216 Process to avert Showers of Hail, - 
its density. This concussion occasions violent vibrations in 
the smaller molecules of the air; consequently i it detaches 
from them the heaviest humid particles, and forces them | 
mutually to approach each other. They unite in virtue of 
their attraction, and they are immediately precipitated in 
drops of rain, the size of which is proportioned to the quan- 
tity of particles of water which have been united to them 
during their fall. 
“¢ It is generally at this moment that the formation of 
hail takes place.” 
The theory of the author for explaining the phenomena 
that successively take place during a storm, is precisely the 
same with the theory ascribed to the same phenomena by 
M. Guyton de Morveau in his above-mentioned memoir. 
The following, according to M. Denize, are the characters 
according to which we may judge when it is time to put m 
practice the preservative processes : 
«’ From the moment that the thick and obscure clouds 
begin to accumulate, if we perceive that violent and impe- 
tuous winds tend to compress them the one against the 
other, and to condense them strongly, and as soon as we 
hear the thunder roaring in the middle of these clouds, and 
when they appear isolated in the air, and not communi- 
cating with the earth by means of any mists or undulations, 
it is ies that the danger threatens, and we cannot too spee- 
dily establish the most powerful and energetic conductors 
between these clouds and the surface of the earth.” 
I think we may class under three divisions the methods. 
recommended by the author for dispersing storms: and it 
seems to me that, although he has followed no order in the 
indication of these methods, they may be reduced to the fol- 
lowing three propositions : 
1. Excite in the air strong commotions capable of shaking, 
if we may use the expression, the particles of water adhering 
to it, so as to produce an abundant rain. 
We may attain this object by the sound of great bells, 
the reiterated noise of guns or drums, &c.; by the detona- 
tion of the fulminating powder, and by the explosion, in the 
middle 
bs eae 
