But be this as it may, the difference between the
porous ice of the upper region of the glacier and the compact blue ice
of its lower track seems to me evidence direct that at times the whole
mass must assume the rigidity imparted to it by a temperature inferior
to the freezing-point. We know that at 32 deg. Fahrenheit, regelation
renders the mass continuous, and that it becomes brittle only at a
temperature below this. In other words, the ice can break up into a mass
of disconnected fragments, such as the capillary fissures and the
infiltration-experiments described in my "Systeme Glaciaire," show to
exist, only when it is below 32 deg. Fahrenheit. If it be contended that ice
at 32 deg. does break, and that therefore the whole mass of the glacier may
break at that temperature, setting aside the contradiction to the facts
of regelation which such an assumption involves, I would refer to Dr.
Tyndall's experiments concerning the vacuous spots in the ice.
[Illustration]
Those who have read his startling investigations will remember that by
sending a beam of sunlight through ice he brought to view the primitive
crystalline forms to which it owes its solidity, and that he insisted
that these star-shaped figures are always in the plane of
crystallization.
Pages:
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309