The Flow of Glaciers. — Upham. 17 
a continuous mass. Forbes demonstrated that the differential 
movement together of the various lateral, central, bottom, and 
surface portions of a glacier is like the now of a viscous body, 
and that the blue and white veining is dependent on the vis- 
coid motion. Tyndall, impressed by the incompatibility of 
true viscosity with the formation of crevasses, taught that 
the ice yields to the force of gravitation by a constant and 
exceedingly minute fracturing throughout all its mass, atten- 
ded with refreezing or revelation, which continuallj r mends 
again the imperceptible fractures after an infinitesimal slid- 
ing of the broken surfaces one past the other whereb}^ the 
seemingly viscous flow takes place. 
German and French observers and theorists, including 
Hugi in lN4ri, and subsequently Grad and Dupre, Bertin, 
Klocke, Forel, and Hagenbach, have specially noticed and 
studied another very interesting and particularly character- 
istic feature of glacier ice, namely, its granular structure. 
Within the past few years the results of these investigations. 
in their bearing on the explanation of the motion of glaciers. 
have been brought to the attention of English-speaking 
glacialists by Sir Henry' Howorth;* and last year an impor- 
tant paper on this subject, giving careful observations and 
drawings of the granular structure, and indicating its prob- 
able relation to the physical conditions of glacial Mow, has 
been jointly published by Messrs. R. M. Deeley and George 
Fletcher. f The glacier granules originate with the consoli- 
dation of the firii or neve to form compact ice, and. though 
doubtless constantly undergoing changes, they continue recog- 
nizable, by proper optical examination, in all the mass of the 
glacier, through its vicissitudes of pressure, differentia] flow, 
veining, fracture, and regelation, to the end of their course 
far below the snow-line, after many years or even several 
centuries of very slow advance from near the mountain sum- 
mits to the limit of the glaciers amid the forests, fields, and 
gardens of the valleys. 
Purpose ok this Paper. 
In the present paper inquiry is made concerning the in- 
fluence of the sedimentary stratification of the firn or neve to 
*The Glacial Nightmare and the Flood. L893, vol. u, pp. .v_>s :>:;•_>. 
^Geological Magazine. IV. vol. n. pp. L52 162, with nine figures 
April. 1895. 
