190 REVIEWS 
In the latter part of the paper he questions the adequacy of the energy 
available for glacial movement. Instead, however, of following carefully 
the postulates of the granular theory, he substitutes postulates of his own 
which any advocate of the theory would repudiate. For example, instead 
of trying to estimate the value of the gravitative pressure and the insolation, 
direct and indirect, which are the sources of the energy of movement 
assigned by the sponsors of the theory, he discusses the value of the im pact 
of the moving granules, and seems seriously to regard the energy repres- 
sented by the velocity of the granules as the total energy available! 
Preliminary to an effort to show that there are narrow limits to the 
possibilities of glacial advance under the granular theory, the author 
says: ‘‘ According to this theory, as it is stated by its sponsors, the elonga- 
tion of a glacier is due primarily to the relief from compression afforded 
by the intergranular spaces;” and on this basis he proceeds to discuss the 
limits of the compression of the granules and the insufficiency of the inter- 
granular spaces. His special sponsor for the theory, however, says, after 
detailed exposition: ‘‘These considerations lead to the view that move- 
ment takes place by the minute individual movements of the grains upon 
one another.” It is difficult to find an excuse or palliation for such 
substitutions of propositions, indefensible on their face, for the propositions 
actually advanced by the sponsors of the granular theory. Ii a subject 
so infelicitous for academic treatment as the minute dynamics of glaciers 
is chosen at all, it is natural to expect it to be treated with academic fidelity. 
EnCre 
