214 Process to avert Showers of Hail, 
_ M. Denize, after having examined the history of antiquity 
to ascertain if the antients knew any thing on the subject, 
concludes, if they did, that they have left us nothing instruc- 
tive on the subject. Among the moderns he finds no other 
practice resorted to than that of ringing the church bells ; 
and he observes, with great reason, that this method of avert- 
ing a storm may be regarded as purely superstitious, and as 
affording no physical preventive whatever. 
The author then proceeds to an examination of the pro- 
cess resorted to of exploding gunpowder ; a process, as he 
says, only adopted within these few years, and the aduption 
of which he ascribes to two causes: ‘* On the one hand, the 
suppression of the ringing of bells since the revolution; on 
the other hand, some observations which lead us to think 
that the commotions excited in the air by considerable dis- 
charges of artillery are sufficient to prevent hail; storms 
being far less frequent, or at least very moderate, in the 
track of camps or armies*.” 
The investigations J procured to be made taught me, that 
so far from the suppression of bell-ringing having had any 
influence in encouraging the gunpowder process, the latter 
has been in use for upwards of five-and-thirty vears in one 
of the communes of the ci-devant Maconnais, as I shall — 
afterwards demonstrate. I shall add to the observations 
which appear to M. Denize to be the second cause of the 
adoption of the above method, a fact which convinced me of 
the influence exercised upon dense clouds by strong and reite- 
rated explosions. JT was led personally to make this remark 
at Grenoble, where there is a school of artillery established. 
The sky was pure and serene, when about nine 6’clock 
in the morning numerous clouds began to extend over all 
the valley in which Grenoble is situated, and covered the 
mountains by which it is bounded. The instant the dis- 
charges of the field-pieces commenced, between nine and 
ten o’clock, the clouds opened away before us, and the sky 
resumed its serenity. They did not again collect until the 
exercise of the guus was finished. 
* For some,curious remarks on this subject see Philosophical Magazine, 
vol, iv. p. $33. 
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