Arago relates, that when, in 1847, two small agricultural districts
of Bourgoyne had lost by Hail crops to the value of a million and a
half of francs, certain of the proprietors went to consult him on the
means of protecting them from like disasters. Resting on the hypothesis
of the electric origin of hail, Arago suggested the discharge of
the electricity of the clouds by means of balloons communicating by
a metallic wire with the soil. This project was not carried out;
but Arago persisted in believing in the effectiveness of the method
proposed.
Arago, in his _Meteorological Essays_, inquires whether the firing
of cannon can dissipate storms. He cites several cases in its
favour, and others which seem to oppose it; but he concludes by
recommending it to his successors. Whilst Arago was propounding
these questions, a person not conversant with science, the poet
Méry, was collecting facts supporting the view, which he has
published in his _Paris Futur_. His attention was attracted to the
firing of cannon to dissipate storms in 1828, whilst an assistant
in the “Ecole de Tir” at Vincennes. Having observed that there was
never any rain in the morning of the exercise of firing, he waited
to examine military records, and found there, as he says, facts
which justified the expressions of “Le soleil d’Austerlitz,” “Le
soleil de juillet,” upon the morning of the Revolution of July;
and he concluded by proposing to construct around Paris twelve
towers of great height, which he calls “tours imbrifuges,” each
carrying 100 cannons, which should be discharged into the air on
the approach of a storm. About this time an incident occurred which
in nowise confirmed the truth of M. Méry’s theory. The 14th of
August was a fine day. On the 15th, the fête of the Empire, the
sun shone out, the cannon thundered all day long, fireworks and
illuminations were blazing from nine o’clock in the evening. Every
thing conspired to verify the hypothesis of M. Méry, and chase
away storms for a long time. But towards eleven in the evening
a torrent of rain burst upon Paris, in spite of the pretended
influence of the discharge of cannon, and gave an occasion for the
mobile Gallic mind to turn its attention in other directions.