236 DISCUSSIONS IN CLIMATOLOGY. 



the outer side, but to hold back or prevent such a 

 motion taking place in the ice on the inner or poleward 

 side. As such an expansive force is assumed to act in 

 every portion of the mass, it follows that the nearer the 

 outside of the sheet the more rapidly will the ice 

 move, and consequently the thinner will the sheet 

 become. 



The Greater Thickness of the Sheet at the Pole inde- 

 pendent of the amount of Snowfall at that place. — It 

 has been proved that unless the Antarctic ice were 

 thickest at the Pole and thinnest at the edge, motion 

 could not take place. It follows, therefore, that how- 

 ever much the snowfall at the edge and other places 

 may exceed that at the Pole, or centre of dispersion, 

 the ice must always be thickest at the centre. For 

 however small may be the snowfall, and consequent 

 amount of ice formed annually at the Pole, snow and 

 ice must of necessity continue to accumulate year by 

 year till the sheet becomes thickest there. The ice at 

 the Pole could not move out of its position till this 

 were the case. Supposing there were no snow what- 

 ever falling at the Pole, and no ice being formed there, 

 still the sheet would be thicker there than at the edge. 

 For in this case the ice forming at some distance from 

 the Pole all around would now back, as has already 

 been shown in Chapter V., towards the centre, and con- 

 tinue to accumulate there till the resistance to the 

 inward flow became greater than the resistance to the 

 outward ; but this state would not be reached till the 

 ice became thickest on the poleward side. 



We have no reason to believe, however, that the 

 quantity of snow falling at the Pole is not great. 

 " One thing we know," says Sir Wyville Thomson, 

 " that the precipitation throughout the Antarctic area 

 is very great, and that it is always in the form of 



