Dr. B. F. Harrison on Solution of Ice on Inland Waters. 53 
or 86°. After the last observations, I did not visit the lake for 
a long period, but I believe the ice disappeared early in March. 
Such a result might have been anticipated as the temperature of 
the air had already risen several degrees above the freezing point 
and the water beneath the ice (which was nowhere broken) con- 
tained heat sufficient to dissolve one and three-fourths times as 
much ice as then covered its surface. 
In considering the causes of the phenomena here recorded, it 
becomes important to take into consideration the temperature of 
the earth’s surface in this latitude, and the variations of tempera- 
ture for a short distance below the surface. The mean tempera- 
ture of the earth at all depths short of one hundred feet is very 
Ww. 
UNncoy 
we 48 covered the surface of the lake, and all agitation of its 
ters has ceased, the earthy bed still continues to impart its re- 
