1881 .] 
165 
[Slialer. 
themselves, and study their variations that occur there, rather 
than in the much more condensed ice which lies below the snow 
line. 
I am satisfied that very good foundations for future enquiries 
may be found in the study of the variations that take place with- 
in the neve. A system of bench marks on the exposed cliffs that 
are almost always to be found within the upper snow-fields where 
the rock is too steep for the winter snow to remain, might be 
used to record successive observations ; a succession of observa- 
tions on the height of protruding rocky points with reference to 
the movement of stakes planted in the neve, would give data 
for extracting the changes of its height and speed of movement 
from year to year, and from decade to decade. There can be 
little doubt that these observations could be correlated with 
the seasonal changes of snow fall, and we should know when 
to expect advances and recessions of the ice, except so far as these 
might be affected by the variations of heat and rainfall. Some- 
thing almost as useful could be done by taking the depth of the 
neve-ice where it pours over the upper seracs into the body of 
the lower glacier. This point is so geographically distinct, that 
measurements of its depth and rate of motion could easily be ob- 
tained. Measurements of this description will have a definite 
value for students of glaciers, but any further attempts to cor- 
relate the variations of temperature in former years with the 
advance and recession of the ice, without reference to the rate 
of motion or the length of glaciers, seems to me a hopeless waste 
of labor. 
In the following propositions the foregoing and some other evi- 
dent considerations concerning the movement of glaciers as bear- 
ing on the problem of climatal changes are presented in a con- 
densed form. 
1. The position of the terminal point of any glacier depends 
upon a complicated equation, in which the principal factors are 
the amount of snow which has fallen in remote times upon the 
neve district, and the rate of melting of the ice when it comes 
below the snow line. 
2. Glaciers differing in length, in declivity of bed, in exposure 
to sun, etc., will express the effects of these variations by changes 
