152 ELECTRICAL I]SrFLTJEN"CE OF TREES. 



plague.* The paragrandini,\ whicli the learned curate of E.i- 

 volta advised to erect, with sheaves of straw set up vertically, 

 over a great extent of cultivated country, are but a Liliputian 

 image of the vast paragranduii, pines, larches and firs, which 

 nature had planted by millions on the crests and ridges of the 

 Alps and the Apennines." :j: " Electrical action being diminished," 

 says Meguscher, " and the rapid congelation of vapors by the ab- 

 straction of heat being impeded by the influence of the woods, it 

 is rare that hail or waterspouts are produced within the precincts 

 of a large forest when it is assailed by the tempest." § Arthur 

 Young was told that since the forests which covered the moun- 

 tains between the Riviera and the county of Montferrat had dis- 

 appeared, hail had become more destructive in the district of Ac- 

 qui,II and a similar increase in the frequency and violence of hail- 



* There are, in Northern Italy and in Switzerland, joint-stock companies 

 which insure against damage by hail, as well as by fire and lightning. Between 

 the years 1854 and 1861, a single one of these companies. La Riunione Adri- 

 atica, paid, for damage by hail in Piedmont, Venetian Lombardy and the 

 Duchy of Parma, above 6,500,000 francs, or nearly $200,000 per year. The 

 total damage by hail in the Northern Provinces of Italy, between 1834 and 

 1880, is estimated at 358,000,000 francs, and the Assicurazione Generale of Ven- 

 ice states, in its public notices issued at the beginning of 1883, that it had 

 paid out for damages by hail, during the preceding three years, the sum of 

 8,193,906 francs, equal to $1,638,780. 



f The paragrandim, or, as it is called in French, the paragrele, is a species 

 of conductor by which it has been hoped to protect the harvests in countries 

 particularly exposed to damage by hail. It was at first proposed to employ for 

 this purpose poles supporting sheaves of straw connected with the ground by 

 ropes of the same material ; but the experiment was afterwards tried in Lom- 

 bardy on a large scale, with more perfect electrical conductors, consisting of 

 poles secured to the top of tall trees and provided with a pointed wire enter- 

 ing the ground and reaching above the top of the pole. It was at first thought 

 that this apparatus, erected at numerous points over an extent of several 

 miles, was of some service as a protection against hail, but this opinion was 

 soon disputed, and does not appear to be supported by well-ascertained facts. 

 The question of a repetition of the experiment over a wide area has been 

 again agitated within a very few years in Lombardy ; but the doubts ex- 

 pressed by very able physicists as to its efficacy and as to the point whether 

 hail is an electrical phenomenon, have discouraged its advocates from attempt 

 ing it. 



X Cenni sulla Importanza e Coltura dei BoscM, p. 6. 



§ Memoria sui BoscM, etc. , p. 44. 



II Travels in Italy, chap. iii. 



