G. F. Becker—Temperature and Glaciation. 167 
Art. XX.—On the Relations of Temperature to Glaciation ; by 
GEORGE F. BECKER. 
_THE theory of a Glacial period has always presented great 
difficulties. Agassiz acknowledged their existence from the 
question, a lower temperature was requisite. This view has 
recently been sustained by Mr. G. K. Gilbert in opposition to 
the arguments presented by Prof. Whitney. Since it is evi- 
dent that the question cannot be settled without further discus- 
Sion, it is probably desirable to consider it from as many points 
or view as possible. Of these one will be here presented. 
If the sun and earth are members of a system now under- 
going a uniform loss of heat, it appears certain that the forma- 
ion of glaciers must be limited to a distinct period in the 
earth’s history. So long as the temperature nowhere sank, 
the earth’s surface would preclude the formation of glacial ice, 
for the rate of evaporation diminishes more rapidly than the 
temperature, The entire quantity of water existing in satu- 
rated aqueous vapor at a temperature of minus 20° C. is a little 
less than would be precipitated from aqueous vapor of a temper- 
. The present time lies between the ex- 
treme periods indicated, and it is known by observation that 
glaciers are in process of formation. It is certain, therefore, 
