8o Mr. H. H. Howorth on 



freezing of the water in the capillaries of a glacier is very- 

 slight, and, further, that as the glacier gets consolidated, 

 these capillaries gradually disappear, and with their dis- 

 appearance disappears also the prinium mobile postulated 

 by the dilatationists. He also urged that if the dilatation 

 theory were true, the maximum of motion in a glacier 

 should be greatest in the evening, when the water in 

 the capillaries freezes, or in the morning when it should 

 melt, which is not found to be the case (Heim, Gletscherkunde^ 

 294 — 5, see also Mousson Gletscher der Jetztzeit^ 155, etc.). 



Mr. Bonney, in regard to this theory, says it fails to 

 explain the motion of glaciers in the coldest winters, and 

 the fact that it is not liable to any marked change when 

 there is a sudden alteration in the temperature of the 

 surrounding air. Nor have its advocates proved the exist- 

 ence of the fine capillaries necessary for it to work 

 upon. On the contrary, Huxley and Tyndall shewed that, 

 except at the surface, a glacier is formed of compact ice 

 impenetrable to coloured liquids. 



In addition to these various converging and irresistible 

 difficulties, the dilatation theory does not account for the 

 fact that the motion of glaciers has been shewn to exist in 

 the deep blue ice, where there are no fissures, as well as in 

 the superficial ice. Nor for the fact of the continuously 

 differential motion which has also been shewn to pervade 

 all parts of the glacier. It has long been discarded, and 

 was, I believe, discarded by its greatest champion, Agassiz, 

 before he died. 



We will now turn to a development of the dilatation 

 theory, which still has some supporters. 



As early as 1822 Hugi had noticed the granular structure 

 of glacier ice to which I have referred, and he urged that 

 if we examine the most compact ice of glaciers when it is 

 melting, this granular structure is displayed. (Hugi, Der 

 Gletcher^ etc., 8, etc.) He further showed that the size of these 



