Geology and Natural History. 411 
go 
cleus, the work expended in mutual crushing and dislocation of its 
: ; p 
ments completed by him:—the one on the actual amount of heat 
capable of being Es 
Species of rocks, chosen so as to be representative of the whole series 
of known rock formations from Oolites down to the hardest erys- 
talline rocks; the other, on the co-efficients of total contraction 
between fusion and solidification at existing mean temperature 
of the atmosphere of basic and acid slags, analogous to melted 
roc 
The latter experiments were conducted on a very large scale, 
and the author points out the great errors of preceding experi- 
menters, Bischoff and others, as to these co-efficients. 
By the aid of these experimental data, he is enabled to test the 
theory produced when compared with such facts as we possess as 
to the rate of present cooling of our globe, and the total annual 
ees of volcanic action taking place upon its surface and within 
crust. 
He shows, by estimates which allow an ample margin to the 
best data we possess as to the total annual vulcanicity of all sorts 
of our globe at present, that less than one fourth of the total heat 
at present annually lost by our globe is upon his theory sufficient 
_ to account for it; so that the secular cooling, small as it is, now 
S0lng on is a sufficient primum mobile, leaving the greater portion 
