272 
INTERNAL STRUCTURE AND 
were invariably frozen up in newly formed water- 
ice, entirely different in its structure from the 
surrounding glacier-ice. This freezing could not 
have taken place, did the mass of the glacier 
never fall below 32° Fahrenheit. And this is 
not the only evidence of hard frost in the interior 
of the glaciers. The innumerable large walls of 
water-ice, which may be seen intersecting their 
mass in every direction and to any depth thus 
far reached, show that water freezes in their in- 
terior. It cannot be objected, that this is merely 
the result of pressure ; since the thin fluid seams, 
exhibited under pressure in the interesting ex- 
periments of Dr. Tyndall, and described in his 
work under the head of Crystallization and In- 
ternal Liquefaction, cannot be compared to the 
large, irregular masses of water-ice found in the 
interior of the glacier, to which I here allude. 
In the absence of direct thermometric obser- 
vations, from which the lowest internal temper- 
ature of the glacier could be determined with 
precision in all its parts, we are certainly justi- 
fied in assuming that every particle of water-ice 
found in the glacier, the formation of which can- 
not be ascribed to the mere fact of pressure, is 
due to the influence of a temperature inferior to 
32° Fahrenheit at the time of its consolidation. 
The fact that the temperature in winter has been 
proved by actual experiment to fall as low as 28° 
