PRODUCED BY MAN. 801 



dried fountain. If the water thus thrown upon the surface, thus 

 modified, finds its way into a basin properly proportioned as to 

 cubical, as to square area, and as to water-holding power, we may 

 have a lake formed, as in the case related above by Mr. Abbay. It 

 is, of course, more usual to find one or other, or two, or all, of these 

 favourable conditions wanting, and in the more numerous class of 

 cases we find that the diminution of wood and the diminution of 

 water go hand in hand. I would go further than this, and aver 

 that the diminution of wood and the diminution of water in the 

 shape of ice may not only also go hand in hand, but may also be 

 connected as cause and effect. M. Viollet-le-Duc, in his delightful 

 work on ^ Mont Blanc,' 1877 (translated by B. Bucknall, pp. 341 

 353)i ^^^lls us that — 



'Although the glaciers have been tending to diminish for the last forty years in 

 a somewhat rapid ratio, which would seem to indicate an elevation of the mean 

 temperature, the forests are quitting the heights where they still lingered, to take a 

 lower position. Is there any connexion between these two results ? We shall not 

 endeavour to solve the problem.' 



It is a little presumptuous to address one's-self to it after this deter- 

 rent warning. Still M. Viollet-le-Duc has (1. c. pp. 339, 377) shown 

 us that the destruction of the forests is abundantly explained irre- 

 spectively of any inorganic agency by the mischievous action of 

 man working as a goatherd and a woodcutter. His descriptions of 

 these operations are couched in language of real pathos and eloquence, 

 but scientifically it shows us that we need not look for any other 

 cause for the disappearance or shrinking of the limits of the forests. 

 The spruces and the larches, for such are the trees, being thus 

 destroyed by the ' essentially destructive power ' of man, how can 

 their destruction be shown to entail the diminution of the glacier ? 

 I think the loss of these trees as evaporating agencies may be taken 

 as a vera ac sufficiens causa for the diminution. A great deal of 

 much interest has been written ^ upon the difierence in the amount 

 of watery vapour given off by various trees and by the cerealia, 

 which last, and amongst which last, as might be expected from 

 their deep roots and the amount of their Stoffwechsel, wheat-plants 

 stand quantitatively pre-eminent. But for our present purpose it 

 is sufficient to point out that the rays which strike on the mass of 

 a glacier are, to say nothing of the other conditions of disadvantage 

 which such a mass opposes to them, enormously outnumbered by the 



1 See Vogel, Pfaff, and Hartig, cit. Ebermayer, 1. c, p. 185. 

 3F 



