5. It is well known that sound is propagated far more freely in Polar regions than with us. When the cold was great, we could hear conversations, carried on in the usual tone of voice, distinctly at the distance of several hundred paces. Parry and Middendorf both assert that the voice is more audible at a distance in cold weather. The propagation of sound seems to find less hindrance from the irregular masses of ice and cushions of snow, than from the curtains of our woods and the carpets of our vegetation. In the mountainous districts of Europe many of the characteristics of Polar regions, besides intense cold, are met with; yet it is a fact, that the report of a gun can scarcely be heard in those situations. Cold, however, can scarcely be regarded as the essential condition of this phenomenon; for the propagation of sound, though in a less striking degree, may be observed even in the summers there.[36] It would seem rather that the amount of moisture in the atmosphere has a more decided influence in the production of this phenomenon. 6. When the snow becomes hard as rock, its surface takes a granular consistence like sugar. Where it lies with its massive wreaths frozen in the form of billows, our steps resound, as we walk over them, with the sound as of a drum. The ice is so hard that it emits a ringing sound; wood becomes wonderfully hard, splits, and is as difficult to cut as bone; butter becomes like stone; meat must be split, and mercury may be fired as a bullet from a gun.[37]