I'm sure I saw an article about Fujita inventing this. OK; so they had to wait a lot longer for the nvetion of the second wheel…. …
CORRESPONDENCE AND NOTES. Tornado Cloud Experiment
Experiment illustrating the Formation of the Tornado Cloud.— The following experiment is so easily performed, and imitates so exactly on a small scale the mechanism of a Tornado or Waterspout, that it seems worth describing.
Obtain an old box or packing case about 2 feet square and 18 inches high. In the centre of the top cut a round hole about 3 inches diameter, and in it fix a few feet of stove pipe. Remove one side of the box, or preferably, for the sake of light, two opposite sides, and replace by window glass, leaving, however, a narrow opening on one side only between the glass and the side, about I[?] inch to 1 inch broad and extending to the full height.
Place in the bottom of the box a circular vessel filled with hot water, and then by any available means obtain a strong draft up the stove pipe.
The characteristic funnel cloud is soon seen extending from the water to the mouth of the pipe at the top of the box, and if the draft be strong, and the conditions favourable, a decided protuberance is seen on the surface of the water just under the end of the cloud.
The draft can be obtained by burning a jet of gas in the stove pipe, and this is sufficient to form the cloud, but will hardly raise the protuberance on the water.
The success of the experiment seems to depend on a strong draft up the chimney, and on directing the air as it enters the box so that it has the greatest possible angular momentum about the centre, and also on perfectly quiet and steady conditions in the surrounding air, for the funnel when formed is easily broken up by any irregular draft.
There seems no doubt but that the cloud is formed by true dynamic cooling, as the air, saturated by the vapour from the hot water, comes under the influence of the decreased pressure at the centre; for I have not been able to form the cloud with smoke.
The circular motion and the rapid whirl are quite apparent, and can be proved by dropping any light objects into the box, also powder or soap suds floating on the water are instructive.
Probably the sizes given above are quite immaterial, but they are the first and only ones I have tried.
W. H. Dines, Oxshott, April 18th, 1895.
Wasn’t the substance of this experiment what Fujita reproduced to no small acclaim among his peers not that long ago?
I believe his appliance though similar consisted of floor vents similar to a rain grid or a solitaire board.