensive force is equal to 20 or even 10 miles an hour, will not the adjoining air hold back somewhat to avoid leaving behind an entire vacuum?or, will it all voluntarily rush in and leave a new complete vacuum?and, if so, why the preference of vacuums by the air and when, where and why, should the successive vacuums stop?Nay, would not gravity fill the second vacuum from above, rather than from the south-west side?and will not the air incline to rush in, to some or all these successive vacuums, from some other side than south-west?or, have these deserts the power of selecting the quarter from which their vacuum shall be filled and of delegating it to succeeding vacuums? Would it not incline to rush in from the east and west where there are no elevations, rather than from the S. W. and over the Kuenlun Mountains, the intervening ridges and valleys of Thibet, the lofty Himmalayas, the extent of India and the Ghaut Mountains, from three to four thousand feet high, on its eastern coast?Would it not, at least, leak in a little and lessen the force with which the vacuums would draw from the far-off Indian Ocean, so that the monsoon could not blow with equal force?or, if Cobi and its fellow deserts must and can draw from an ocean, why not from the head of the Arabian Sea, or Bay of Bengal, or the China Sea, which are nearer, or from the Japan Sea, which is still nearer, or the Yellow Sea, which is close by?Why draw only from under the central belt of rains?Nay, what shall be done with Professor Dove?In a recent article, republished in the American Journal of Science and Art, for January, 1855, he says: “A greatly diminished atmospheric pressure taking place in summer over the whole continent of Asia must produce an influx from all surrounding parts; and thus we have west winds in Europe, north winds in the Icy Sea, east winds on the east coast of Asia and south winds in India. The monsoon itself becomes, as we see, in this point of view, only a secondary phenomena.” This looks very like antagonism. Who shall we believe?Again, suppose you get one atmosphere from the whole area, raised up by the supposed ascensive force and at the rate of twenty-five, twenty, or even ten miles an hour and a new volume drawn in from the south-west and over the mountains: will it not take a little time for that to heat up?Does it heat so fast as to keep up the ascensive force without intermission, at twenty-five, or twenty, or ten miles the hour?What says Mr. Ericsson to this?Can he not arrange with a moderate lens, to move his engine with the rays of the summer sun?Nay, Lieutenant Maury says they can not heat up “per saltum, or in a day.” But according to a reasonable calculation, they must heat up the air from 80°, or less, to 100°, at the rate of 2,000 feet per minute. Heating 2,000 feet in depth, in the proportion of 20° per minute, night and day, for five months, is “per saltum” in a minute and 1,440 “saltums” per day!And further still, the Indian Ocean, from which the monsoons are drawn to Cobi and Central Asia to the N. E., is during those months covered by the belt of calms and rains, as heretofore stated; and the S. E. trades blowing into it are attributed to the suction created by the ascent of heated air there. So, then, the monsoons are blowing away from under the rainy belt, from 500 to 1000 miles, to Cobi and the burning plains of Asia, while the ascensive force of that belt is such as to draw the S. E. trades toward the very spot, a distance of 1,200 or 1,500 miles, at 20 miles an hour! What must the ascensive force over Cobi, etc., be, if, as a “stronger power,” it can overcome an ascensive force over the Indian Ocean sufficient to draw the S. E. trades 1,500 miles, at 20 miles an hour; and, in addition to the force necessary to resist this central suction, not only stop or hold back the N. E. trade but reverse it and draw it back, at 20 miles an hour, as a monsoon?Must it not be, at least, double that of the belt of calms, or the “great region of expansion,” as Professor Dove calls it?Now, I am irresistibly tempted to ask whether a meteorological theory can be too absurd for credence and whether it would not be as well to endow the deserts with ribs and lungs and a proboscis long enough to reach the Indian Ocean and the necessary power of inspiration and expiration?Such a theory would avoid all difficulties, conflict with no more analogies, and, in my judgement, be as much entitled to credit as the one to which meteorologists adhere.3d. North of the Malabar coast, in the north-west of India, lies an extensive desert. West of that is Baluchistan, with its rainless deserts. Further west are the rainless deserts of Arabia and these three, including the Persian deserts further north, cover as much surface as the deserts of Cobi and Bucharia; have the sun vertical in part and nearly so over the entire surface; are more intensely hot and lie within one third of the distance which intervenes between that desert and the Indian Ocean off the Malabar coast, with an open sea and no mountains between. Now, look at it. The north-west desert of India and the rainless deserts of Baluchistan and Arabia reverse no trade and have no monsoon, although the Arabian Sea heads right up among them. They do not attract one from the Indian Ocean off the Malabar coast, although not more than one third of the distance off and without such mountains and table lands intervening as separate that coast from Cobi. It is said by Lieutenant Maury that the monsoons, “obey the stronger force.” But which is the stronger force?Cobi, not wholly rainless, lying north of 35°, under the zone of extra-tropical rains, with India and the Ghauts, the Himmalaya Mountains, the table lands of Thibet and the Kuenlun Mountains between?or the deserts of India, Baluchistan and Arabia, wholly rainless and intensely hot, near by and in open view. There can be but one answer to this question. Nothing in the way of desert barrenness, or elevated temperature, unless it be those of the Sahara, can exceed the deserts about the head of the Arabian Sea and Persian Gulf. Certainly those of Cobi can not compare with them; yet the trades blow steadily over them, although more northerly there, as everywhere, near their northern limits, especially on land. Says Hopkins, in his atmospheric changes:“If any one part of the broad expanse of the continent of Asia could be heated so as to draw air from the Arabian Sea and the Indian Ocean during the summer, it would be that part which lies between Hindustan and the Lake of Aral, including the region between the Valley of the Oxus and Persia and the land of this part, unlike Hindustan, is not screened from the sun by thick vapours. But what says Burnes respecting the winds of this part?Why, that about the latter end of June, though the thermometer was at 103° in the day, ‘In this country a steady wind generally blows from the north.’ And on the 23d of August, after having passed the Oxus; ‘The heat of the sand rose to 150° and that of the atmosphere exceeded 100° but the wind blew steadily, nor do I believe that it would be possible to traverse this tract in summer if it ceased to blow. The steady manner in which it comes from one direction is remarkable in this inland country.’ Again; ‘The air itself was not disturbed but by the usual north wind that blows steadily in this desert.’ And he has many other similar passages.”Here there is a vast tract of country south of 35° which has a temperature often of 103° and does not reverse the trade and create a monsoon. How utterly unphilosophical, then, to attribute the monsoons to Cobi because they “obey the stronger force!” or to attribute them to it at all.4th. The monsoons can not be traced from the Malabar coast to Cobi. They do not exist on the south-west of Cobi and near it, where they should in greatest force and there is no connection, in fact, shown between them. They do not often extend more than twenty-five miles inland, or to the east of the Ghauts. There are no corresponding intervening monsoons crossing India to the mountains; none over the mountains and table lands; none under the northern lee of the mountains; nor, in short, on the whole track, nor any S. W. winds except such as naturally belong to the action of the curving counter-trade.Finally, the investigations of Commodore Wilkes on Mauna Loa, a mountain upon Hawaii, more than 13,000 feet high and the observations of Professor Wise and other aeronauts are sufficient to put this whole matter of heated lands and ascent of the atmosphere as the cause of winds, at rest. Commodore Wilkes was encamped for about twenty days on Pendulum Peak, in December and January 1840. Although not up to the elevation of the counter-trade in that latitude, he was above the local clouds which form over the island during the day, where the sea breezes blow in with as great strength as anywhere. Indeed, he was on the top of the “lofty conical mountain” to which Caleb Williams alludes in the letter to Professor Espy I have quoted and above the spot where Professor Espy assumed that the clouds were rising with such force as to induce the strong sea breezes of that island. During this time there were two snow-storms on Mauna Loa and they had the wind from the S. W. during the storm, as might be expected, looking at the situation of the mountain on the western side of the island. These storms moved to the N. W. and were observed at the other islands in that direction as rain.The local clouds lay over the island every day, as they do over active volcanic islands which are very elevated, although it was the dry season. Nothing like an ascent of the clouds or of the currents of air from the ocean was observed. On the contrary, the clouds formed before the sea breezes set in and the latter blew from the different sides of the island in under the clouds and outward again, probably on the opposite side. The whole interior of the island is elevated and its temperature low; and there was no elevation of temperature on the high portions of the island over which the clouds formed and toward which the winds blew, which could create an upward current.“During our stay on the summit, we took much pleasure and interest in watching the various movements of the clouds; this day in particular, they attracted our attention; the whole island beneath us was covered with a dense white mass, in the centre of which was the cloud of the volcano rising like an immense dome. All was motionless until the hour arrived when the sea-breeze set in from the different sides of the island; a motion was then seen in the clouds, at the opposite extremities, both of which seemed apparently moving toward the same centre, in undulations, until they became quite compact and so contracted in space as to enable us to see a well defined horizon; at the same time there was a wind from the mountain, at right angles, that was affecting the mass and drawing it asunder in the opposite direction. The play of these masses was at times in circular orbits, as they became influenced alternately by the different forces, until the whole was passing to and from the centre in every direction, assuming every variety of form, shape and motion.“On other days clouds would approach us from the S. W. when we had a strong N. E. trade-wind blowing, coming up with cumulus front, reaching the height of about eight thousand feet, spreading horizontally and then dissipating. At times they would be seen lying over the island in large horizontal sheets as white as the purest snow, with a sky above of the deepest azure blue that fancy can depict. I saw nothing in it approaching to blackness at any time.” (Exploring Expedition, vol iv. p. 155).Here, in the last paragraph, we have the whole truth disclosed. The N. E. trade was blowing on Mauna Loa, 13,000 feet above the sea and the sea-breeze blew in on the leeward side, its moisture condensing over the volcanic island but without rising up the mountain, or through the surface-trade, or above 8,000 feet.So, too, the celebrated aeronaut, Mr. Wise, in the course of more than a hundred ascensions, some during high wind and others during rain storms, never met with an ascending current, except in a single instance, in the body of a hail-cloud and then there were descending currents also, the usual intese motion of hail-cloud with its opposite polarities.I copy a description of his passage through the clouds of a rain-storm and his floating a long period above them; and there was no ascending current which disturbed their horizontal repose or progression. The double layer is not uncommon; condensation taking place at the connection of the upper and lower portions of the trades, with the surrounding atmosphere; or in the trade and by induction in the surface atmosphere at the same time. Such instances are frequently visible and if his ascensions had been undertaken at other times in stormy weather he would have seen more of them.“Before I passed the limits of the borough, a parachute, containing an animal, was dropped, which descended fast and steady, and, just as it reached the earth, my ærial ship entered a dense black body of clouds. Ten minutes were consumed in penetrating this dismal ocean of rainy vapour, occasionally meeting with great chasms, ravines and defiles, of different shades of light and darkness. When I emerged from this ocean of clouds, a new and wonderfully magnificent scene greeted my eyes. A faint sunshine shed its warmth and lustre over the surface of this vast cloud sea. The balloon rose more rapidly after it got above it. Viewing it from an elevation above the surface, I discovered it to present the same shape of the earth beneath, developing mountains and valleys, corresponding to those on the earth’s surface. The profile of the cloud-surface was more depressed than that on the earth, and, in the distance of the cloud-valley a magnificent sight presented itself. Pyramids and castles, rocks and reefs, icebergs and ships, towers and domes; every thing belonging to the grand and magnificent could be seen in this distant harbor; the half-obscured sun shedding his mellow light upon it, gave it a rich and dazzling lustre. They were really “castles in the air,” formed of the clouds. Casting my eyes upward, I was astonished in beholding another cloud-stratum, far above the lower one; it was what is commonly termed a “mackerel sky,” the sun faintly shining through it. The balloon seemed to be stationary; the clouds above and below appeared to be quiescent; the air castles, in the distance, stood to their places; silence reigned supreme; it was solemnly sublime. Solitary and alone in a mansion of the skies, my very soul swelled with emotion; I had no companion to pour out my feelings to. Great God, what a scene of grandeur! Such were my thoughts; a reverence for the works of nature, an admiration indescribable. The solemn grandeur; the very stillness that surrounded me; seemed to make a sound of praise.“This was a scene such that I never beheld one before or after exactly like it. Two perfect layers of clouds, one not a mile above the earth; the other, about a mile higher; and, between the two, a clear atmosphere, in the midst of which the balloon stood quietly in space. It was, indeed, a strange sight; a meteorological fact, which we cannot possibly see or make ourselves acquainted with, without soaring above the surface of the earth.” (History and Practice of Aeronautics, p. 209).This is graphic. Perhaps in relation to the conformity of the upper surface of the inferior layer of clouds, to the irregularities of the earth’s surface, he was misled during the enthusiasm of the moment. He is certainly mistaken as to the possibility of observing these double layers from the earth; I have seen them in hundreds of instances. But in relation to the quiescence of the clouds for an hour and the entire absence of ascending currents, he could not be mistaken.And now, in the absence of all direct proof to sustain the hypothesis, that the heating of the land produces ascending currents and thereby the winds and especially the monsoons and in view of all the adverse evidence, I put it to Lieutenant Maury and every sincere searcher after meteorological truth, whether the theory should not be abandoned.
I have just put a load of stuff on my blog. Please don't be put off when you find it impossible to understand. I am sure I have only been following half of it. The last few chapters I have just skimmed through as they were almost meaningless to me.Chapter 6 was a monster and it gets worse after that:
CHAPTER VII.The counter-trade of the northern hemisphere ranges at different heights in different latitudes, in the same latitude at different seasons and also upon different days of the same season; and, like the line of perpetual snow, has its greatest elevation in the tropics, descending gradually to the surface of the ocean at the poles. At the northern limit of the N. E. trades, it does not, ordinarily, approach the earth sufficiently near for decided reciprocal action. Hence, at that point, storms do not often originate; the winds are lighter and more variable and calms are more frequent than at any point, except at the meeting and elevation of the trades, or in the polar regions. Doubtless this state of things is increased by the feebler action of north polar magnetism and the irregular action of the longitudinal magnetic currents, evinced by the irregular and often, feeble action of the trades, near their extreme limits. They are not infrequently wholly wanting, near the northern limit, for several days in succession and calms and baffling winds are found in their place; another effect of the irregular action of terrestrial magnetism, consequent upon the ever-changing transit of central activity from south to north and from north to south. Upon the islands, however and continents, which have elevated mountain peaks and ridges, especially if of volcanic origin and activity, which approach more nearly the path of the counter-trade, a different state of things exists. There, showers and gusts are frequent. Thus, upon the Sandwich Island, Kauai, the most northern one, which is within the region of the N. E. trade during ten months of the year and upon its volcanic peaks and elevated table-lands and north-easterly from them, over the district of Waioli, rain falls in abundance during the year, while the coastlines upon other portions of the island can not be cultivated without irrigation. (See Wilkes’ Exploring Expedition, vol. iv. pp. 61 and 71; and American Journal of Science and Art, for May, 1847).A like state of things, in degree, may be found upon the Canaries and the more elevated of the West India Islands. The Cape de Verdes are an exception and the Christian world are quite often called upon for contributions of provisions, to save the inhabitants of these islands from starvation. They lie at the northern limit of the equatorial belt and for a period of two months only (July and August), are supplied with rain. If, from any cause, the belt does not move as far north as usual during any season, unbroken drought and famine are sure to overtake them. The islands contain some elevated peaks and are of volcanic origin but not of present volcanic activity and the counter-trades as they issue from the equatorial belt at their highest elevation, are too far above them for reciprocal, influential action. If the islands could be placed 10° further north, we should hear no more of drought or famine from them and their quantity of rain and fertility would be not only more permanent but much increased. Superadded to this, is the fact, that at that point the belt of rains precipitates feebly because the S. E. trade originates upon the southern part of the continent of Africa and the N. E. mainly, upon the desert and the Barbary States; and both are sparingly supplied with moisture.The same state of things is strikingly obvious upon continents wherever the mountains are sufficiently elevated, even within the trade-wind region. Thus, in South America, the Andean ranges are of great elevation and spurs and table-lands extend from them a considerable distance to the eastward. There, the S. E. and N. E. trades of the Atlantic meet in very considerable volumes and not only is the equatorial belt much wider than upon the Atlantic and Pacific but the counter-trades are met upon the elevated peaks and mountain-ranges and showers and storms on their eastern slopes and summits are frequent during the dry season; down even to the extra-tropical belt. I have already said that it was probable that the great elevation of the Andes diverted and turned south a portion of the N. E. counter-trade which would otherwise pass over the western coast of Peru.The report of Lieutenant Herndon, which has come to my notice since that was written, states facts which strongly corroborate that opinion. It seems that the trades and counter-trades actually bank up, in their passage to the westward, against those mountains and the true elevation of their eastern slopes can not be barometricly ascertained. (See report of the Exploration of the Amazon, p. 261). Lieutenant Herndon says:“I was surprised to find the temperature of boiling water at Egas to be but 208° 2′, the same within 2′ of a degree that it was at a point one day’s journey below Tingo Maria, which village is several hundred miles above the last rapids of the Huallaga river; at Santa Cruz, two days above the mouth of the Huallaga, it was 211° 2′; at Nauta, three hundred and five miles below this, it was 211° 3′; at Pebas, one hundred and seventy miles below Nauta, 211° 1′. I was so much surprised at these results that I had put the apparatus away, thinking that its indications were valueless; but I was still more surprised, upon making the experiment at Egas, to find that the temperature of the boiling water had fallen 3° below what it was at Santa Cruz, thus giving to Egas an altitude of fifteen hundred feet above that village, which is situated more than a thousand miles up stream of it. I continued my observations from Egas downward and found a regular increase in the temperature of the boiling water until our arrival at Pará, where it was 211° 5′.“From an after-investigation, I am led to believe that the cause of this phenomenon arises from the fact that the trade-winds are dammed up by the Andes and that the atmosphere in those parts is, from this cause, compressed, and, consequently, heavier than it is further from the mountains, though over a less elevated portion of the earth. The discovery of this fact has led me to place little reliance in the indications of the barometer for elevation, at the eastern foot of the Andes. It is reasonable, however, to suppose that this cause would no longer operate at Egas, nearly one thousand miles below the mouth of the Huallaga.”The report of Lieutenant Gibbon, is also exceedingly instructive. Separating from Lieutenant Herndon at Tarma, upon the Andes, he pursued a southern course, along the eastern slopes of the chain from 11° 30′ south, almost to 18° south, at Ohuro, making a journey of about 7° 30′ of latitude.A considerable portion of this journey was over eastern and less elevated portions of the Andes; but little below, however, the line of perpetual snow. Here, during the dry season, he met with frequent showers and fogs from the eastward but left them as he descended into the plains upon the table-land. There he found the dry season more distinctly marked; but occasional irregularities were found upon the table-lands, as everywhere upon corresponding elevations. The S. E. trades, however, were there obvious, during the dry season, notwithstanding the irregularities. The rainy season, from December to May, he spent at Cochabamba and at its close he travelled north down the Madeira and its tributaries, to the Amazon. Although scarcely consistent with my prescribed limits, I can not forbear making a few extracts. Thus, when on the mountains, east of Huanvelica, in the N. E. counter-trade, he says:“Our course is to the eastward. The snow-capped mountains are in sight to the west. Temperature of a spring 48°; air 44°. Lightning flashes all around us; as the wind whirls from north-east to south-west, rain and snow-flakes become hail, half the size of peas. Thunder roars and echoes through the mountains; the mules hang their heads and travel slowly; the thinly-clad aboriginal walks shivering as he drives the train ahead; the dark cumulus cloud seems to wrap itself around us.”Again, at the Bombam Post-house, in the focus of change from cirrus to cumulus and stratus and storm:“The winds are very gentle and curl the cirrus or hairy clouds in most graceful shapes about the hoary-headed Andes, in rich and delicate clusters; when the peak is concealed, all but the blue tinge below the snow, we see a natural bridal veil. An easterly wind lifts and turns them to dark, cumulus clouds, settled on the frosty crown, like an old man’s winter cap; the physiognomical expression is that of anger. The change is accompanied by thunder and seems to command all around to clothe themselves for storms. The cold rain comes down in fine drops upon us; the day grows darker and the clouds press close upon the earth.”During an excursion east of Cuzco; “Turning from the river, we ascend a steep ridge of mountains; the eastern range at last. A heavy mist wafts upward as the winds drive it against the side of the Andes, so that our view is shortened to a few hundred yards. We hope the curtain will rise that we may view the productions of the tropical valley below; but the mist thickens and the day gets dark with heavy, heaped-up black clouds; a rain-storm follows. The grasses are thrifty and the top of the ridge covered with a thick sod. By barometer, we stand eleven thousand one hundred feet above the level of the sea.”In May following, having spent the rainy season in Cochabamba, he travels north; “Our route from Tarma to Oruro was south. We travelled ahead of the sun. In December, when we arrived in Cochabamba, the sun had just passed us. As soon as he did so, the rains descended heavily on this side of the ridge; it was impossible to proceed. The roads were flooded, the ravines impassable and the arrieros put off their journey until the dry season had commenced. After the sun passed the zenith of Cochabamba and had fairly moved the rain belt after him toward the north, then we came out from under shelter and are now walking behind the rain belt in dry weather, while the inhabitants are actively employed in tending their crops.”So on the north of the equatorial belt, along the whole line of the Andes, up to the northern boundary of the desert valley of the Gila, rain falls on the high mountain-ranges, owing to the contiguity of the counter-trade and the diversion of showers to the north, along their eastern sides.During the survey of the boundary line between Mexico and California, etc., by the commission under Mr. Bartlett, it became necessary to find some spot where water and grass were abundant, for the head quarters of the commission. This was found and could only be found, upon the Mimbres Mountains, at an old abandoned Spanish copper mine, 7,000 or 8,000 feet above the level of the sea, surrounded with peaks of still greater height. These elevated ranges were within influential distance of the counter-trade and here snow fell in the winter, from the extra-tropical belt and rain, in showers, in summer, at the period of the most northerly extension of the tropical belt; when fifteen miles off, in the valley, it was unbroken drought. Mr. Bartlett thus describes it in his Personal Narrative:“We reached this district on the 2d of May. Vegetation was then forward, though there had been no rain. But it must be remembered that during the winter there is snow and hence a good deal of moisture in the earth when the spring opens. The months of May and June were moderately warm. On the third of July the first rain fell. It then came in torrents, accompanied by hail and lasted three or four hours. Many of our adobe houses were deluged with water and the mountain-sides exhibited cataracts in every direction. The Arroyo, which passes through the village and which furnishes barely water enough for our party and the animals, became so much swollen as to render it difficult to cross; and, by the time it had received the numerous mountain torrents, which fall into it within a mile from our camp, it became impassable for wagons, or even mules. The dry gullies became rapid streams, five or six feet deep and sometimes fifty feet or more across. On this day, a party, in coming to the copper mines, from the plain below, where there had been no rain, found themselves suddenly in a region overflowing with water, so that their progress was arrested and they were obliged to wait until the flood had subsided. After this we had occasional showers, during the months of July and August.”The location of this mountain station is near the thirty-third degree of north latitude, while the northern limit of the equatorial belt, nowhere, except upon the mountain ranges and table-lands of Mexico, extends above 25°.There, for the reason we have been considering, it does extend further north during July and August, in occasional showers and in the vicinity of Mount Picacho, Mr. Bartlett met one of its mountain thunder-storms on the 13th of July, on his return south through Mexico, in latitude 32°, in the following year. (Personal Narrative, vol. ii. p. 285). These showers originated in strata of counter-trade, which had followed up along the eastern side of the mountains and not from strata which had crossed them and curved to the eastward, as is shown by the course of progression of the showers.Let us look, in this connection, at a fact or two of great interest, though not directly connected with the point in hand. The southern limit of the extra-tropical belt in winter, on the Pacific coast of North America, is in the vicinity of San Diego, at about 32°. In summer, that limit is carried up above Astoria, which is in latitude 46° 11′; about 14°; yet New Mexico receives little if any rain in winter in the vicinity of Albuquerque but does receive a limited supply of about seven inches in summer and autumn, five and a half inches of which falls in June, July and August. Albuquerque is in latitude 35° 13′, below the southern summer limit of the extra-tropical belt and north of the northern limit of the equatorial belt. This anomaly is explained by the extension west over northern New Mexico, of the extreme western edge of our concentrated counter-trade, by reason of its issuing further west from the equatorial belt in its northern extension in the summer months. This western edge, in curving to the east, north-east of New Mexico, covers the north-western States, Iowa, Minnesota, Wisconsin, etc. and furnishes them that great excess of summer precipitation which is a peculiarity of their climate; and its absence further east in winter and the very great elevation of the Rocky Mountains and other ranges over which their ordinary counter-trade of that season curves, account for the absence of much precipitation and snow there, or over the valley of the Rio Grande in New Mexico, in winter.We may now see, too, why the western coast and the Pacific region of the continent, below 45°, are so deficient in moisture. The S. E. trades, which arise from the western portion of the south Atlantic and the continent of South America, which, if it were not for the Andes chain, in their natural course, after passing the equatorial belt, would continue on to the north-west until they passed the limits of the N. E. trades and curve in upon the western portion of our continent below 45° and supply it bountifully with rain, are, in part, perhaps, diverted along the eastern side of those mountains to swell the volume of our counter-trade and in part pass them, almost exhausted of their supply of moisture by their contiguous reciprocal action. Hence, too, the deficiency of precipitation at the base of the Andes, on the western side and the peculiar and irregular character of the winds under the western lee of the Andean range. Baffling airs and bands of calms prevail on this portion of the Pacific, except where the mountains fall off and then there is a westerly or south-westerly monsoon under the equatorial belt. Says Lieutenant Maury in his Charts, sixth edition, p. 731:“The passage, under canvass, from Panama to California, as at present made, is the most tedious, uncertain and vexatious that is known to navigators.“My investigations have been carried far enough to show that at certain seasons of the year a vessel bound from Panama to California, must cross at least three, at some seasons four, such meetings of winds or bands of calms, before she can enter the region of the N. E. trades. Hence the tedious passage.”Such will ever be the state of things on this continent and upon the eastern Pacific, so long as the S. E. counter-trades are compelled to pass over the mountain chain of South and Central America.Again, if we examine carefully the belt or zone of extra-tropical rains, we shall find that the focus of greatest precipitation is considerably north of its southern limit and that, other things being equal, this focus travels north in summer and gives to higher latitudes their needed summer rains. This is very apparent upon the north-western portion of our continent, as the following table will show: Lat. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Year.San Diego, Cal. 32° 41′ 0.3 1.7 1.1 0.9 0.5 0.0 0.0 0.2 0.0 0.1 1.5 3.4 9.6San Francisco. 37° 48′ 1.7 0.5 4.4 2.1 0.4 0.0 0.0 0.0 0.4 0.6 3.0 5.5 18.8Cant., Far W., Cal. 39° 02′ 3.3 0.6 6.4 2.2 0.9 0.0 0.0 0.0 0.3 0.1 3.5 4.6 21.9Astoria, Oregon. 46° 11′ 27.0 10.9 6.1 4.4 5.9 2.6 0.0 2.3 1.9 6.7 13.2 6.2 87.2Puget’s S’d, Ore. 47° 07′ 11.8 3.9 4.7 4.1 0.8 0.6 0.5 1.3 1.6 3.6 5.9 6.1 44.8Sitka, Russ. Am. 57° 3′ 2.5 9.6 3.5 3.3 1.9 5.9 3.7 10.1 14.8 12.7 7.4 4.2 79.5The figures are for inches and tenths of an inch of rain.Thus, it will be seen that in January, when the southern line is at San Diego, at the south line of California, the focus of precipitation is over Oregon; and that in August and September when the southern line is carried up and over Oregon, the focus has travelled north to Sitka and that it is always at least 10° north of the southern line of the belt upon that coast. The increased quantities of rain which fall at the focus of precipitation there, from Oregon up, are doubtless much enhanced by the equatorial oceanic current which flows over opposite that part of the continent. A like effect, precisely, is produced in Europe. The quantity of rain which falls at Bergen, in Norway, being 8761⁄100 inches per year, more than three times the average for that continent.The difference shown in the foregoing table, between Astoria and Puget’s Sound, is owing to the fact that the latter lies in the interior and within the coast range of mountains, while Astoria is situated at the mouth of the Columbia River, with an open view of the ocean.A like comparative increase of precipitation in northern latitudes, in summer, is found everywhere varying according to the local influences which operate in the particular case. Thus,There falls in Winter. Spring. Summer. Autumn. Year.Burlington, Vt., lat. 44° 20′ 5.7 7.3 11.4 9.8 33.9Albany, N. Y., lat. 42° 39′ 8.3 9.8 12.3 10.3 40.7Minnesota, Iowa, lat. 41° 28′ 7.3 12.3 17.4 11.7 48.8St. Peters’g, Russ., lat. 59° 56′ 3.89 3.20 5.70 4.71 17.51Pekin, China, lat. 40° .54 3.35 18.80 2.29 25.68Pekin lies in the northern part of China and would have a much larger fall of rain from a concentrated counter-trade but for the numerous mountain-ranges which intersect its path in winter but over which it passes at a greater elevation during the summer; a peculiarity from which the eastern section of this country is most remarkably and happily free.Thus, it is obvious that the focus of precipitation in the zone of extra tropical rains, is some 8° to 12° north of its southern line and travels with the whole machinery in its annual transit north and south.It is a question of some difficulty, perhaps, whether this focus is increased by the increase of magnetic action at this point, for both the line of descent of the counter-trade and the focus of magnetic action, are carried up in a like manner and for a like cause, and, in all probability, both concur in the result.There is exceeding wisdom in this provision for the gradual subsidence of the counter-trade, and gradual increase of magnetic intensity and consequent gradual precipitation. On the European continent and over western Asia, there are 50° of latitude to be supplied with moisture by this polar belt of rains. If the focus of precipitation was at its southern border, the counter-trade would be deprived of its moisture at that point and little would reach the more northern portions of the globe which are to be supplied by it. But the movement of the whole machinery carries up the southern line from the south boundaries of the Barbary States on to the Mediterranean and portions of southern Europe and the focus of precipitation and of near approach of the counter-trade to the earth, being situated far north of the southern line, is carried up correspondingly, while the combination of the moisture with the atmosphere by south polar magnetism and electricity and the gradual descent of the counter-trade, enable it to resist, to some extent, the influence of north polar magnetism and cold and thus retain portions of its moisture for distribution in the polar regions.The elevation of the counter-trade above the earth varies in the same latitude with the variations in the phenomena of the weather. An attentive observation of the clouds of our climate will soon satisfy any one of this, after he has become familiar with them, so as to distinguish with certainty the clouds of the trade. Its range, in this country, is from 3,000 feet, or less, to 12,000 feet above the earth and its depth with us probably, from 6,000 to 8,000 feet. Gay-Lussac, in his scientific experimental balloon ascension, the first of that character ever made, except an imperfect one just previous, by himself and Biot, found it at about 12,000 feet over Paris and about 4,000 feet in depth. It is detected by the thermometer when much elevated.The atmosphere grows cool as it is ascended on mountains, or by balloons. The rate of cooling is ordinarily about 1° of Fahrenheit for every 300 feet. If it were not for the equatorial current, this progressive decrease of temperature would doubtless be perfectly uniform. Of Gay-Lussac’s ascension, on this point it was said:“At forty minutes after 9 o’clock, on the morning of the 15th September, 1804, the scientific voyager ascended, as before, from the garden of the repository of models. The barometer then stood at 30.66 English inches, the thermometer at 82° Fahrenheit and the hygrometer at 57½°. The sky was unclouded but misty.“During the whole of this gradual ascent, he noticed, at short intervals, the state of the barometer, the thermometer and the hygrometer. Of these observations, amounting in all to twenty-one, he has given a tabular view. We regret, however, that he has neglected to mark the times at which they were made, since the results appear to have been very materially modified by the progress of the day. It would likewise have been desirable to have compared them with a register, noted every half hour, at the Observatory. From the surface of the earth to the height of 12,125 feet, the temperature of the atmosphere decreased regularly, from 82° to 47° 3′ by Fahrenheit’s scale; but afterward it increased again and reached to 53° 6′ at the altitude of 14,000 feet; evidently owing to the influence of the warm currents of air which, as the day advanced, rose continually from the heated ground. From that point the temperature diminished, with only slight deviations from a perfect regularity. At the height of 18,636 feet the thermometer subsided to 32° 9′, on the verge of congelation; but it sunk to 14° 9′ at the enormous altitude of 22,912 feet above Paris, or 23,040 feet above the level of the sea, the utmost limit of the balloon’s ascent.”The high range of the barometer indicated a very considerable elevation of the trade at the time Gay-Lussac made his ascension. I am not aware that it has since been found at so great an elevation, in so high a latitude, though it is undoubtedly elevated by the interposition of a large volume of N. W. air, upon some occasions, to nearly the same altitude with us.In the extract in relation to the ascension of Gay-Lussac, we have another of the thousand hastily-adopted and absurd hypotheses connected with the caloric theory. It is obviously and utterly impossible that in addition to the ordinary accumulation of heat at the surface of the earth “as the day advanced”; that is, during the forenoon, warm currents should ascend, unobserved by Gay-Lussac during an ascent of 12,000 feet; not affecting in the least so large an intervening body of the atmosphere or his thermometer and in such immense volumes as to increase the warmth of a stratum of 4,000 feet in depth, an average of 3° of Fahrenheit and to the extent of 6° at the centre.Very few balloon ascensions have been made with a view to scientific and accurate observation. But other aeronauts have met the counter-trade at different altitudes and in both clear and stormy weather.Recently, in 1852, four ascensions were made in England, under the direction of the Kew Observatory Committee, of the British Association. I copy from the August number of the “London, Edinburg and Dublin Magazine,” for 1853, the following condensed amount of the result:“The ascents took place on August 17th, August 26th, October 21st and November 10th, 1852, from the Vauxhall Gardens, with Mr. C. Green’s large balloon.“The principal results of the observations may be briefly stated as follows:“Each of the four series of observations shows that the progress of the temperature is not regular at all heights but that at a certain height (varying on different days) the regular diminution becomes arrested and for the space of about 2,000 feet the temperature remains constant, or even increases by a small amount. It afterward resumes its downward course, continuing, for the most part, to diminish regularly throughout the remainder of the height observed. There is thus, in the curves representing the progression of temperature with height, an appearance of dislocation, always in the same direction but varying in amount from 7° to 12°.“In the first two series, viz.: August 17th and 26th, this peculiar interruption of the progress of temperature is strikingly coincident with a large and rapid fall in the temperature of the dew-point. The same is exhibited in a less marked manner on November 10th. On October 21st a dense cloud existed at a height of about 3,000 feet; the temperature decreased uniformly from the earth up to the lower surface of the cloud. When a slight rise commenced, the rise continuing through the cloud and to about 600 feet above its upper surface, when the regular descending progression was resumed. At a short distance above the cloud, the dew-point fell considerably but the rate of diminution of temperature does not appear to have been affected in this instance in the same manner as in the other series; the phenomenon so strikingly shown in the other three cases being perhaps modified by the existence of moisture in a condensed or vesicular form.“It would appear, on the whole, that about the principal plane of condensation heat is developed in the atmosphere, which has the effect of raising the temperature of the higher air above what it would have been had the rate of decrease continued uniformly from the earth upward.”These gentlemen do not adopt the absurd explanation of the French philosophers; they account for the phenomenon by supposing heat to be developed at that particular part of the atmosphere; but they are equally wide of the mark. They found the excess of heat there to the extent of 7° to 12° and on days when there was no condensation, or other assignable cause for its development.The temperature of the counter-trade partakes, doubtless, of the temperature of the adjoining strata at its upper and lower portion and has never been found much, if any, higher than 60° at the centre. Nor could it be expected. The trade, in its upward curving course, within the tropics, attains a considerable altitude where the atmosphere is comparatively cold and necessarily loses a portion of its heat there and during its northern flow. Probably its central summer range, in the latitude of Paris, is not far from 55° and with us 60°.The contrast between the trade and the surrounding atmosphere, in winter, is much more striking and this has been observed particularly upon the Brocken of the Alps and in the polar regions.“In all seasons the temperature is higher on the Brocken, on a serene, than on a cloudy day, and, in the month of January, the serene days were warmer than at Berlin.” (Kämtz’s Meteorology, by Walker, p. 217.; Note.)As the portion of the counter-trade, which does not become depolarized; in diminished volume; progresses toward the polar regions, it settles nearer the earth and within the Arctic circle is found but little way above it. Thus, in December, 1821, Parry, at Winter Island, in latitude 66° 11′, flew a kite, with a thermometer attached, to the height of 379 feet and found that the temperature, instead of falling 1¼°, the usual ratio of decrease, rose ¾ of a degree.The same thing was observed at Spitzbergen, in latitude 77° 30′ north and at Bosekop, latitude 69° 58′, by a scientific commission and by means of kites, confined balloons and the ascent of elevations.“In winter the temperature goes on increasing with the height, up to a certain limit, which is variable, according to the different atmospheric circumstances, the influence of which is not yet very exactly known. The hour of the day appears to be indifferent, since there exists no thermometric diurnal variation in the strata of the surface. The mean of thirty-six experiments, made with kites, or with captive balloons, at Bosekop, latitude 69° 58′ north, has given a mean rate of increase of 1° 6′ for the first hundred meters.[6] Beyond this limit and even beyond the first 60 or 80 meters, the temperature again becomes decreasing, at first very slowly but afterward the decrease is accelerated. The observations that have been made on the flanks, or on the summits, of mountains, during the same expeditions, entirely confirm these results. The cooling influence of a soil, that radiates its own heat for several weeks, without receiving any thing on the part of the sun, in compensation of its losses, the influence of counter-currents from above, coming from the west and the south-west, with a high temperature, account for this anomaly, which, in winter, represents the normal state of the most northern parts of the European continent.” (Walker’s Kämtz, p. 515.; Note.)Mr. Walker is the only author, so far as I know, who has suspected the true cause of the phenomenon, viz.: “currents from above coming from the west and south-west, with a high temperature;” but the caloric theory “sticks like a burr,” and he adheres also to the idea that a snow-clad surface, in the absence of the sun, can aid, by radiation, in warming the atmosphere for a distance of several hundred yards above it, increasing the warmth as the distance from the earth increases!This contrast between the counter-trade and the adjacent atmosphere, in winter, in latitudes as low as that of the Brocken, is probably heightened by the increased warmth of the former, at that season. The S. E. trades then form under a vertical sun and the difference of temperature can not be less than from 6° to 8°. Not infrequently in winter and spring the rain will fall with a temperature of 50° to 55°, when the atmosphere near the earth is 10° or 20° or more, below those points; and it is frozen to every object upon which it falls. The trade stratum, from which it descends, is not warmed by “radiation” or by ascending currents from a snow-clad surface and during a cloudy day; nor by a “development of heat” at that particular altitude but it has brought its heat from the South Atlantic and imparts it to the rain which forms within it. There is every reason to believe that the counter-trade flows north in a regular descending plane, not materially differing from that of the line of perpetual snow. The descent of the latter is well ascertained to be from about 16,000 feet at the equator, to the surface at the poles. The plane of the counter-trade is probably much the same, varying over different localities, from the varied action between it and the earth which we are considering; and probably both correspond with the increase of magnetic intensity.Lieutenant Maury, in an able and original article upon the circulation of the atmosphere, conceives the bands of comparative calms at the northern limits of the trades, which he appropriately terms the “Calms of Cancer,” to be nodes in the circulation of the atmosphere and that the upper or counter-trade here descends and becomes a surface wind from the S. W., as the N. E. trade is a surface wind; and that an upper current from the poles approaches and descends at the same node, to make the N. E. trade. But it is evident he adopted that conclusion too hastily, as he obviously did the conclusion that the calms of the horse latitudes were a type of all. We have seen that the latter are increased by a diversion of the counter-trade and that they are avoided by making easting. So it may be observed that our upper current is a S. W. current and no northerly upper current is visible, or exists over the country, however it may be in western Europe and the North Pacific, on the west of the magnetic poles, where cold, dry northerly and north-easterly winds are found. The origin and progress of storms withal demonstrates that no such node can exist.Two points have been made in relation to the course of the counter-trade in the tropics and are relied upon to show its progress there to the N. E., which deserve consideration.In the first place, it is well known that “rain dust” falls in considerable quantities on the western coast of Africa, particularly about the Cape de Verde Islands and also upon the Mediterranean and south-western Europe, where it is termed “sirocco dust.”“This dust,” says Lieutenant Maury, “when subjected to microscopic examination, is found to consist of infusoria and organisms, whose habitat (place of abode) is not Africa but South America, and in the S. E. trade-wind region of South America. Professor Ehrenberg has examined specimens of sea dust, from the Cape de Verdes and the regions thereabout, from Malta, Genoa, Lyons and the Tyrol and he has found such a similarity among them as would not have been more striking had these specimens been all taken from the same pile.“South American forms he recognizes in all of them; indeed, they are the prevailing form in every specimen he has examined.“It may, I think, be now regarded as an established fact, that there is a perpetual upper current of air from South America to north Africa and that the volume of air in these upper currents, which flows to the northward, is nearly equal to the volume which flows to the southward with the N. E. trade-winds, there can be no doubt,” etc.Now, it is doubtless true that this dust is transported in a counter-trade and that such dust is found in South America and is taken up there by sand-spouts, like those of the ocean in form and action. Both Humboldt and Gibbon have graphically described them. Yet I do not think the point well taken. South-eastward of the Cape de Verdes, where the surface-trades; which, becoming counter-trades, pass over these islands, and, recurving, pass over the Mediterranean and south-western Europe; should originate, there is a vast extent of unexplored continent in the same latitude as the portion of South America where the dust is found; and the same dry seasons and the same spouts, in all probability, exist in both. Until it be shown that such forms have no “habitat” in central and southern and unexplored Africa, upon the same latitudes as in South America, it may fairly be presumed that the dust is taken up there. Indeed, the curve upon which this dust is found to fall, in the greatest quantities, is very remarkable and corresponds remarkably with the law of curvature of the counter-trade we have considered and with the progress of a storm upon that coast and over the Mediterranean, investigated by Colonel Reid. (See Reid, on Storms and Variable Winds, p. 276.) This curve clearly indicates the origin of the dust in South Africa.The second point is, that ashes from the volcanoes of Mexico and Central America have fallen to the north-east of the place where they were ejected. Mr. Redfield has grouped these instances of volcanic eruption usually cited and I copy from him:“We learn from Humboldt, that in the great eruption of Jorullo, a volcano of southern Mexico, which is 2,100 feet above the sea, in latitude 18° 45′, longitude 161° 30′, the roofs of the houses in Queretaro, more than 150 miles north, 37° east from the volcano, were covered with the volcanic dust. In January, 1845, an eruption took place in the volcano of Cosiguina, on the Pacific coast of Central America, in latitude 13° north and having an elevation of 3,800 feet, the ashes from which fell on the island of Jamaica, distant 730 miles north, 60° east from the volcano. The elevated currents by which volcanic ashes are thus transported are seldom or never of a transient or fortuitous character; and these results, therefore, afford us one of the best indications of their general course. Thus, the progress of the higher portion of the trade-wind was marked by the eruption of Tuxtla, latitude 18° 30′, longitude 95°, which covered the houses in Vera Cruz with ashes, at the distance of 80 miles north, 55° west and also at Peroté, 160 miles north, 60° west. The ashes from the volcano, at St. Vincent, which fell at Barbados and east of that island, in 1812, mark the course of a current from the westward, which appears there at times, in the region of clouds and may, perhaps, be connected with the permanent winds on the Pacific coast of Mexico.”As to one of the instances cited in the foregoing paragraph, that of Tuxtla, it may be laid out of the case; the direction conforming substantially to the assumed course of the counter-trade at that point. St. Vincent lies W. N. W., or nearly so, of Barbados and a N. W. or westerly surface-wind, prior to and during storms, is common in the West Indies as the N. E. is here; both alike, blowing in opposition to the progressive course of the storm. There is nothing strange or peculiar, therefore, respecting that instance, or the existence of variable and especially S. W. currents, between the trades, with occasional partial condensation.The falling of the ashes from Cosiguina, upon Jamaica, has long and often been cited, as proof that in the West Indies the prevailing upper currents run from the S. W. But it has been ascertained that, during the same eruption, ashes fell 700 miles to the westward, on the deck of the Conway, a vessel then upon the Pacific Ocean. That case, therefore, does not prove the absence of the S. E. counter-trade at the time but only the presence of another and a different current above or below it; and it may have been either and transient.So of the Jorullo instance. Investigation would probably have shown that ashes fell to the N. W. and that they were carried N. E. by a transient S. W. wind produced by the existence of a storm to the eastward, or one of those states of partial condensation of the counter-trade which often produce currents at greater distances without a storm. Not one of these cases disproves the existence of a S. E. counter-trade and the invariable N. W. progression of the storms of those latitudes demonstrates it.Occasional anomalous currents, depending upon storm action at considerable distance, are found in our atmosphere and doubtless are there also. Thus, although the N. W. wind is almost invariably a surface wind, I have, in a few instances, seen a N. W. set at a considerable elevation, converging toward a peculiarly stormy state of atmosphere far south of us, about the period of the spring equinox. And so in one or two instances I think I have seen light cirro-stratus clouds above the counter-trade, when it ran very low, setting from the N. E., although the usual and almost invariable location of the N. E. wind is below the counter-trade and the stratus clouds of the storm. Aeronauts, too, have found these secondary currents beneath a serene and cloudless sky. Indeed, the S. E. counter-trade doubtless often induces a thin secondary current of S. W. wind between itself and the surface-trade, in the same manner that similar currents are induced with us and everywhere.A question arises here of considerable interest, which, I confess, I can not answer to my own satisfaction. It is, whether there be, or not, an eastern progression of the body of the atmosphere above the machinery of distribution. I have thought there was and that in set fair weather I had seen a peculiar kind of cirro-cumulus cloud, in patches, the small cumuli very distinct and rounded, moving due east, which indicated such a current. But I am not satisfied, from my own observation, that it is so, nor is it easy to determine the question. The moisture of evaporation rarely, if ever, ascends to any considerable elevation and the upper strata must be very dry. Hence, condensation, if it takes place, is thin and perhaps often undiscernible. Investigations upon mountains prove little, for the winds of the inferior strata rush up their sides and over them. It is an open question and future observation may solve it. The prevailing opinion seems to be that there is. If the theory of Oersted, in relation to the circular currents of a magnet, be true, there should be such a progression produced by opposite secondary currents, unless, indeed, it be also true that those currents are inoperative at so great a distance, or their influence barely suffices to retain the attenuated atmosphere in its place. Perhaps the investigations of Ampère conflict with it. But it is worth while, I think, for philosophers to inquire whether the transverse position of the needle upon the wire is not the effect of the central longitudinal currents, conforming to the circular currents of the wire and whether it is not owing to the production of the same currents in a globe by the circular currents of Ampère, that the globe is magnetized and the needles made to dip.
Well that is as far as I have read. I will have to consult an online version to get all those charts from the lst 3 chapters. I lashed them up as best I could after Open Office and Microsoft had a bsh at them. If I save them to spread sheets I should be able to understand what the author was trying to explain but frankly, his ancient views and his explanations to the then current thinking has left me somewhere along the track looking off into the wrong direction for something I am not sure what I'm supposed to be seeing.(But I am pretty good at that.)((I have had enough for now, though!))
From a large number of logs examined by Lieutenant Maury, the mean elevation in the N. E. trades of the Atlantic was 29.97⁄100; the S. E. trades of the Atlantic, 29.93⁄100; off Cape Horn, 29.23⁄100; S. E. trades of the Pacific, 30.05⁄100; N. E. trades of the Pacific, 29.96⁄100. The height of the barometer off Cape Horn is not a fair index of the general elevation of the southern hemisphere, inasmuch as it stands lower there than at the coast of Patagonia and Chile, or at most, if not all, other stations in that hemisphere.As the barometer is constantly oscillating up and down (irrespective of its diurnal oscillation), it has no known fair weather standard. The point of 30 inches is taken only as it is a mean. I have known it to commence storming when the barometer was at 30.70 and not to fall before it cleared off, below 30.30. And I have known it to be below 30 for several days consecutively, with fair weather. In our climate there is no reliable fair weather standard for the barometer. It falls below 30 without storming; it rises far above and storms without falling below. No reliance can be placed upon its elevation, except by comparison; but of that hereafter.The general rule, nevertheless, is, that it falls more or less during storms, whatever its height and rises sooner or later, more or less, after they clear off.The difference between its highest and lowest points is called its range. The greatest range observed and recorded, is about 3 inches; from about 28 to 31; but this range is rare. The range, in the trade-wind region, is comparatively small; in this country it is greater than in Europe; and, generally, the range will be found greatest where the volume of counter-trade and magnetic intensity and the corresponding amount of precipitation and extremes of heat and cold are greatest. One of the greatest ranges during one storm, or two successive portions of a storm, in this country, which I have seen recorded, occurred at Boston, in February, 1842. It was as follows; counting the hours as 24 and from midnight:Feb. 15..10h..30.36." 16..13h..28.47 fall of 1.89 in 27 hours." 17..19h..30.39 rise of 1.92 in 30 hours." 18.. 2h..30.39 stationary 5 hours." 19.. 2h..29.46 fall of 0.93 in 24 hours." 20.. 2h..30.43 rise of 0.97 in 24 hours. Amount of oscillation, 5.71 in 4 days, 11 hours.These ranges were owing to the alternation of S. E. storms and N. W. winds.Taking the first range as a basis and allowing the height of the atmosphere to be 1,100 feet for the first inch, we have nearly 2,000 feet displaced during one day, if we look for the displacement near the earth, or some 30 or 35 miles, if we soar aloft in the upper regions to look for the lateral overflow of Professor Dove and about the same quantity restored the next. This brings us to the inquiry, how was it done?It is perfectly idle to talk about difference of temperature or tension of vapour, the ascent of warm air, or descent of cold in a case like this; or to say that they were occasioned by a lateral overflow of some thirty miles of its upper portion, first this way and then that, in such a brief space of time. The change is equal to nearly 1⁄15 of the weight of the whole atmosphere and the cause, whatever it was, existed within two or three miles of the earth. Mr. Redfield’s explanation I give in his own words, at length:“One of the most important deductions which may be drawn from the facts and explications which are now submitted, is an explanation of the causes which produce the fall of the barometer on the approach of a storm. This effect we ascribe to the centrifugal tendency or action, which pertains to all revolving, or rotary movements and which must operate with great energy and effect upon so extensive a mass of atmosphere as that which constitutes a storm. Let a cylindrical vessel, of any considerable magnitude, be partially filled with water and let the rotary motion be communicated to the fluid, by passing a rod repeatedly through its mass, in a circular course. In conducting this experiment, we shall find that the surface of the fluid immediately becomes depressed by the centrifugal action, except on its exterior portions, where, owing merely to the resistance, which is opposed by the sides of the vessel, it will rise above its natural level, the fluid exhibiting the character of a miniature vortex or whirlpool. Let this experiment be carefully repeated, by passing the propelling rod around the exterior of the fluid mass, in continued contact with the sides of the vessel, thus producing the whole rotary impulse, by an external force, analogous to that which we suppose to influence the gyration of storms and hurricanes and we shall still find a corresponding result, beautifully modified, however, by the quiescent properties of the fluid; for, instead of the deep and rapid vortex before exhibited, we shall have a concave depression of the surface, of great regularity: and, by the aid of a few suspended particles, may discover the increased degree of rotation, which becomes gradually imparted to the more central portions of the revolving fluid. The last-mentioned result obviates the objection, which, at the first view, might, perhaps, be considered as opposed to our main conclusion, grounded on the supposed equability of rotation, in both the interior and exterior portions of the revolving body, like that which pertains to a wheel, or other solid. It is most obvious, however, that all fluid masses are, in their gyrations, subject to a different law, as is exemplified in the foregoing experiment; and this difference, or departure from the law of solids, is doubtless greater in aëriform fluids than in those of a denser character.“The whole experiment serves to demonstrate that such an active gyration as we have ascribed to storms and have proved, as we deem, to appertain to some, at least, of the more violent class; must necessarily expand and spread out, by its centrifugal action, the stratum of atmosphere subject to its influence and which must, consequently, become flattened or depressed by this lateral movement, particularly toward the vortex or centre of the storm; lessening thereby the weight of the incumbent fluid and producing a consequent fall of the mercury in the barometric tube. This effect must increase, till the gravity of the circumjacent atmosphere, superadded to that of the storm itself, shall, by its counteracting effect, have produced an equilibrium in the two forces. Should there be no overlaying current in the higher regions, moving in a direction different from that which contains the storm, the rotary effect may, perhaps, be extended into the region of perpetual congelation, till the medium becomes too rare to receive its influence. But whatever may be the limit of this gyration, its effect must be to depress the cold stratum of the upper atmosphere, particularly toward the more central portions of the storm; and, by thus bringing it in contact with the humid stratum of the surface, to produce a permanent and continuous stratum of clouds, together with a copious supply of rain, or a deposition of congelated vapour, according to the state of the temperature prevailing in the lower region.”The italics in the foregoing extract are mine; and, in relation to it, I observe:1st. There is no cylindrical vessel around storms and air will not thus resist air. Confessedly, such resistance is necessary. Let any one watch his cigar smoke and see how readily it moves on, with little momentum. Let any one try the experiment of creating a whirl in the open air, or in a room, or box of paper, or other material, which can be suddenly removed, with air coloured by smoke. I am exceedingly mistaken if he does not find the presence of a “cylindrical vessel,” absolutely essential to prevent the instantaneous tangential escape of the air.2d. Turn back to page 3 and look at the fall of the barometer in the polar regions (recorded in the extract from Dr. Kane), with scarcely any wind and as little variation in its direction and see how utterly Mr. Redfield’s theory fails to account for the phenomena.3d. If I understand Mr. Redfield correctly, he has abandoned the claim as originally made, that the wind moves in circles, expanding and spreading out by a “lateral movement,” and now asserts that it blows spirally inward and elevates the air in the centre. I quote:“Vortical Inclination of the Storm Wind.; By this is meant some degree of involution from a true circular course. In the New England storm above referred to, this convergence of the surface-winds appeared equal to an average of about 6° from a circle. In the present case, such indication seems more or less apparent in the arrows on the storm figures of the several charts, where the concentrical circle afford us means for a just comparison of the general course of wind which is approximately shown by the several observations.“Perhaps we may estimate the average of the vorticose convergence, as observed in the entire storm for three successive days, at from 5° to 10°; out of the 90° which would be requisite for a congeries of centripetal or centre-blowing winds. This rough estimate of the degree of involution is founded only on a bird’s-eye view of the plotted observations. But, however estimated, this involution seems to afford a measure of the air and vapour which finds its way to a higher elevation by means of the vortical movement in the body of the storm.”If the elevation of the air at the borders of the storm and depression in the middle, resulted from the outward tendency and “lateral movement” of the revolving air and from the centrifugal force, as in the experiment with the water in a cylindrical vessel, as stated in the first paragraph quoted, an involution of from 5° to 10° from the action of a centripetal force, must carry the air inward and the barometer should stand highest in the middle of the storm. The change is fatal to his theory. The two are diametrically opposite in character and effect. In one, the superior strata would be brought down in the centre by the lateral pressure outward; in the other, they would be elevated by the involution, which “affords a measure of the air and vapour which finds its way to a higher elevation,” etc. It is perfectly obvious Mr. Redfield has refuted his own hypothesis.In doing this, he is met by the other difficulty alluded to, which he does not attempt to explain. This gathering of the air inward, spirally, by a centripetal force, if it took place, not only would not depress but must elevate the barometer in the centre, above that of the adjoining atmosphere.When he first attributed the depression of the barometer to a lateral movement and centrifugal force, he supposed the superior strata descended into the depression and their frigidity occasioned the condensation and cloud and rain. How he now proposes to account for the formation of cloud and rain during storms, while the warm air of the inferior stratum finds its way to a higher elevation in the centre of the storm, he does not inform us and we must wait his time.“I have,” he says, “long held the proper inquiry to be: “What are storms?” and not: “How are storms produced?” as has been well expressed by another. It is only when the former of these inquiries has been solved that we can enter advantageously upon the latter.”The former does not seem to be yet solved, or the solution of the latter commenced. Mr. Redfield tells us (page 259 and onward), that there is an extended stratum of stratus-cloud, which overlies the storm and that it does not differ greatly from one mile in height. We are not told how the air, which finds its way to a higher elevation during several days’ continuance of such a storm, gets through the stratum. If he is right it must do so and it would not answer to suppose a very small opening or gentle current through it, to carry off all the air -which works inward in a hurricane, during several days continuance. But he does not seem to recognize either the necessity or existence of any vent at all; nor is there any; and this fact is open to the observation of every school-boy in the country; and it is equally open to his observation that when and where the barometer is most depressed, the stratus storm-cloud is nearest the earth. Colonel Reid has much to say about the “storm’s eye,” or “treacherous centre” of a storm.A careful analysis of the instances where the “storm’s eye” is noticed will show that the term is applied, in the northern hemisphere, to that lighting up in the W. or N. W., which is the commencement of the clearing-off process and attended with a shift of wind to the fair-weather quarter: i. e., to W. or N. W. Just such an “eye” as is seen when the last of the storm cloud has passed so far to the east as to admit the rays of the sun under the western or north-western edge of it. The same kind of “storm’s eye” is described in the southern hemisphere, except that the wind shifts to S. W. instead of N. W., that being the clearing-off wind there. No instance of a “storm’s eye” in the centre of the extended stratum of stratus-cloud, which overlies the storm, can be found recorded, to my knowledge; and it is obvious that Colonel Reid adopts the view of Mr. Redfield, that the westerly and N. W. fair weather winds are a part of the storm. So long as these gentlemen hold to that opinion they will never solve the question, “what are storms?” or reach the other, “how are storms produced?”Notwithstanding, Mr. Redfield asserts, or adopts the assertion, that the inquiry should be, “What are storms?” not “How are storms produced?” that inquiry should be a rational one and should not violate all analogy, or call for an explanation which science cannot rationally furnish. Mr. Redfield does not seem to have formed any just conception of the immeasurable power of a hurricane, five hundred miles in diameter; or of the nature of that rod which the Almighty must insert in it, to whirl it with such violent and long-continued force; nor any just conception of the tendency of the whirling mass, in the absence of his “cylindrical vessel,” to fly off, tangentially, into the surrounding air; or of the nature or power of the centripetal force necessary to hold the gyratory mass in its current and gather it in involute spirals toward a centre.Nor has any other man who has witnessed, or read of mountain-tossed waves; of the largest ships blown down and engulfed; of towns submerged and vessels carried far inland and left in cultivated fields, by the subsidence of the sea; of sturdy forests and strongly-built edifices prostrated; or listened to the howling of the tempest and felt his own house rock beneath him, been able to conceive of any known form of calorific or mechanical, or other power, acting from a comparatively small centre, which could hold such an immense irresistible mass of whirling air in a circle and gather it in toward the centre in gradually contracting spirals. I confess that, to my mind, it seems little less than a mockery of our intelligence for Mr. Redfield, or Professor Dove, or any other man, however distinguished he may be, to tell us that all this is the result of a “tendency to left-wise rotation” of ordinary winds, “coming into each other,” or “over-sliding,” or “meeting,” or “encountering,” on this “front,” or that, down in Central America, or in the West Indies, or the monsoon region; or to talk of “lateral overflows” from mere gravity; of the ascent of warm air, or the descent of cold strata; of the resistance of adjacent passive air, or other mere atmospheric resistances in connection with such awful manifestations of power. Their explanations of these phenomena are not rational, nor can any rational man, who will bestow upon them half an hour of comprehensive, unbiased reflection, believe them.Waiving many minor points of great force, for this notice of Mr. Redfield’s theory is already too much extended for my limits, I am constrained to take issue with him on the fact and to assert, unhesitatingly, that in a majority of instances no such barometric curve exists.Doubtless the depression beneath the storm is found and extending the line into the usual fair weather elevation on each side may also have exterior lateral elevations, as Mr. Redfield is obliged to do, to get his supposed circle of winds at all. Doubtless, too, the seamen sailing out of a storm, on either side and approaching fair weather, will have a rising barometer. But from front to rear, on the line of progression, in tropical storms, the curve does not exist on shore, in this latitude, oftener than in two, or possibly three, cases in ten; and then only upon a single state of facts; that is, when there is an interposition of N. W. wind; and this, at some seasons, rarely occurs. An elevation usually occurs before the storm, on its front, if it present an extensive easterly front, as one of these classes does and a depression is left after it has passed off, unless a considerable body of N. W. wind interposes, as heretofore stated. But when there is not such interposition of N. W. wind (for W., W. N. W., or even N. W. by W. will not suffice), there is not an immediate rise of the barometer corresponding in rapidity and extent with the fall and frequently none during the first twenty-four hours of bright, fair weather. Let the reader, if he has access to a barometer, note this fact, for it is obvious and conclusive.Finally, there are other atmospheric conditions to which the barometric changes are obviously due:1st. The counter-trade is of a different volume, at different times, over the same locality and hence a difference in the normal elevations of the barometer.2d. It is at a different elevation, at different times, over the same locality. It was so found by the investigations of the Kew Observatory Committee referred to; has been so found by other aeronauts and may readily be seen by a careful, practiced observer.It is highest, with a high barometer, in serene weather, when a storm is not at hand; and can sometimes be plainly seen to ascend when a considerable volume of N. W. wind is blowing in beneath and elevating, simultaneously, the trade and the barometer.Opportunities occur every year, when the northern edge of the dissolving stratus-cloud is attenuated and the storm is clearing off in the N. W., with wind from that quarter and a rising barometer, when its gradual elevation may be observed to correspond with the volume of that wind.3d. During storms, with a low barometer, the trade and the clouds run low. This, too, is clearly observable, especially when the stratus-cloud passes off abruptly, very soon after the rain ceases. In such cases the barometer will remain depressed for a considerable time, unless another storm supervenes speedily, or the wind sets in from the N. W.4th. The trade, in a stormy state, moves faster than when in a normal condition. This is observable during the partial breaks, which frequently occur in storms and at other times. It is also inferable from the more rapid progress of the more intense centre and other intense portions of storms and the consequent greater depression of the barometer, under such centres or intense portions. (See the storm of Professor Loomis.) It is obvious, also, from the greater rapidity of progress attending the more intense and violent storms which all investigations discloses.These simple facts explain all the phenomena:1st. The trade stratum is a continuous unbroken sheet and its descent must displace a portion of the surface atmosphere. A portion of it is impelled forward, aiding in the precedent elevation of the barometer and a portion is attracted backward, into the space from which a like portion had been previously attracted by the passing storm cloud, forming the easterly wind.2d. The increased progress of the stormy portion of the counter-trade occasions an accumulation in front of the storm and an elevation of the barometer and tends also to increase the depression under the spot from which it moves. The thin sheets of surface wind, which are drawn in under the stratus from the sides, to some extent, counteract the latter. That which is drawn from the front in successive portions, fills the space from which like portions had been drawn to the westward and left behind in a passive state by the passing storm. Thus, the surface atmosphere of New England may pass under the entire width of a storm, as a gale; moving now in puffs with great violence, as it passes beneath irregular and intense portions of the cloud and now moderately; and be left, in a passive state, in Kentucky, occupying the space from which the atmosphere had been previously drawn by the same storm, in like manner, on to northern Texas.3d. The nearer the stratus-cloud to the earth, the greater the displacement of surface atmosphere, the lower the barometer, and, ordinarily, the more violent the wind. First, because the same intensity, which, by attraction, brings the trade near the earth, acts with greater force upon the surface atmosphere; and, secondly, the storm winds, which are often most rapid beneath the clouds and above the earth, are likely to be felt with more violence at its surface, where the stratus cloud runs low, especially at sea.I desire to commend all these facts, in relation to the theory of Mr. Redfield, to the careful attention and observation of those who, although believers in the theory, are not wedded to it; and who have a sincere desire to understand the phenomena which are continually and thus far, mysteriously, occurring within two or three miles of us, while our knowledge of the distant worlds around us; the science of astronomy; seems almost perfect.I will return to a further and a careful consideration of the nature of the reciprocal action between the earth and the counter-trade and the facts bearing upon the question, in another chapter. It is obvious that received theories cannot aid us materially in the inquiry.
Three theories have been advanced by meteorologists of this country, two of which profess to explain all the phenomena of the weather. Professor Espy attributed the production of storms and rain to an ascending column of air, rarefied by heat and the rarefaction increased by the latent heat of vapour given out during condensation and an inward tendency of the air, from all directions, toward the ascending vortex, constituting the prevailing winds. Thus, Professor Espy conceived and to some extent proved, that the wind blew inward, from all sides, toward the centre of a storm, either as a circle, or having a long central line and he conceived that it ascended in the middle and spread out above; and that clouds, rain, hail and snow, were formed by condensation consequent upon the expansion and cooling of the atmosphere, as it attained an increased elevation.This ascent was not, in fact, proved by Professor Espy, has not been found by others and is not discoverable, according to my observations. The theory was ingenious, founded on the theory of Dalton, that the vapour was maintained in the atmosphere by reason of a large quantity of latent heat, which was given out when condensation took place. This theory is also unsound. No such elevation of temperature is found in clouds or fogs when they form near the earth, however dense. Thus the two principal elements of Professor Espy’s theory are found to be untrue and the theory untenable. But it was sustained with great ability and research and the distinguished theorist deserves much for the discovery and record of important facts in relation to the weather. Aside from its theoretical views, his book contains a great mass of valuable information and will well repay the cost of purchase and perusal.Another theory, by Mr. Bassnett, is of recent date, founded on the influence of the moon and the supposed creation of vortices in the ether above, whose influence extends to the earth, producing storms and other phenomena. No one can peruse his book without conceding to him great ability and scientific attainment; and if his theory was true, the periods of fair and foul weather could be calculated with great mathematical certainty. But it contains inherent and insuperable objections. I will only add that all herein before contained is in direct opposition to it.Mr. W. C. Redfield, of New York, as early as 1831, first advanced in this country the theory of gyration in storms and investigated their lines of progress on our coast and continent. His theory is limited in its character and does not profess, except indirectly, to explain all, or indeed any, of the other phenomena of the weather. As far as it goes, however, it is generally received in this country and Europe and has been adopted by Reed, Piddington and others, who have written on the law of storms. The position of Mr. Redfield is honorable to himself and his country. Science and navigation are much indebted to him for his industry in the collection of facts. Nevertheless, his theory is not in accordance with my observation and I deem it unsound. Although expressed disbelief of the theory has been characterized as an “attack” upon its author, I propose, with that respect, which is due to him but with that freedom and independence, which a search for truth warrants, to examine it with some particularity. It is a part of the subject and I cannot avoid it.When the theory was first announced, I adopted it as probably true; and being then engaged in a different profession, which took me much into the open air by night and day, I watched with renewed care the clouds and currents for evidence to confirm it. I discovered none; on the contrary, I found much, very much, absolutely and utterly inconsistent with its truth. The substance only of these observations will be adduced.Mr. Redfield admits that the progression of our storms in the vicinity of New York, is from some point between S. S. W. and W. S. W., to some point between N. N. E. and E. N. E. According to my observation, except perhaps in occasional autumnal gales, they are not often, if ever, from S. of S. W. and the great majority of them, including, I believe, all N. E. storms, are between S. W. and W. S. W. Now, the card of Mr. Redfield, moving over any place from any point between S. W. and W. S. W., calls for a S. E. wind at its axis, an E. wind at its north front and a S. wind at its south front and does not call for a N. E. wind on its front at all, except at the north extreme, where it could not continue for any considerable period.In relation to this, I observe, 1st. About one-half of our N. E. storms, including some of the most severe ones, not only set in N. E. but continue in that quarter without veering at all, during the entire period that the storm cloud is over us; usually for twenty-four hours; not infrequently for forty-eight hours, sometimes for seventy-two or more hours. This everyone can observe for himself and it can not, of course, be reconciled with his theory.2d. N. E. storms, whether they set in from that quarter in the commencement, or veer to it afterward, when they do “change” round, more frequently veer by the S. to the S. W. in clearing off, than back through the N. into the N. W. The former, in accordance with his theory, they cannot do, as the reader can see by passing the left side of the card over his place of residence on the map from S. W. to N. E.3d. N. E. storms often pass off without hauling by S. or backing by N. and with or without a clearing off shower, the wind shifting and coming out suddenly at S. W. This they could not do in accordance with his theory, as slipping the card will show.4th. From June to February it is exceedingly uncommon for a N. E. storm to back into the N. W. They do so more frequently from February to May, especially about the time of the vernal equinox and after; and then, because the focus of precipitation and storm intensity of the extra tropical zone of rains is S. of 42° east of the Alleghenies. His theory requires them to back by N. into N. W. in all cases, when they set in N. E.5th. When they do back from the N. E. into the N. W., it rarely indeed continues to storm after the wind leaves the point of N. E. by N. and generally, if it does continue stormy, the wind is light and not a gale, however violent the gale from the eastward may have been. Usually, by the time the wind gets N. W., it has cleared off. This, Mr. Redfield, as we shall see, evades by embracing the N. W. fair wind as a part of the same gale. According to my observation, therefore, a very large proportion of the N. E. storms and they are a majority of the most violent ones of our climate east of the Alleghenies, do not commence, continue, or veer in accordance with his theory but the reverse; and so long as this is so, I cannot receive his theory as true.6th. S. E. storms do not always, or indeed often, conform to the requirements of his card. When they set in violently at S. E. and continue so for hours without veering, the axis of the storm should be over us and the wind should change suddenly to N. W. This did not occur in the storm of Sept. 3, 1821, nor does it often, if ever, occur in the summer or early gales of the autumnal months. In the later storms of autumn and as often in those which are very gentle as any and in the winter months when S. E. gales are rare, it does sometimes so change after the storm cloud has passed. But in the winter months, as in the storm investigated by Professor Loomis, the storms are frequently long from S. E. to N. W. and the S. E. wind blows nearly in coincidence with its long axis, for a thousand or fifteen hundred miles, till the barometric minimum is passed and the inducing and attracting force of this part of the storm cloud is spent and then the N. W. wind follows; sometimes blowing in under the storm cloud, turning the rain to snow; but oftener following the storm within a few hours, or the next day. The storm of Professor Loomis, when over Texas, was not probably more than four or five hundred miles in length. As it curved more and passed north and east, it extended laterally, its centre travelling with most rapidity and when it reached the eastern coast was about fifteen hundred miles long and not more than six hundred broad. Along the eastern part of that storm, except when by its more rapid progress the front projected much further eastward over New England than its previously existing line, the S. E. winds blew. When it bulged out, so to speak, by reason of the increased progress of the centre, the wind veered to the N. E. The centre of the storm passed near St. Louis and south of Quebec, as the fall of rain, the bulging of the rapidly-moving centre and the line of subsequent cold, attest. It is utterly impossible for any unbiased mind to look at the description of that storm and attribute to it a rotary character. With all the data before him, Mr. Redfield himself has not attempted it directly.[8]The September storm of 1821 was more violent in character than any which have since occurred. My recollection of it is as distinct as if it occurred yesterday. Peculiar circumstances, not important in this connection, fixed my attention upon the weather during that day and night. There were cirro-stratus clouds passing all day, from about S. W. to N. E., thickening toward night with fresh S. S. W. wind and flocculent scud, such as I have since seen at the setting-in of S. E. autumnal gales. In the evening the wind (in the immediate neighbourhood of Hartford, Ct.), veered to S. E., the cloud floated low, it became very dark and the wind blew a most violent gale. The trees were falling about the house where I then resided, the windows were burst in and I was up and observant. When the cloud passed off to the east, it was suddenly light and almost calm. The western edge of the storm cloud was as perpendicular as a steep mountain side and was enormously elevated and very black. I have sometimes seen the western side of a summer thunder cloud, which had drawn a violent gust along beneath it, as elevated and perpendicular but never a storm cloud. No cloud of that depth, or intensity as exhibited by its peculiar blackness, ever floated or will float so near the earth, without inducing a devastating current beneath. After it had passed the ridges east of the Connecticut valley, its top could be seen for a long and unusual period over the elevated ranges.Now that storm was but an intense portion of an extensive stratus-rain cloud. Such portions frequently exist and Mr. Redfield admits the fact. Another like portion, in the same storm, passed over Norfolk, Virginia and the adjacent section, where the wind was N. E. and veered round by N. W. to S. W. Baltimore and some vessels at sea, were between the two intense portions of the storm and were not affected by either. Its northern limit was bounded by a line, drawn from some point not far north of Trenton, New Jersey, north-eastward and north of Worcester, Massachusetts. I was about forty miles south of its northern limit and north of its centre. During that day and the next, there was wind from S. W. to S. E., inclusive, including the gale and from no other quarter. It did not at any time veer to the W. or N. W. After the passage of the storm-cloud, the wind was very light. When this intense portion of the storm passed over the valley of the Connecticut, its longest axis was from S. S. E. to N. N. W. and the wind was S. E. the whole length of it. In its passage from the longitude of Trenton to Boston, there was N. W. wind at one point and but one and that was in the iron region, at the N. W. corner of Connecticut, at the northern limit of the intense cloud and owing, doubtless, to some local cause. The direction of the wind in that storm was in accordance with what is generally true of our storms. The wind on the front of the storm depends upon its shape. If the storm is long in proportion to its width (and no other violent autumnal or winter storm has been investigated, to my knowledge), the wind blows axially, or obliquely, on its front. Thus, if long from S. E. to N. W., the wind on its front will blow from the S. E. So, if the storm is long from S. W. to N. E. and has a south-eastern lateral extension, with an easterly progression, the wind will blow axially in the centre and obliquely at the edges. Instances might be multiplied but I refer to one of recent date and striking character. All of us remember the drought of 1854. It ended in drenching rain on the 9th of September. This rain fell from a belt, half showery and half stormy in character, which had a S. E. lateral extension.The evening of the previous day there was some lightning visible at the north and the usual S. S. W. afternoon wind continued fresh after nightfall. The next day we had a brisk wind from the same quarter, and, after noon, the clouds appeared to pile up in the far north, seeming very elevated. They continued to do so, extending southerly during the afternoon, with a high wind from S. S. W., the cumulus clouds moving E. N. E. At 5 P.M., gentlemen who left New York at 3 P.M., reported that a dispatch had been received from Albany, dated 1 P.M., stating that it was raining very heavily there. About 7 P.M., the belt reached us and it rained heavily from that time till morning. Not far from 8 P.M. and during the heaviest rain, the wind shifted from the S. S. W. to N. E. and blew fresh and cold from that quarter during the night and till the belt had passed south and then from N. E. by N., cool, with heavy scud, during the forenoon, veering gradually to the N. N. E. and dying away. After the rain ceased, the northern edge of the belt was distinctly visible in the S. and S. E., its stratus-cloud moving E. N. E. and its scud to the westward.The front of that storm did not pass over us. It was long and narrow. The wind blew somewhat obliquely inward, along its southern border, to the eastward, and, in like manner, to the westward, on its northern border but from the N. E. axially along its central portions.In the last instance, the wind changed from S. W. to N. E. This, too, is impossible, according to Mr. Redfield’s theory. Similar instances, in summer and early autumn, are not uncommon. But I shall recur to this in connection with the different classes of storms.Again, the manner in which these S. E. winds co-exist with the N. E. and become the prevailing wind, toward the close of the storm, is instructive and inconsistent with the theory of Mr. Redfield. In the West Indies, the first effect of the storm is to increase the N. E. trade; the wind then becomes baffling but settles in the N. W. or N. N. W., in direct opposition to the admitted progress of the storm. At this point, or at S. W., it blows with most force. Sometimes it veers gradually and sometimes falls calm and comes out from the S. W., blowing violently. It ends by veering to the S. E., following gently the course of the storm. Thus, Mr. Edwards, in the third volume of his History of Jamaica, as herein before cited, “all hurricanes begin from the north, veer back to W. N. W., W. and S. S. W. and when they get round to S. E. the foul weather breaks up.”A short, sudden gale, resembling those of our summer thunder-showers, is sometimes met with from the S. E.; but the violent hurricanes of any considerable continuance are, in almost every case, as just stated.Now, there is, in our latitudes, an obvious law on the subject and it is this; If the storm is not disproportionately long, northerly and southerly, there is a general tendency to induce and attract a surface current, in opposition to the course of the storm on its front and especially its north front. At the same time, there is a tendency to induce a lateral current on its side, particularly the southerly side and sometimes its south front: that the latter current is, in the first part of the storm, above the former; in the middle and latter part, it becomes the prevailing current at the surface and the wind changes accordingly, with or without a calm; that this lateral change sometimes takes place on either side but usually occurs on the side where the water is warmest, or there is, for other and local reasons, a greater susceptibility in the atmosphere to inductive and attractive influence. Thus, our N. E. storms very frequently have a southerly current also, drawn from the ocean, south of us, which forms the middle current, and, in the middle and latter part of it, becomes the prevailing one. I have seen more than a hundred such instances, clearly and distinctly marked. Since I have been writing this chapter, January 29th, 1855, such an instance has occurred. On Sunday, the 28th, the cirro-stratus were all day passing from the S. W. to N. E. and gradually thickening with light air from the E. N. E., in the afternoon. During the evening the wind set in violently from the N. E., with a deluging rain. During the night and after a brief calm, it changed suddenly to the southward and blew in like manner. This morning the storm was gone and with it, six inches of hard, frozen icy snow; the trade was clear, with the exception of here and there a broken, melting piece of stratus but scud were still running from the southward and the wind has been from the south, veering to S. W., all day, with sunshine. As I have before remarked, this middle current is always present, in this locality, in stratus storms, when there is a heavy fall of rain or snow, although, when the latter happens, the middle current is sometimes from the northward; if it be from the southward, it turns the snow first into very large flakes and then to rain in our part of the storm.Doubtless, the same thing occurs everywhere. In the West Indies and especially over the Leeward Islands, the middle current is most commonly from the stream of warm water which runs off to the westward into the Caribbean Sea; as the S. W. moonsoon is from the same current below the Cape de Verdes. The S. W. winds, which come from those south polar waters, in the West Indies, appear to be the most violent. But it may be on either or both sides.The hurricane cloud of the West Indies moves confessedly N. W. in most instances and undoubtedly it does in all. There is an immutable law that requires it. The seeming exceptions are not such; they are but instances imperfectly investigated. Now, a circular storm moving N. W. can set in N. W. only on the left front and cannot change to S. W. on that side of the axis. Nor can the wind blow at the axis from N. W. at all. It should be N. E. in first half and S. W. in last half. Strange as it may seem, the axis of a West India hurricane in conformity with Mr. Redfield’s theory and a N. W. progression, has never been found, with perhaps a single exception, in any one of which I have seen a description. On the west coast of Europe, the gale is commonly from the Atlantic, either following under the storm from the S. W., or blowing in diagonally from the W. or N. W.; the N. E. wind of western Europe being a cold, dry wind, which there is reason to believe has been around the Siberian pole and is returning, as the cold northerly winds of the North Pacific have around the North American magnetic pole. “If the N. E. winds always prevailed,” says Kämtz, speaking of Berlin, “even at a considerable height it would never rain.” This was based on an observation of showers and not fully reliable. But the dry and cool character of the N. E. wind of western Europe is unquestionable. The S. E. wind is also a storm wind but owing to the character of the surface from which it is attracted, it is not as violent as the westerly winds are.Such, too, is the general course and character of the side wind in the southern hemisphere. There gales are less frequent, the magnetic intensity is less, the counter-trades are less; it is not in “the order of Providence” that as much rain shall fall there. Nevertheless, gales occur, although rarely, if ever, with equal violence. About New Holland, where storms are pursuing a S. E. course, they have the wind N. E., corresponding to our S. E., veering from thence, by the north, to the westward, clearing off from S. W., with a rising barometer, as ours do from N. W.In the Bay of Bengal, the Indian Ocean and the Arabian Sea, there is more irregularity.But the law of progress and lateral winds can be distinctly traced as present and prevailing, notwithstanding the irregularities. Our limits do not permit an analysis. In the celebrated case of the Charles Heddle, there was much evidence to show that she was driven across the front of the storm by one lateral wind and back by another. (Diagram of Colonel Reid, p. 206.)The waters of the Indian Ocean are hot and confined. Storms there are often composed of detached masses, move slower; sometimes not more than three or four miles an hour; and they curve over the ocean, where it is hotter than in any similar latitude. Yet, notwithstanding all peculiarities and irregularities, the law we have been considering is probably the prevailing law there.No man knows better the existence of these different currents than Mr. Redfield. Doubtless it has escaped his attention that the upper of two, after the passage of a considerable proportion of the storm, becomes the lower and causes a seeming change of the same wind.In a series of elaborate articles, substantially reviewing the whole subject, published in the American Journal of Science, for 1846, he says:“In nearly all great storms which are accompanied with rain, there appear two distinct classes of clouds, one of which, comprising the storm scuds in the active portion of the gale, has already been noticed. Above this is an extended stratum of stratus cloud, which is found moving with the general or local current of the lower atmosphere which overlies the storm. It covers not only the area of rain but often extends greatly beyond this limit, over a part of the dry portion of the storm, partly in a broken or detached state. This stratus cloud is often concealed from view by the nimbus and scud clouds in the rainy portion of the storm but by careful observations, may be sufficiently noticed to determine the general uniformity of its specific course, and, approximately, its general elevation.“The more usual course of this extended cloud stratum, in the United States, is from some point in the horizon between S. S. W. and W. S. W. Its course and velocity do not appear influenced in any perceptible degree by the activity or direction of the storm-wind which prevails beneath it. On the posterior or dry side of the gale, it often disappears before the arrival of the newly condensed cumuli and cumulo-stratus which not infrequently float in the colder winds, on this side of the gale.”“The general height of the great stratus cloud which covers a storm, in those parts of the United States which are near the Atlantic, cannot differ greatly from one mile; and perhaps is oftener below than above this elevation. This estimate, which is founded on much observation and comparison, appears to comprise, at the least, the limit or thickness of the proper storm-wind, which constitutes the revolving gale.“It is not supposed, however, that this disk-like stratum of revolving wind is of equal height or thickness throughout its extent, nor that it always reaches near to the main canopy of stratus cloud. It is probably higher in the more central portions of the gale than near its borders, in the low latitudes, than in the higher and may thin out entirely at the extremes, except in those directions where it coincides with an ordinary current. Moreover, in large portions of its area, there may be and often is, more than one storm-wind overlying another and severally pertaining to contiguous storms. In the present case, we see, from the observations of Professor Snell and Mr. Herrick, at Amherst, Massachusetts and at Hamden, Maine (115 and 135 b.), that the true storm wind, at those places, was super-imposed on another wind; and various facts and observations may be adduced to show that brisk winds, of great horizontal extent, are often limited, vertically to a very thin sheet or stratum.”Much of the foregoing is graphically described and unquestionably true. But it may well be asked how he, or others, distinguish which of two or more currents (for there are frequently three and sometimes four visible), are the true currents of the storm and which interlopers from another storm?Is the true one always the upper one and why?If the upper one, why is the interloper at the surface noted and quoted to prove what a storm is?How does he know what proportions of the winds he has recorded to show the revolving motion of gales, were the true storm winds of the particular storm?or, that every one of them was not an interloping wind on which the true storm wind was superimposed?These inquiries are pertinent, for obviously, unless some rule for distinguishing between the currents is given and there be evidence of direct observation to show that the surface wind, whose direction is noted, is the true wind of the storm and that the latter is not superimposed, no reliance can be placed upon logs, or newspaper accounts, or registers. There is another element besides direction, viz.: superimposition, a determination of which is essential to truth. It will be difficult for Mr. Redfield to say that a determination of that element has been made, with certainty, in a single storm he has investigated; and in relation to the convergence of storms and blending and superimposition of their winds, I think he is mistaken.Mr. Redfield is right in saying (American Journal of Science, vol. ii., new series, p. 321) that “too much reliance may be placed upon mere observations of the surface winds in meteorological inquiries,” and yet they only have thus far been regarded and he has proved gyration in no other way. I have frequently, with a vane in sight, asked intelligent men how the wind was and been amused and instructed by their inability to state it correctly. Mr. Redfield, in his inquiries, often found two reports of the weather at the same time, from the same place, materially different; and I have known, from my own observation, newspapers and meteorological registers to be several points out of the way; and this, because the vanes are influenced by local elevations and change several points and very often; because few know the exact points of the compass in their own localities and because entire accuracy has not been deemed essential. For these reasons, newspaper and telegraphic reports are not always reliable; and therefore and because, also, storm-winds are easterly and fair winds westerly and the former veer from east around to west, on one or both sides in many cases, there are few storms which cannot be represented as whirlwinds, by a proper selection of reports, a corresponding location of the centre and an extension of the lines of supposed gyration, so as to include the preceding winds, the actual winds of the storm and the lateral and succeeding fair weather ones.But, again, Mr. Redfield is right in saying there is, in such cases, “an extended stratum of stratus cloud,” and it is always present. But why does he say this covers the storm?Is it distinct from it and if so, what is it doing there?What power placed it there and for what purpose?Has this extended stratum of cloud, which forms the canopy of a vast chamber; five hundred to one thousand miles in diameter and less than two miles in vertical depth, while the earth forms the floor; any agency in producing the whirl that is supposed to be going on within it and if so, what?Has the earth any agency and if so, what?If neither the ceiling nor floor of the chamber have any agency in producing it, what does?Are we to consider the storm-scud as possessing the power and as waltzing around the aerial chamber, carrying the air with them in a hurricane-dance of devastation?What, in short, is the power and how is it exerted?To these questions, Mr. Redfield’s essays furnish no comprehensive answer. There is an intimation that the cause of storms will be, at some future day, developed. One attempt and but one, has thus far been made and that I quote entire:“We have seen that the two Cuba storms, as well as the Mexican northers, have appeared to come from the contiguous border of the Pacific Ocean.“Now, are there any peculiarities in the winds and aerial currents of those regions, which may serve to induce or support a leftwise rotation in extensive portions of the lower atmosphere, while moving on, or near the earth’s surface?I apprehend there are such peculiarities, which have an extensive, constant and powerful influence. First, we find on the eastern portion of the Pacific, from upper California to near the Bay of Panama, an almost constant prevalence of north-westerly winds at the earth’s surface. Next, we have an equally constant wind from the southern and south-western quarter, which, having swept the western coast of South America, extends across the equator to the vicinity of Panama, thus meeting and commonly over-sliding the above-mentioned westerly winds and tending to a deflection or rotation of the same, from right to left. As this influence may thus become extended to the Caribbean or Honduras Sea, we have, next, the upper or S. E. trade of this sea, which is here frequently a surface-wind and must tend to aid and quicken the gyrative movement, ascribed to the two previous winds; and lastly we have the N. E. or lower trade, from the tropic, which, coinciding with the northern front of the gyration, serves still further to promote the revolving movement which may thus result from the partial coalescence of these great winds of Central America and the contiguous seas.“Thus, while a great storm is, in part, on the Pacific Ocean, its N. E. wind may be felt in great force on that side of the continent, through the great gorges or depressions near the bays of Papagayo or Tehuantepec, as noticed by Humboldt, Captain Basil Hall and others, the elevations which there separate the two seas being but inconsiderable; and, when the gyration is once perfected, the whole mass will gradually assume the movement of the predominant current, which is generally the higher one and will move off with it, integrally, as we see in the cases of the vortices, which are successively found in particular portions of a stream, where subject to disturbing influences.”The analogy between this and the theory of Professor Dove, cited above and prior, in point of time, is obvious. They are substantially alike in principle, with different locations. They differ also in this, Professor Dove appears to think something more than over-sliding necessary and assigns the duty of crowding the upper current down in to the lower, to make an encounter, to a lateral overflow from Africa. Mr. Redfield seems to think there may be a tendency to deflection when they “over-slide” each other. They are both closet hypotheses, the poetry of meteorology, with something more than poetical license as to facts.In the first place, no such concurring winds exist in the same locality at the same time. When the inter-tropical belt of rains is over Central America and Southern Mexico, a S. W. monsoon blows in under it but it usurps the place of all other surface winds; and, when the belt is absent, that portion of the eastern Pacific is most remarkably calm, or is covered by the N. E. trades. Secondly, the trade-winds everywhere pursue their appointed course without “tendency to deflection” by the meeting, or “over-sliding,” or “breaking in,” or “encounter,” of other winds. The great laws of circulation do not admit of any such confusion. And, lastly, no storm ever came over the eastern United States from that quarter. The unchangeable laws of atmospheric circulation forbid it. Recent observations also have shown that the storms on the west coast of Central America and the eastern Pacific, pursue a N. W. course, precisely as in the West Indies and everywhere over the surface-trades of the northern hemisphere. Indeed Mr. Redfield himself has recently investigated several of them and admits their course to be north-westerly. (See American Journal of Science, new series, vol. xviii. p. 181.)But, suppose the co-existence of the winds and the course of the storms admitted as claimed, let us seek for clearer views. What do these gentlemen mean?Do they intend to have us believe the air has inherent moving power and that the “tendency” of which they speak is an attribute of the winds and that when they thus meet and “come into each other,” “encounter,” or “over-slide,” and become acquainted, they wheel into a waltz and move off northward, “integrally,” with unceasing circular movement, even until they arrive at the Arctic circle?Or is it a mere mechanical effect of meeting, “coming into each other,” or “over-sliding?” If the latter, why a tendency to rotation from right to left?The trade-winds, at least, are continuous, unbroken sheets and not disconnected portions which meet and blow past each other and there is no warrant for placing them side and side and attributing to them any such mechanical effect and as little respecting the other winds. Outside of the fanciful hypothesis, there are no facts to show such a tendency one way rather than the other; and, in accordance with the known facts regarding stratification of the currents of air, no such “tendency” can exist.But what power impels the winds, which thus meet at these points?If they be impelled, is it consistent with the action of this power that the winds it has created and controls, should thus assume an opposite “tendency,” and whirl away to the north-eastward, regardless of the power that originated and controls them?What must this “tendency” be, which thus occasionally not only diverts the winds from the usually regular course given them by their originating power but increases their action, from gentle, ordinary winds, to hurricanes?Nay, which gives them a new, resistless gyratory and electric energy, increasing as the new, independent, supposed cyclonic organization moves off, “integrally,” away from “the home of its many fathers,” on a devastating journey towards the north pole?And, further, if all this were true as to the West Indies and Central America, what is to be said of the billions of other storms, originating on a thousand other portions of the earth’s surface and how are they to be accounted for, inasmuch as such other “meetings,” “coming into each other,” and “over-sliding,” and “tendency to deflection,” is not assumed to exist?These questions cannot be satisfactorily answered. The distinguished theorists are mistaken. The stratus-cloud does not over-lie or cover the storm. It is the storm. The winds beneath, whether surface or superimposed, are but its incidents, due to its static induction and attraction. Their direction depends on the shape of the storm cloud and its course of progression and the susceptibility of the surface atmosphere in this direction or that, to its inductive and attractive influence. Their force to its depth, its contiguity to the earth and the intensity of its action; and the scud, are but patches of condensation, occasioned by the same inductive action which affects and attracts the surface current in which they form.Another objection to Mr. Redfield’s theory of gyration is based upon the fact that in order to constitute his storm, to get the gyration, he has to include, at least, an equal amount, generally a great deal more, of fair weather. The N. W. wind, the “posterior, or dry side of the gale,” as he calls it (in the foregoing extract), is a fair weather wind. It is necessary, however, to complete the supposed circle and it is pressed into the service. The practical answer given to the question, “what are storms?” is, they are cyclones, part storm, so called and part fair weather; that is, the stratus-cloud, the scud, the easterly wind and rain or snow of day before yesterday, were the wet side, or front part of the storm and the sunshine, clear sky and N. W. wind of yesterday, to-day, and, perhaps, to-morrow, are the posterior or dry side. When a storm clears off from the N. W. it is not over, it is, perhaps, just begun; and, inasmuch as it storms again, very soon after the wind changes back from the N. W. to the southward, in winter, our weather then is pretty much all storms.The statement of this claim seems so absurd that it may appear like injustice to make it. But gyration cannot be made out without it and it is evident in the extract quoted above; in the claim that the winter northers of the Mexican Gulf are parts of passing storms; and clearly and unequivocally advanced as a distinct proposition, as follows:“1. The body of the gale usually comprises an area of rain or foul weather, together with another, and, perhaps equal, or greater, area of fair or bright weather.” (Am. Jour. of Science, vol. xlii. p. 114.)Now, in the first place, we must distinguish between a storm and fair weather, before we can tell what the former is and it is difficult to assent to a theory which explains what a S. E. storm of twelve hours’ continuance is, by including two or three days of succeeding N. W. fair weather wind, as a part of it. There is no proportionate relation as to time, nor any relation as to qualities, or the attending conditions of the atmosphere, nor any conceivable connection, except the hypothetical one of gyration, between the two winds.And, in the second place, it is true and Mr. Redfield is well aware of the fact, that winds often blow for many days from the N. E., S. W., or N. W., without any preceding or succeeding winds to which they have any discoverable relation. If, therefore, truth would justify Mr. Redfield in including the fair weather wind, a difficulty would remain which his theory does not cover or explain.No American, except Mr. Redfield, has been able to discover satisfactory evidence of the gyration of storms, by actual careful observation, or a careful unbiased collation of the observation of others. Professor Coffin is reported to have read to the Scientific Association, at their Buffalo meeting, a paper, confirmatory, in part but I have not been able to see it. The tracks of tornadoes have been searched as with candles. When they have been narrow, from forty to eighty rods, their action has been substantially similar, and, although, as we have herein before stated, some irregularities have been found which were consistent with gyration; for irregularities attend the violent action of all forces and particularly the motion of electricity through the atmosphere, as every one who has seen the zig-zag course of a flash of lightning knows; yet the evidence of two lateral inward currents, or lines of force, has predominated over all others. In all cases, where the path is narrow, those lateral currents are the actors; they constitute the tornado; their irregularities of action produce the exceptions; but the exceptions are neither numerous nor uniform and do not prove either the theory of Mr. Espy or that of Mr. Redfield. The action is not that of moving air, merely but of a power exceeding in force that of powder, which nothing but electricity or magnetism can exert. As the path widens, the wind becomes more like the straight-line gust which follows beneath the ordinary severe thunder-showers. His theory finds no substantial confirmation or support in the path of the tornado.Several storms were investigated by Professor Espy, some of them the same which Mr. Redfield had attempted to show were of a rotary character; one or two by the Franklin Institute of Philadelphia; one by Professor Loomis, already alluded to; and recently, two by Lieutenant Porter, from logs returned to the National Observatory. None of these investigations confirm the theory of Mr. Redfield. Indeed, Mr. Redfield himself has found it necessary to resort to suppositions of modifying causes to explain the evident inconsistencies. It is assumed that the axis, or centre, oscillates and describes a series of circles; and thus, one class of difficulties is avoided. Again, it is assumed that simultaneous storms converge and blend upon the same field and another class of difficulties are surmounted. And, again, inasmuch as it is notorious that violent gales are rarely if ever felt with equal violence around the area of a circle but from one or two points only, it is assumed, that the storm winds ascend, superimpose and descend again, when they return to the place of their first violent action, etc. The simple truth requires no such resort to modifying hypothesis.Still, another objection is, that the changes in the barometer, which occur before, during and after storms, do not sustain the claims of Mr. Redfield or the requirements of his theory.The barometer sometimes rises before storms. It generally commences falling about the time, or soon after the storm sets in, continues to fall during its progress and rises again, sooner or later, afterward. This is the general rule.On this subject Mr. Redfield’s claim is this:“Effect of the Gale’s Rotation on the Barometer.; The extraordinary fall of the mercury in the barometer, which takes place in gales or tempests, has attracted attention since the earliest use of this instrument by meteorologists. But I am not aware that the principal cause of this depression had ever been pointed out, previously to my first publication in this journal, in April, 1831, when I took the occasion to notice this result as being obviously due to the centrifugal force of the revolving motion found in the body of the storm.“Since that period, inquiries have been continued by meteorologists in regard to the periodical and other fluctuations of the barometer and the relations of these fluctuations to temperature and aqueous vapour. But these incidental causes of variation, in the atmospheric pressure, prove to be of minor influence and we are left to the sufficient and only satisfactory solution of this marked phenomenon which is found in the centrifugal force of rotation.”The average pressure of the atmosphere, at the surface of the ocean, or in the interior of the country, allowing for elevation, is about equal to the weight of a column of quicksilver, thirty inches in height; hence the barometer is said to stand at about thirty inches at the level of the sea.[This is the first time I have looked at a tape measure to realise that a column of 30 inches is only 762 millibars. I can’t help thinking that that is quite a low pressure compared to everything I have ever seen on a sea level chart. A pressure as low as 850 millibars (851mb = 33 ½”) is too low for me to recall from any of my memories. I believe that such things may have happened once or twice in some very nasty tropical storms. What I had considered as the average sea level pressure of 1016 millibars turns out to be 40 inches.Even a man who can’t count could be expected to realise this discrepancy before now. Especially when his trade requires him to arm himself with a tape-measure for 8 hours a day, 5 days a week.]This is sufficiently accurate for the northern hemisphere, north of the N. E. trades; but the average is somewhat lower in the trades and in the southern hemisphere. Thus, the average of sixteen months, during which the Grinnell expedition was absent, was 30.08⁄100.
CHAPTER IX.Before proceeding to do this, however, it may be well to look at some theories which have been advanced and to a greater or less extent adopted and at their bearing upon the question.The calorific theory is at present the prevailing one in Europe and in this country. Meteorologists there and here refer all atmospheric conditions and phenomena to the influence of heat. The principal applications of that theory have been considered. But within the last few years the elasticity and tension of the aqueous vapour of the atmosphere have received much attention, as exerting an auxiliary or modifying influence. Professor Dove, of Berlin, who ranks perhaps as the most distinguished meteorologist of that continent, attributes barometric variations to lateral overflows, and, in the upper regions, resulting from the elevation of the atmosphere by expansion; and in this view meteorologists of Europe seem generally to acquiesce. In an article sent to Colonel Sabine and recently republished in the American Journal of Science, January, 1855, in thus attempting to account for the annual variation of barometric pressure, which occurs in Europe and Asia, and, indeed, over the entire hemisphere. He says:“From the combined action or the variations of aqueous vapour and of the dry air, we derive immediately the periodical variations of the whole atmospheric pressure. As the dry air and the aqueous vapour mixed with it, press in common on the barometer, so that the up-borne column of mercury consists of two parts, one borne by the dry air, the other by the aqueous vapour, we may well understand that as with increasing temperature the air expands and by reason of its augmented volume rises higher and its upper portion overflows laterally,” etc.And in another place he says:“From the magnitude of the variations in the northern hemisphere and the extent of the region over which it prevails, we must infer that at the time of diminished pressure a lateral overflow probably takes place,” etc.Doubtless, the mean pressure of the atmosphere, in summer, in the northern hemisphere, is less than in winter, in some localities and greater in others and it differs in different countries of equal temperature. And this is all very intelligible. The mean of the pressure for the month is made up by averaging all the elevations and depressions. During a month, showing a very low mean, the barometer may, at times, attain its highest altitude, if the depressions below the mean are great or more frequent. The barometer is depressed during storms and ranges high during set fair weather. Ordinarily, therefore, the more stormy the season the more diminished the mean pressure; and it is a mistake to look to an overflow to account for the fact. The changes in the location of the atmospheric machinery and consequent change in the amount and severity of falling weather and the periodic frequency and character of storms and consequent periodic depressions and elevations of the barometer, explain the annual mean variations, as they do the other phenomena. But it is perfectly consistent with the calorific theory to attempt to account for these differences by another of those ever-necessary modifications, viz.: the different tension and elasticity of aqueous vapour in different countries of equal temperature; and then to suppose an expansion of the whole body of the atmosphere and a lateral overflow from the place where the air is expanded, on to some other, where it is not; and thus suppose all necessary currents in the upper regions, setting hither and yon, by the force of gravity alone. And apparently he who is best at supposition becomes the most distinguished meteorologist. Perhaps I have already said all that I ought to be pardoned for saying, in relation to the utter absurdity of attributing all meteorological phenomena to the agency of heat; but when I find such views as those which that article contains, emanating from so distinguished a man, sanctioned by the President of the British Association and copied into the leading journal of science in this country, I cannot forbear a further and a somewhat critical examination of them. There is more error of supposition and less truth in it, than in any other article regarding the science, of equal length, which has fallen under my notice.What is the height of this expansion?The moisture of evaporation ascends, ordinarily but a few thousand feet. The atmosphere grows regularly cooler, from the earth to the trade and the increased warmth that is felt at the surface extends but little way. Currents of warm air do not ascend. The strata maintain, substantially, their relative positions; and this is a most beneficent provision. In northern latitudes of the temperate zone, all the warmth derived from a few hours’ sunshine is needed at the surface; and, deplorable, indeed, would be our condition, if the atmosphere, as fast as warmed by the rays of the sun, were to hasten up and the frigid strata descend in its place. The earth would not be habitable. All the warm air on its surface would be rising as soon as it became warmed and the cold air above be descending and enveloping us with the chilling strata which are ever floating within two or three miles above us. No. Infinite wisdom has ordered it otherwise. The laws of magnetism and of static-electric induction and attraction keep the strata in their places and preserve to us the warmth which the solar rays afford or produce. The inhabitant of the valley, in a high northern latitude, in summer, can plant and sow and reap, at the base of the mountain whose summit penetrates the stratum of continual congealing and up its sides, almost to the line of perpetual snow; and, as he looks upon the fruits of his labour and up to the snow-clad peak that towers above him, can thank his Maker for placing a warm equatorial current, a perpetual barrier, between the fertility and warmth which surround him and the cold destructive strata above; and thank Him for not creating such a state of things, as certain meteorologists insist we shall believe He has created. Again, where are the upper regions, from which the lateral overflow takes place?The atmosphere is differently estimated, at from thirty to forty-five miles, or more, in height. Whatever its height may be, it is exceedingly attenuated in its “upper regions.”Gay-Lussac marked the barometer at 1295⁄100 inches at the height of 23,040 feet. Two thirds of the atmospheric density, then, is within five miles of the earth. Air, too, is compressible. Allowing for the latter and the attenuation, how many miles in vertical depth, of its “upper regions,” must move from one portion to another, to depress the barometer two inches; its range sometimes in twenty-four hours; or even half an inch?Let the computation be made and see how startling the proposition, how utterly impossible that the theory can be true.The distinguished Professor, in the paper referred to, introduces his theory of the formation of hurricanes and we quote; “If we suppose the upper portions of the air ascending over Asia and Africa to flow off laterally and if this takes place suddenly, it will check the course of the upper or counter-current above the trade-wind and force it to break into the lower current.“An east wind coming into a S. W. current must necessarily occasion a rotary movement, turning in the opposite direction to the hands of a watch. A rotary storm, moving from S. E. to N. W., in the lower current or trade, would, in this view, be the result of the encounter of two masses of air, impelled toward each other at many places in succession, the further cause of the rotation (originating primarily in this manner) being that described by me in detail in a memoir ‘On the Law of Storms,’ translated in the ‘Scientific Memoirs,’ vol. iii. art. 7. Thus, it happens that the West India hurricanes and the Chinese typhoons occur near the lateral confines on either side of the great region of atmospheric expansion, the typhoons being probably occasioned by the direct pressure of the air from the region of the trade-winds over the Pacific, into the more expanded air of the monsoon region and being distinct from the storms appropriately called by the Portuguese ‘temporales,’ which accompany the out-burst of the monsoon when the direction of the wind is reversed.”The analogy between this and a theory of Mr. Redfield’s, will be noticed further on. But I remark, in passing, that there is not a fact or inference in this paragraph which will bear examination.1. There is no such regular S. W. wind over the surface trade, as he supposes. Doubtless, there are, occasionally, secondary S. W. currents between the counter-trade and the surface one, with partial condensation, for much of both becomes depolarized by their reciprocal action and precipitation and these induced S. W. currents are sometimes so strong as to usurp the place of the surface-trade and become very violent in the latter part of hurricanes; but such is not the usual course of the upper currents of the West Indies, as the progress of storms there and observation, prove.2. There cannot be any periods of extensive and sudden expansion over Africa. If there is any place on the earth which has a more uniformly progressive temperature, either way and is more free from sudden extremes, or which is more arid and destitute of aqueous vapour and sudden aqueous expansions, than another, it is Africa. No such occasional sudden expansions are there possible.3. Winds do not and can not, “encounter.” They stratify upon each other. They are produced by the action of opposite electricity and are connected together in their origin and action. The atmosphere is never free from the regular and irregular currents, however invisible for the want of condensation. Aeronauts find them in the most serene days. They exist without encounter or tendency to rotation, everywhere and at all times; even over the head of the distinguished Professor, whether he sleeps or is awake. We can all see them when there is condensation and it is rarely the case that there is not some degree of it in some of them.4. That “Great region of expansion” is a chimera. It does not exist. It is a region of lower temperature and of condensation, instead of expansion of aqueous vapour. The trade does not rise in it, or the S. W. wind overflow from it. See the table cited page 165.5. The hurricanes do not originate in the surface trades, as he supposes. They originate in the belt of rains, the supposed “region of expansion,” and issue out of it; or in the counter-trade, where volcanic elevations rise far into or above the surface trade.6. This hypothesis cannot be sustained upon his own principles. The distance between Africa and the West India Islands, where most of the hurricanes originate, is from 2,500 to 3,000 miles. These gales are small when they commence, not ordinarily over one or two hundred miles in diameter and often less. There are trades all the way over from Africa and S. W. winds also, if they exist, as he supposes, in the West Indies. How can it happen that this lateral overflow should pass without effect, over 2,500 miles of S. W. wind and trade and concentrating the overflow of a continent over one small and chosen spot of the West Indies, pitch down there and there only and crowd the S. W. wind into the trade below?This is too much for sensible men to believe.What does Professor Dove mean by the term impulsion, as applied to the winds?How are they impelled?It is the fundamental idea of his calorific theory, that they are drawn by the suction caused by a vacuum and the vacuum created by expansion and overflow above, in obedience to the law of gravity; that the S. E. trade is drawn to the great region of expansion and the S. W. runs from it as an overflow. But if the S. W. is driven down into the plane and place of the surface-trades, how does it continue to be impelled and why is it not then subject to the suction of the vacuum which draws the trade?Does that vacuum select its air and so attract the trade, in preference to the depressed portion of the S. W. current, that the former runs around the latter to get to the vacuum and the latter around the former to get away from it?And does the trade, when it has got around the S. W. current, instead of going to the vacuum, continue to gyrate and the S. W. current, instead of pursuing its regular course, gyrate also about the trade and both move off together, regardless of the vacuum of the great region of expansion, in a new direction to the N. W., in an independent, self-sustaining, cyclonic movement, increasing in power and extent, involving extended and increasing condensation, producing the most violent electrical phenomena and thus continuing up, even to the Arctic circle?Yes, says Professor Dove. No, say all fact, all analogy and his own principles.7. His theory relative to the typhoons is unintelligible. If they originate near the lateral confines of the great region of atmospheric expansion, they originate in the region of the trade-winds, for the two are identical. How the direct pressure of the air from the trade-wind over the Pacific, in the more expanded air of the monsoon region, can occasion a typhoon upon any principles, passes my comprehension. If, as Lieutenant Maury supposes, the monsoons are reversed trades, then the trade-wind and monsoon region are identical. If the monsoons are found in the belt of rains, then, the trades, upon Professor Dove’s principles, pass into the monsoon region by attraction or suction, without pressure. Either way the theory is undeserving of consideration.A new theory has recently been started by Mr. Thomas Dobson, and, although it is (like all other efforts to get the upper strata down to produce condensation, or those below up, that they may be condensed), without foundation, his collection of facts is brief and interesting. I copy his article from the London, Edinburgh and Dublin Phil. Mag., for December, 1853. It adds to the collection of facts in relation to the connection between volcanic action and storms for the seventeenth century, made by Dr. Webster:The following appear to be the main facts which are available as a basis for a theory which shall comprehend all the meteors in question:1st. The eruption of a submarine volcano has produced water-spouts.“During these bursts the most vivid flashes of lightning continually issued from the densest part of the volcano and the volumes of smoke rolled off in large masses of fleecy clouds, gradually expanding themselves before the wind in a direction nearly horizontal and drawing up a quantity of water-spouts.”; (Captain Tilland’s description of the upheaval of Sabrina Island in June, 1811, Phil. Trans.)With this significant fact may be compared the following analogous ones:“In the Aleutian Archipelago a new island was formed in 1795. It was first observed after a storm, at a point in the sea from which a column of smoke had been seen to rise.” (Lyell, Principles of Geology.)“Among the Aleutian Islands a new volcanic island appeared in the midst of a storm, attended with flames and smoke. After the sea was calm, a boat was sent from Unalaska with twenty Russian hunters, who landed on this island on June 1st, 1814.”; (Journal of Science, vol. vii.)“On July 24th, 1848, a submarine eruption broke out between the mainland of Orkney and the island of Strousa. Amid thunder and lightning, a very dense jet black cloud was seen to rise from the sea, at a distance of five or six miles, which travelled toward the north-east. On passing over Strousa, the wind from a slight air became a hurricane and a thick, well-defined belt of large hailstones was left on the island. The barometer fell two inches.”; (Transactions Royal Society, Edinburg, vol. ix.)2d. Hurricanes, whirlwinds and hailstones accompany the paroxysms of volcanoes.“1730. A great volcanic eruption at Lancerote Island and a storm, which was equally new and terrifying to the inhabitants, as they had never known one in the country before.”; (Lyell, Principles of Geology, vol. ii.)“1754. In the Philippine Islands a terrible volcanic eruption destroyed the town of Taal and several villages. Darkness, hurricanes, thunder, lightning and earthquakes, alternated in frightful succession.”; (Edinburgh Philosophical Journal.)“In 1805, 1811, 1813 and 1830, during eruptions of Etna, caravans in the deserts of Africa perished by violent whirlwinds. In 1807, while Vesuvius was in eruption, a whirlwind destroyed a caravan.”; (Rev. W. B. Clarke in Tasw. Journal.)“1815, Java. A tremendous eruption of Tombow Mountain. Between nine and ten P.M., ashes began to fall and soon after a violent whirlwind took up into the air the largest trees, men, horses, cattle, etc.”; (Raffles’ History of Java.)“1817, Dec. Vesuvius in eruption. In the evening a hail storm, accompanied with red sand.”; (Journal of Science, vol. v.)“1820, Banda. A frightful volcanic eruption and in the evening an earthquake and a violent hurricane.”; (Annales de Chimie.)“1822, Oct. Eruption of Vesuvius. Toward its close the volcanic thunder-storm produced an exceedingly violent and abundant fall of rain.”; (Humboldt, Aspects of Nature.)“1843, Jan. Etna in eruption. Violent hurricanes at Genoa, in the Bay of Biscay and in Great Britain.“1843, Feb. Destructive earthquakes in the West Indies, a volcanic eruption at Guadaloupe, followed by hurricanes in the Atlantic.”“1846, June 26. Volcano of White Island, New Zealand, in eruption. Heavy squalls of wind and hail; it blew as hard as in a typhoon.”; (Commodore Hayes, R.N., in Naut. Mag., 1847.)“1847, March 20. Volcanic eruption and earthquake in Java; and on the 21st of March and 3d of April, violent hurricanes.”; (Java Courant.)“1851, Aug. 5. A frightful eruption of the long dormant volcano of the Pelée Mountain, Martinique. Aug. 17. Hurricane at St. Thomas, etc.; earthquake at Jamaica, etc.“1852, April 14. Earthquake at Hawaii and on the 15th a great volcanic eruption. On the 18th a gale of unusual violence lasted thirty-six hours and did great damage.”; (The Polynesian, April 22, 1852.)3d. In volcanic regions, earthquakes and hurricanes often occur almost simultaneously but in no certain order and without any volcanic eruption being observed.In 1712, 1722, 1815 and 1851, earthquakes and hurricanes occurred together at Jamaica; in 1762 at Carthagena; in 1780 at Barbados; in 1811 at Charleston; in 1847 at Tobago; in 1837 and 1848 at Antigua; in 1819, an awful storm at Montreal, rain of a dark inky colour and a slight earthquake. People conjectured that a volcano had broken out. In 1766 the great Martinique hurricane, a waterspout burst on Mount Pelée and overwhelmed the place. Same night, an earthquake.1843, Oct. 30. Manilla.; Twenty four hours’ rain and two heavy earthquakes. 10 P.M., a severe hurricane.“1852, Sept. 16. Manilla; An earthquake destroyed a great part of the city; many vessels wrecked by a great hurricane in the adjacent seas, between the 18th and 26th of September.”; (Singapore Times.)“1731, Oct. Calcutta.; Furious hurricane and violent earthquake; 300,000 lives lost.”“1618, May 26. Bombay.; Hurricane and earthquakes; 2,000 lives lost.”; (Madras Lit. Tran., 1837.)“1800. Ongole, India and in 1815, at Ceylon, a hurricane and earthquake shocks.”; (Piddington.)“1348. Cyprus.; An earthquake and a frightful hurricane.”; (Hecker.)“1819. Bagdad.; An earthquake and a storm; an event quite unprecedented.“1820, Dec. Zante.; Great earthquake and hurricane, with manifestations of a submarine eruption.”; (Edinburg Phil. Journal.)“1831, Dec. Navigator’s Islands.; Hurricane and earthquakes.”; (Williams’ Missionary Enterprise.)“1848, Oct., Nov. New Zealand.; Succession of earthquake shocks and several tempests.“1836, Oct. At Valparaiso, a destructive tempest and severe earthquakes.”; (Nautical Magazine, 1848.)When an earthquake of excessive intensity occurs, as at Lisbon, in 1755, the volcanic craters, which act as the safety-valves of the regions in which they are placed, are supposed to be sealed up; and it is a remarkable and highly-suggestive fact, that no hurricane follows such an earthquake. The number of instances of the concurrence of ordinary earthquakes and hurricanes might easily be increased but the preceding suffices to show the generality of their coincidence, both as to time and place.4th. The breaking of water-spouts on mountains sometimes accompanies hurricanes.In 1766, during the great Martinique hurricane, before cited.“1826, Nov. At Teneriffe, enormous and most destructive water-spouts fell on the culminating tops of the mountains and a furious cyclone raged around the island. The same occurred in 1812 and in 1837.” (Espy and Grey’s Western Australia.)“1829. Moray.; Floods and earthquakes, preceded by water-spouts and a tremendous storm.”; (Sir T. D. Lander.)“1826, June. Hurricanes, accompanied by water-spouts and fall of avalanches, in the White Mountains.”; (Silliman’s American Journal, vol. xv.)5th. The fall of an avalanche sometimes produces a hurricane.“1819, Dec. A part (360,000,000 cubic feet) of the glacier fell from the Weisshorn (9,000 feet). At the instant, when the snow and ice struck the inferior mass of the glacier, the pastor of the village of Randa, the sacristan and some other persons, observed a light. A frightful hurricane immediately succeeded.”; (Edinburg Philosophical Journal, 1820.)6th. Water-spouts occur frequently near active volcanoes.This is well known with regard to the West Indies and the Mediterranean. The following notices refer to the Malay Archipelago and the Sandwich Islands:“Water-spouts are often seen in the seas and straits adjacent to Singapore. In Oct., 1841, I saw six in action, attached to one cloud. In August, 1838, one passed over the harbor and town of Singapore, dismasting one ship, sinking another and carrying off the corner of the roof of a house, in its passage landward.”; (Journal of Indian Archipelago.)“1809. An immense water-spout broke over the harbor of Honolulu. A few years before, one broke on the north side of the island (Oahu), washed away a number of houses and drowned several inhabitants.”; (Jarves’ History of Sandwich Islands.)7th. Cyclones begin in the immediate neighbourhood of active volcanoes.The Mauritius cyclones begin near Java; the West Indian, near the volcanic series of the Caribbean Islands; those of the Bay of Bengal, near the volcanic islands, on its eastern shores; the typhoons of the China Sea, near the Philippine Islands, etc.8th. Within the tropics, cyclones move toward the west; and, in middle latitudes, cyclones and water-spouts move toward the N. E., in the northern hemisphere and toward the S. E. in the southern hemisphere.9th. In the northern hemisphere, cyclones rotate in a horizontal plane, in the order N. W., S. E.; and in the southern hemisphere, in the order N. E., S. W.By applying the principles of electro-dynamics to the electricity of the atmosphere, I shall endeavour to connect and explain the preceding well-defined facts. The continuous observations of Quetelet, on the electricity of the atmosphere, from 1844 to 1849 (Literary Journal, February, 1850), show that it is always positive and increases as the temperature diminishes. It therefore increases rapidly with the height above the earth’s surface. We may, consequently, regard the upper and colder regions of the atmosphere as an immense reservoir of electric fluid enveloping the earth, which is insulated by the intermediate spherical shell formed by the lower and denser atmosphere. Now, whenever a vertical column of this atmosphere is suddenly displaced, the surrounding aqueous vapour will be immediately condensed and aggregated and the cold rarefied air and moisture will form a vertical conductor for the descent of the electrical fluid. This descent will take place down a spiral, gyrating in the order N. W., S. E., in the northern hemisphere, since the electric current is under the same influence as that of the south pole of a magnet; and in the order N. E., S. W., in the southern hemisphere. The air exterior to the conducting cylinder will partake of the violent revolving motion and a tornado or cyclone will be produced.Upon the foregoing facts I shall comment in another place.
I edited the next two chapters on my lap-top and it broke down again.I need to get rich quick. Any ideas?I took the cable into the shop I bought it from and they seemd to be at a total loss what to do. A cable on E-bay is about 7 or 8 quid but I don't have an online account of any sort.It is really good here.And I have a day's charts on the blinking thing too!AAAAARRRRRRRRGH!!!!!!!
Originally posted by tdjmd1:
So what did you think of the stuff so far. Fun, eh?