Wyville Thomson—General Ocean Circulation. 359 
very bad conductor, so that the cold of winter cannot penetrate 
to any great depth into the mass. The normal temperature of 
the surface of the earth’s crust, at any point where it is unin- 
thickness—not much less than a quarter of a ton on the square 
Inch. It seems, therefore, probable that under the pressure to 
which the body of ice is subjected a constant system of melt- 
or submerged. 
I should think it probable that this process, or some modifi- 
Cation of it, may be the provision by which the indefinite 
accumulation of ice over the antarctic continent is preven 
and a certain uniformity in the thickness of the ice-sheet 
maintained—that in fact ice at the temperature at which it is 
i contact with the surface of the earth’s crust within the 
antarctic regions cannot support a column of itself more than 
1.400 feet high without melting. It is suggested to me by 
Professor Tait that the thickness of the ice-sheet very probabl 
depends upon its area, as the amount of melting throug 
ueezing and the earth’s internal heat, will depend upon the 
facility of the escape of the water. The problem is, however, 
an exceédingly complex one, and we have perhaps scarcely 
sufficient data for working it out. ae 
e Fauna of the Deep Sea,—I can scarcely regret that it is 
Utterly impossible for me on this occasion to enter into any 
details with regard to the relations of the abyssal fauna, the 
department of the subject which has naturally had for me the 
Steatest interest. Recent investigations have shown that there 
18 no depth limit to the distribution of any group of gill-bearing 
Marine animals. Fishes, which, from their structure and from 
What we know of the habits of their congeners, must certainly 
