218 ANNUAL OF SCIENTIFIC DISCOVERY. 



great heats of those regions, and to prevent the Polar regions from becom- 

 ing blocked up with accumulating mountains of ice, which, but for this 

 provision, would soon be pushed down as extensive glaciers, rendering 

 whole tracts of our temperate zones uninhabitable wilds. 



PROTECTION AGAINST HAIL. 



The second volume of the works of Arago have called attention to 

 several points in Meteorology. In the chapter which he devotes to the 

 subject of hail, he states, that, in 1847, two small agricultural districts 

 of Boxirgogne had lost by hail crops to the value of a million and a 

 half of francs. Certain of the proprietors from the neighborhood went 

 to consult Arago on the means of protecting them from like disasters. 

 Resting on the hypothesis of the electric origin of the hail, he suggested 

 the discharge of the electricity of the clouds by balloons communicating 

 by a metallic wire with the soil. These projects, however, were not car- 

 ried out ; and in view of the doubts as to the electric origin of hail, he 

 proposed to investigate the subject anew. He had not the time to bring 

 out any results ; but he persisted in believing in the effectiveness of the 

 method proposed. Another subject is discussed in this volume. Arago 

 inquires whether the firing of cannon can dissipate storms. He cites 

 iseveral cases in its favor, and others which seem to oppose it ; but he 

 concludes by recommending it to his successors. Whilst Arago was pro- 

 pounding these questions, a man not conversant in science, the poetMery, 

 was collecting facts supporting the view, and has since published his 

 results. In a remarkable pamphlet entitled " Paris Futur," he con- 

 cludes strongly on the efficaciousness of the firing of cannon in dissipating 

 storms, and mentions numerous observations in support of it. He says 

 that his attention was called to the subject in 1828, while an assistant at 

 the " Ecole de tir " of Yinceimes. Having observed that there was never 

 any rain on the morning of the exercise of firing, he was led to examine 

 the annals of military and revolutionary science, and he found there, as 

 he says, facts which justified the expressions which became common, such 

 as " Le soleil d'Austerliz," " Le soleil de Juillet," upon the morning of 

 the revolution of July, and he concluded by proposing to construct around 

 Paris 12 towers of great height, which he calls " tours imbrifuges," 

 (imbrifugal towers,) each carrying 100 cannons, which should be dis- 

 charged into the air on the approach of a storm. 



About this time an incident occurred, which in no ways confirmed the 

 truth of M. Mery's theory. The 14th of August was a fine day. On the 

 loth, the J tie of the Empire, the sun shone out, the cannon thundered all 

 day long, fire- works and illuminations were blazing from 9 o'clock in the 

 evening. Everything conspired to verify the hypothesis of M. Mery, and 

 chase away storms for a long time. But towards 11 in the evening a tor- 

 rent 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. Paris Cor. of SilUmans Journal. 



