1806. ] 
Before he enters into the detail of the 
new expedients which he fubmits to the 
judgment of {cientific men, M. Denize 
thinks fit to exhibit the refults of his own 
oblervations on the formation of hail. It 
will not be uninterefting to follow him ia 
this development. 
The principles on which the author 
grounds his opinion may be thus ftated. 
The elements which enter into the com- 
pofition of ftorms are atmofpheric air, 
water, electricity, and caloric. 
Water dilated by caloric refolves into 
vapours, and having become {pecifically 
light er than atmofpheri ic air, it rifes and 
carries with ita mais of electricity propor- 
tioned to the capacity it has acquired. 
It the air in which thefe vapours are 
fulpended is of a temperature inferior to 
theirs, they will be condenfsd by the dif- 
engagement of their caloric into clouds 
more or lefs thick. 
Their dimenfions being diminifhed un- 
der this new form, they will contain a fu- 
perabundant quantity of eleétricity, which 
they may difcharge by communicaticn 
either with others, or with the earth, by 
means of conduétors ; but they will foon 
recover their electricity, "1 Pa traverfing 
céyiain regions of the air abounding in ca- 
loric, they are reftored to their firit fate 
of dilatation. 
Storms. proceed from the contact of 
clouds at various degrees of electricity, the 
electric fluid fuccefively darting Rane one 
to another to obtain an equilibriom. 
As the author explains the formation of 
Crops of rain during ftorms, and confe- 
quently that of hail, ina manner which 
appears to me peculiar to himfelt, that is, 
by the commotion produced in the atmo- 
{phere of the clouds by the lightning, I 
fall Guote what he jays on tha: fubjcét ; 
** As foon as the lightning begitts to 
burft from the bofom ot the ftorm, “che ex- 
plofion which it produces fhakes all the 
parts of the furrounding air, at the fame 
time that it fuddenly diminithes its den- 
fity. This fhock occations violent vibra- 
tions in the fmailef particles of the air, of 
courfe detaches from it the heavieft humid 
particles, and forces them to a mutual ap- 
proximation, They unite by virtue of 
their attraGtion, and immediately fall in 
drops of rain, the fize of which is propor- 
tioned to the quantity of particles of wa. 
ter that have been united to them during 
their fall. 
“Tt is commonly at this moment that 
the formation of hail is effeCted whenever 
it is to take place.” 
The author’s theory for explaining the 
I 
to prevent Fail and diffipate Storms, 
525 
phenomena which take place fucceffively 
till the conclufion of the ftorm, is exactly 
the (ame as that given of the fame pheno- 
mena by M. Guyton de Morveau in the 
above-mentioned Memoir. 
The following, accerding to M. Denize, 
are the characters by which we are to 
judge that it is time to put in practice the 
pre‘ervative expedients. 
“¢ As fuon (fays he,) as thick and dark 
clouds begin to accumulate, if you per- 
ceive that violent and impetuous winds 
tend to comprefs thém one againft an- 
other, and to condenfe them ftrongly, as 
foon as you hear the thunder begin to roll 
in the midit of them, and they appear ifo- 
lated in the air, communicating with the 
earth only by means of thick fogs or abun- 
dant thowers, *tis then that the danger 
prefles, and you cannot be teo expeditious 
to interpofe between thefe clouds and the 
furface of the earth the mof powerful and 
energetic conductors.” 
elt appears to me that the expedients 
approved by the author for difperfing 
ftorms may be claffed in three divifions, 
and that, though he has followed no order 
in the indication of thefe means, they may 
be reduced to the three following Rrope 
tions. 
1. To excite in the air violent commo- 
tions capable of fhaking the particles of 
water which adhere to it, and thus pro- 
duce an abundant rain.. 
This objc&t may be obtained by the 
found of great bells, the repeated firing of 
cannon, the beating of droms, the detona« 
tion of fulminating pewder, and the ex- 
piofion, in the midft of the clouds, of 
rockets thrown up towards the darkeft 
places. 
2. Fo interpofe energetic conduéters 
between the clouds and* the earth, either 
by fires kindled at diftances ‘and kept up 
with dry matters, or by the difengage- 
ment of humid vapours, or by the com- 
buflion of refincus fubftances. 
3. Lo draw off the electric fluid con- 
tained in fuperabundance in the clouds, 
by means of numerous eleétric conductors, 
As thunder-forms come in this country 
(France,) with a weit and fouth-weit 
wind, it would be of importance to fix up 
thefe conductors in each canton in that 
quarter of their horizon. They fhou'd 
be paced either on very lofty fituations, 
or on the tops. of the higheft trees. 
This confideration would tend to multiply 
lofty trees in thole parts; and hence 
would accrue immenife advantages with 
regard to the augmentation of fuel, 
Such is the fuccinét analyiis of this Me- 
Moir, 
