^280 Proximate Causes of certain Winds and Storms. 



very fully explained. This position is established and illustrated by 

 the five following: arguments. 



6 "'& 



1. The progress of the wind during a thunderstorm is commonly 

 much more rapid than that of the storm itself. The cloud and rain 

 move at the rate of not more than eight or ten miles an hour, whilst 

 the wind is blowing at the rate of thirty, prostrating often forests, as 

 well as the structures erected by man, as it advances. It is per- 

 fectly calm before the storm, and if there be any wind, it is but a 

 gentle breaze on each side of it and behind it. Where does this 

 rapid current come from, if not from above, and whither does it go, 

 if it is not again whirled aloft. The cool lateral breeze, that i 

 sometimes felt in the neighborhood of a cloud, may be, and proba- 

 bly is, the effect of the lateral communication of motion from the 

 falling drops to the air through which they pass, resembling there- 

 fore in its origin the current of air by which the blast is maintained 

 m the forges of North Carolina ; but the violent wind, blowing in the 



direction in which the cloud moves, cannot be accounted for in this 

 way. 



2. Aeronauts select a calm clear day for their voyage, and do not 

 launch their car into the bosom of a thundercloud. From the hisio- 

 ries of the persons engaged in this kind of navigation, to which I 

 have access, and which are not very numerous, I have been able to 

 collect only the following facts having a bearing upon the question 

 before us. A Mr. Crosbie, who ascended from Dublin, in July, 

 1785, entered a thick cloud, and strong blasts of wind, with thunder 

 and lightning, which brought him rapidly towards the surface of the 

 water. M. Blanchard, ascending from Strasburg, on the 26th of 

 August, 1787, in " horrible " weather, let off a parachute with a dog 

 attached to it, at an elevation of a little more than a mile, which, in- 

 stead of descending, was carried by a whirlwind above the clouds. 

 Blanchard afterwards fell in with the dog again in the course of his 

 voyage. He was bending his course directly downwards, but pres- 

 ently lifted by another whirlwind to a great height. 



. The ascending and descending currents, to which the phenomena 

 of storms are attributed in this paper, do not therefore rest on mere 

 hypothesis, but have as much direct and positive evidence of their 

 existence, as the case seems to admit. The curvature of the circle 

 or ellipsis, in which the wind is supposed to revolve, is so small, thnt 

 Ks power of raising bodies from the earth must be extremely feeble, 

 yet it were an easy matter to collect from the Philosohical Transac- 



