Tkaill. — Antarctic Exploration. 473 



such extreme rigour there can be no waste by thawing, and that 

 such an ice-plain, or a circumpolar continent, must increase in 

 height by the amount of the yearly snowfall. Let us see what 

 this would lead to ! Supposing that no more genial climate has 

 existed there for the short geological period of a quarter of a 

 million years, and that the snowfall increased the height of the 

 ice by only 2 feet yearly, which would be equivalent to less than 

 28-0 inches of rainfall, a simple calculation will show that by 

 this time the ice would form a stupendous mountain, in com- 

 parison with which the huge bulk of the mighty Himalayas 

 would be a trifle — in fact, the ice-mountain would be eighteen 

 times their height. Clearly, then, granting that our theoretic 

 ice-mountain could not sustain its own weight, there must be 

 yearly waste roughly commensurate with yearly nourishment. 

 I think there can be little doubt that the ice- sheet is prevented 

 from increasing in size and advancing towards us chiefly by the 

 northern edge breaking off and floating away in the shape of 

 icebergs, and by the thawing of the undersurface, due to some 

 heat derived from the contiguous land or water, aided by the 

 effects of pressure and friction, and yet that these combined 

 causes would be comparatively powerless to hold it in check 

 without the assistance of oceanic currents. 



With regard to the feeding. Boss remarks : " Whether Parry 

 Mountains again take an easterly trending and form the base to 

 which this extraordinary mass of ice is attached must be left 

 for future navigators to determine." Special interest attaches 

 to Parry Mountains from their being the southernmost land yet 

 discovered. Over the edge of the westerly portion of the barrier 

 their lofty summits could be seen stretching far away to the 

 southward. Although at right angles to the barrier edge, I do 

 not see why they may not form the " base," without the suppo- 

 sition of an " easterly trending" being necessary. The ice, after 

 descending from their slopes, though pushed off chiefly to the 

 eastward, must surely be sufficiently plastic to spread north- 

 wards as well — the greater the resistance to its easterly advance, 

 the more must it be pushed to the northward. Whether the 

 chief nourishment is by glaciers from the Parry Mountains, 

 (supposing that the ice-sheet is connected with no others,) or 

 from the snowfall on its own surface, may depend chiefly on the 

 comparative areas of that surface and of the eastern slopes of 

 the range. I am inclined to think that the glaciers play a 

 subordinate though important part. 



That motion should be imparted to such a vast mass by ice 

 descending from the mountains may seem hard to credit, espe- 

 cially if we suppose the sheet to rest chiefly on land, and con- 

 sider the enormous friction where in contact with the rocks 

 below ; but perhaps nothing could so efficiently act the part of 

 a lubricant in lessening the friction as interposed water derived 



