Much interested in WCR's paper on "Whirlwinds excited by fire" [Am. J. Sci. 36 (1839): 50–9; Edinburgh New Philos. J. 27 (1839): 369–79].
Sends a summary account of circular clouds and waterspouts formed during volcanic eruption in the Azores [S. Tillard, "Eruption of a volcano in sea off St Michael", Philos. Trans. R. Soc. Lond. (1812): 152–8].
12 Upper Gower St | London.
Having been much interested by your paper on “Whirlwinds excited by Fire”, which has been republished in the Edinburgh New Philosophical Journal, I venture to call your attention to a published account of the effect of a volcanic eruption, which may possibly have escaped your notice.—
When the Island of Sabrina was formed off the Azores, Capt. Tillard (Philosoph Transacts of the Royal Soc 1812 p. 152) describes an immense body of smoke rising from the sea, which, when “in a quiescent state had the appearance of a circular cloud revolving on the water like an horizontal wheel in various & irregular involutions &c &c”. He then adds “the cloud of smoke now ascending to an altitude much above the highest point, to which the ashes were projected, rolled off in large masses of fleecy clouds, gradually expanding themselves before the wind in a direction nearly horizontal, and drawing up to them a quantity of water-spouts, which formed a most beautiful & striking addition to the general appearance of the scene.”—
This fact appears to me singularly interesting in relation to what you have said in
Arti: 11 of your conclusions. Taking your account of the whirlwinds produced by
artificial fires, we here see the vera causa of one set of waterspouts.— This
case appears to me the more important, because the inference, deduced by Prof.
Œrsted from the accounts which he has compiled of water-spouts &
whirlwinds (a translation of whose paper appeared in the number (53) of the Edinburgh
New Phil. Journal, previous to that which contained yours)
seems to be that the cause lies in the currents of air flowing in opposite directions
but following a parallel course.— In the case of Sabrina Isl
I trust you will excuse the liberty I have taken in addressing you: having witnessed waterspouts on the coast of Brazil, I have al<ways> felt a great curiosity, to understand their origin, & therefore could not resist the temptation of being possibly instrumental in adding a single fact to the data, which you already possess, & which you have brought to bear in so admirable manner on meteorological phenomena.—
With the highest respect | I have the honour to remain | Sir | Your obedient servant | Chas: Darwin
- f1 556.f1Redfield 1839a. The article appeared originally in the American Journal of Science and Arts (Silliman's Journal).
- f2 556.f2Tillard 1812.
- f3 556.f3Oersted 1839.