Glacières; or, Freezing Caverns

by Edwin Swift Balch

“The snow slope at the mouth of a cave offers some protection against the rays of the sun, especially if it is no longer white, but covered with all sorts of dirt.”

“The larger the mass of ice, the longer is its duration.” “A certain thickness to the roof is of importance in preserving the ice. If it is less than 8 meters, then it is well if it is covered with outside vegetation.”

I entirely agree with these dicta of Professor Fugger.

In 1893, Fugger writes: "The peculiar readings of temperature, which I made in August 1877, in the Kolowratshöhle, namely on the 13th at 12 M., 0.5°, on the 15th at 4 P. M., 0.35°, on the 23d at 10 A. M., 0.12°, on the 26th at 10 A. M., 0.17°, and on the 30th at 2.15 P. M., -0.10°, I think I can attribute to the workings of the winds. In the observations themselves there could scarce be an error. All five observations were made at the same place, with the same thermometer, after at least half an hour’s exposure. In the time from the 13th to the 30th of August, the temperature minimum in the town of Salzburg, was 12°; before the 30th were several cloudless nights. During the whole of August scarcely any but southeast and northwest winds were blowing. The Kolowratshöhle opens in a rock wall to the east; the above named winds therefore affected during the entire month the entrance to the cave and may have produced a lively evaporation in the cave, through a sort of sucking up of the cave air, and thus have created the rather decided cooling off of 0.6° within seventeen days."

This statement, coming from Professor Fugger, deserves particular attention, because it would go to show: first, that the air in the Kolowratshöhle, a sackhöhle with only one entrance, is only apparently stagnant in summer and not really so; and second, that evaporation may act to a limited extent in a cavern where there is almost no running water.

Captain Trouillet, in 1885, published a paper about Chaux-les-Passavant. He found that when it was colder inside than outside, the internal air was nearly cut off from the outside; when it was coldest outside there was a lively disturbance. He called these two classes périodes fermées and périodes ouvertes. He says: “The duration of a closed period is measured then on the curves [of a maximum and minimum thermometer] of the interior temperatures, between a minimum and the following maximum; that of an open period is between a minimum and the preceding maximum. One can thus count from the 25th November to the 31st December 25 open periods of a total duration of 200 hours or 8 times 24 hours: which gives for each a duration of 7-1/2 hours. The shortest lasted 2 hours and the longest 16 hours. During the same interval, the closed periods numbered 26, making a total duration of about 28 days; the longest, which lasted from the 3d to the 8th December, was 126 hours long.”

Trouillet also says: “From the 23d to the 30th December, the grotto was completely isolated from the external air, and yet during three consecutive nights, the interior had three marked chills. Such is the phenomenon whose cause can only lay, in our opinion, in the introduction of the dry air driven to the cave by the winds between north and east. This air on entering comes in contact with the ice and the humid roof of the cave; it saturates itself in producing a formation of vapors, and therefrom a consumption of heat which may be considerable.”

There are some discrepancies in this last paragraph which must be noted, for the reason that Trouillet’s observations are so valuable. He does not mention having seen the vapors himself, in fact the production of these vapors seems only an inference. Nor is it easy to understand how the grotto could be “completely isolated from the external air” if the phenomenon lay “in the introduction of the dry air driven to the cave by the winds north and east.”

Dr. B. Schwalbe, in 1886, wrote that “all my observations point to the fact that the rock is the cooling factor in summer, and that the cold goes out from it.” He says also that "when I saw for the first time the little cave of Roth, which was filled with fairly numerous ice formations, it was precisely the smallness of the volume of air and the strange appearance of the ice which made the simple cold air theory seen insufficient, nor could I later, by widening the theory and observing the localities from the basis of DeLuc’s theory, accept it. It always seemed by all my observations that in the rock there must be a lasting source of cold. There must be a cause present, which prevents the rapid warming of the cave wall through the temperature of the ground, which also keeps the stone cool in summer and induces the main ice formation in the spring." He also hints that Mr. Lowe’s compressed air theory may be the correct one. Dr. Schwalbe’s work, Über Eishöhlen und Eislöcher, is one of the four or five most important contributions to glacière literature, and his opinion is entitled to great respect on account of his many observations.