PEODUCED BY MAN. 805 



accordance with his own theory, look upon a fir-tree when shrouded 

 as M. Fautrat has described it, with a differentially thick envelope 

 of vapour, as having thus clothed itself by virtue of the attractive 

 effect of its myriad points. For electricity tending constantly to 

 an equal distribution, so fast as the surcharge of electricity on the 

 particles of vapour nearest the trees was carried away, so fast would 

 the balance be redressed by supply from the particles more distantly 

 placed. And thus in accordance with this theory, particles of 

 watery vapour would be constantly setting in the direction of the 

 conducting and attracting leaves and twigs. Becquerel's view, 

 already quoted, according to which the plague of hail which has so 

 often ^ been observed to follow upon the destruction of the woods 

 of a country, is to be ascribed to the loss of the lightning-conductors 

 which the cut-down trees represented, while standing, and to the 

 absence consequently of the incessant though insensible dissipating 

 agency of the trees, appears to me to show that he would doubtless 

 have allowed that Mr. Rowell's theory contains some, at least, of 

 the elements of the true and complete theory of rain. It is not for 

 me to meddle with memoirs in which neither living animal nor 

 living vegetable organisms are concerned^ otherwise I might have 

 referred to Lord Rayleigh's paper in ' The Proceedings of the Royal 

 Society,' March 13th, 1879, pp. 406, 409. But as regards the views 

 they brought forward, and to a considerable extent as regards the 

 whole question, I scarcely feel myself to be in a position to give any 

 decided opinion. 



That trees, like other beneficent agencies, do not fail to benefit 

 themselves whilst thus benefiting the world at large, may be well 

 gathered from the following passage from Professor Grandeau's 

 work now in course of publication, ' Chimie et Physiologic ap- 

 pliquees k FAgriculture et a la Sylviculture, 1879, Pt. I, la nutrition 



1 See a really pathetic account of this given as having been produced during his 

 seven years' absence from Thuringen by Fischer at p. 164 of his charming 'Beitrage 

 zur physischen Geographic der Mittehneerlander,' 1877. Rain and hail-storma had 

 become frequent, and the fishing brook had disappeared together with the wood of his 

 boyhood. He adds :— 



' Ich will gewiss damit nicht sagen, dass in jenen Gegend jetzt auch nur ein 

 TrofFchen Regen weniger falle als fruher, obwol auch das ortlich moglich, ja wahr- 

 scheinlich ist, aber der Vertheiler und Bewahrer der Feuchtigkeit fehlt und so konnen 

 locale Ursachen zeitweilig Wirkung haben, die in Sud-Europa allgemeinen kosmischen, 

 aber durch ortliche verstarkten zu zuschreiben est. Ich wurde recht lebhaft an 

 Sicilien erinnert, aus dcm ich eben heimkehrte.' 



