THE QUARTERLY 
JOURNAL OF SCIENCE. 
JANUARY, 1879. 
I. ON THE THICKNESS OF THE ANTARCTIC 
ICE, AND ITS RELATIONS TO THAT OF 
THE GLACIAL EPOCH. 
By James Croll, LL.D., F.R.S., 
Of H.M. Geological Survey. 
cz± 
I N a recent work* I have endeavoured to show that the 
thickness of the ice on the Antarctic continent must 
^ be far greater than is generally supposed ; that what- 
ever be its depth at the edge of the continent, where it 
breaks up into bergs, the thickness at the Pole or centre of 
dispersion must be enormous. 
Since the publication of my work, however, Sir Wyville 
Thomson, Director of the Scientific Staff of the Challenger 
Expedition, in a ledture on the condition of the Antarctic 
regions, delivered at Glasgow, has come to a totally different 
conclusion. His conclusion is based chiefly on considera- 
tions relating to the principle of regelation and the physical 
nature of ice ; and the following quotation from his lecture 
will show his views on the subjedt : — 
“ There is one point in connection with the structure of 
icebergs which is of great interest, but with regard to which 
I do not feel in a position to form a definite judgment. It 
lies, however, especially within the province of a distin- 
guished professor in the University of Glasgow, Dr. James 
Thomson, and I hope he will find leisure to bring that 
knowledge to bear upon it which has already thrown so 
much light upon some of the more obscure phenomena of 
ice. I have mentioned the gradual diminution in thickness 
“ Climate and Time, Chap. XXIII. 
VOL. IX. (N.S.) 
B 
