154 ELECTRICAL INFLUENCE OF TREES, 
’ 
desolates the fertile plains of Lombardy, was much less fre- 
quent; but since the general prostration of the forest, these 
tempests are laying waste even the mountain-soils whose older 
inhabitants scarcely knew this plague.* The paragrandini,+ 
which the learned curate of Rivolta advised to erect, with 
sheaves of straw set up vertically, over a great extent of culti- 
vated country, are but a Liliputian image of the vast para- 
grandini, pines, larches, and firs, which nature had planted by 
millions on the crests and ridges of the Alps and the Apen- 
nines.” ¢ “ Hiectrical action being diminished,” says Meguscher, 
“and the rapid congelation of vapors by the abstraction 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 mountains 
between the Riviera and the county of Montferrat had dis- 
appeared, hail had become more destructive in the district of 
Acqui,| and a similar increase in the frequency and violence 
* There are, in Northern Italy and in Switzerland, joint-stock companies 
which insure against damage by hail, as well as by fire and lightning. Be- 
tween the years 1854 and 1861, a single one of these companies, La Riunione 
Adriatica, paid, for damage by hail in Piedmont, Venetian Lombardy, and the 
Duchy of Parma, above 6,500,000 francs, or nearly $290,000 per year. 
+ The paragrandine, or, as it is called in French, the paragréle, 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 
the same material ; but the experiment was afterwards tried in Lombardy 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 entering the ground 
and reaching above the top of the pole. It was at first thought that this ap- 
paratus, erected at numerous points over an extent of several miles, was of 
some service as a protection against hail, but this opinion was svon 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 expressed by very able 
physicists as to its efficacy, and as to the point whether hail is an electrical 
phenomenon, have discouraged its advocates from attempting it. 
t Cenni sulla Importanza e Coltura dei Boschi, p. 6. 
§ Memoria sui Boschi, ete., p. 44. | Zvavels in Italy, chap. iii, 
