Now that water pervades this net-work of fissures in the glacier to a depth not yet ascertained, my experiments upon the glacier of the Aar have abundantly proved; and that the fissures themselves exist at a depth of two hundred and fifty feet I also know, from actual observation. All this can, of course, take place, even if the internal temperature of the glacier never should fall below 32 deg. Fahrenheit; and it has actually been assumed that the temperature within the glacier does not fall below this point, and that, therefore, no phenomena, dependent upon a greater degree of cold, can take place beyond a very superficial depth, to which the cold outside may be supposed to penetrate. I have, however, observed facts which seem to me irreconcilable with this assumption. In the first place, a thermometrograph indicating -2 deg. Centigrade, (about 28 deg. Fahrenheit,) at a depth of a little over two metres, that is, about six feet and a half, has been recovered from the interior of the glacier of the Aar, while all my attempts to thaw out other instruments placed in the ice at a greater depth utterly failed, owing to the circumstance, that, after being left for some time in the glacier, they 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 deg. 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 interior. It cannot be objected, that this is merely the result of pressure; since the thin fluid seams, exhibited under pressure in the interesting experiments of Dr. Tyndall, and described in his work under the head of Crystallization and Internal 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 observations, from which the lowest internal temperature of the glacier could be determined with precision in all its parts, we are certainly justified in assuming that every particle of water-ice found in the glacier, the formation of which cannot be ascribed to the mere fact of pressure, is due to the influence of a temperature inferior to 32 deg. Fahrenheit at the time of its consolidation. The fact that the temperature in winter has been proved by actual experimentation to fall as low as 28 deg. Fahrenheit, that is, four degrees below the freezing-point at a depth of six feet below a thick covering of snow, though not absolutely conclusive as to the temperature at a greater depth, is certainly very significant.