THE SWEDEN VALLEY ICE MINE
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The belief of the peasants is founded on the fact that they scarcely ever go to any cave except when some tourist takes them with him, and, therefore, they rarely see one in winter, and their faith is not based on observation. It is, however, founded on an appearance of truth: and that is on the fact that the temperature of glacière caves, like that of other caves or that of cellars, is colder in summer than the outside air, and warmer in winter than the outside

Professor Thury tells a story to the point. He visited the Grand Cave de Montarquis in midwinter. All the peasants told him there would be no use going, as there would be no ice in the cave. He tried to find even one peasant who had been to the cave in winter, but could not. He then visited it himself and found it full of hard ice.
While the writer does not claim, as these peasants, that the heat of summer is the direct and only cause of the formation of ice, he does hold that it is an indirect cause and that the ice to be seen in the Sweden Valley Ice Mine is formed after the temperature outside the mine is far above the freezing point, and it is when the temperature outside is the highest that the ice is formed the most rapidly. The cause of this will be explained shortly.