EXPERIMENTS IN ICE MOTION. 
In a previous study the author became convinced that a defi- 
nite relation exists between certain deposits of glacial débris and 
the topography of the surface over which the ice from which 
they were deposited had just passed. It seemed that this rela- 
tionship could only be explained by the existence of differential 
movements or currents in the ice bottom, and it was to determine 
the existence of these and, to as great an extent as possible, 
their nature, that the following experiments were undertaken. 
Much discussion has taken place over the method of motion 
in glaciers and the condition of the basal portion of a thick bed 
of ice, such as a continental glacier. The upper parts of glaciers 
are known to be practically rigid, while the basal portions, as far 
as can be judged from the resultant topography, is possessed of 
differential movements, such as might take place in a viscous body. 
Whether the mobility of the bottom is caused by regelation, 
granulation or true viscosity, the currents would be the same and 
it was these alone that the author attempted to investigate. 
Under the assumption that the currents were such as could 
take place in a viscous body, the substance chosen to experi- 
ment with was wax or paraffine in which was dissolved a quantity 
of refined petroleum to lower the melting point. The paraffine 
was melted and allowed to cool to a temperature such that it 
would just give under its own weight, great care being taken to 
keep it of an equal temperature and softness throughout The 
wax was than forced through long, narrow boxes, open at both 
ends, by means of closely fitting plungers, and caused to pass 
over obstructions of various kinds placed in its path. It was 
then allowed to cool in the box and sawn or sliced into sections. 
The boxes used were of varying lengths and generally about 
twice as high as broad, allowing for a vertical play of currents 
918 
