Horace Bénédict de Saussure, the great Swiss scientist and mountaineer, in 1796, published a number of observations about cold current caves in various parts of the Alps. He found that in summer the air blows outward at the lower end, and that in winter it draws inward. His explanation is that in summer the colder air in the tube is heavier than the outside air and displaces it by gravity; while in winter the rupture takes place in the other direction, since the column within the tube is warmer than the outside air and therefore is pushed upwards by the heavy air flowing in. He concludes that evaporation due to the air passing internally over moist rocks suffices to explain the phenomenon of low temperatures and that such caves have a rather lower temperature in the Alps than in Italy owing to the greater natural cold of the Swiss lake region. An experiment of his is worth mentioning. He passed a current of air through a glass tube, 2.5 centimeters in diameter, filled with moistened stones, and found that the air current which entered with a temperature of 22.5° came out with a temperature of 18.75°, that is with a loss of 3.75° of heat. Robert Townson, LL.D., in 1797, published an account, perhaps the first in English, of a glacière cave. He says of Szilize: "Ice I truly found here in abundance, and it was mid-summer, but in a state of thaw; the bed of ice, which covered the floor of the cavern was thinly covered with water and everything announced a thaw. I had no need to use my thermometer: however I placed it in the ice and it fell to 0° of Réaumur: I then wiped it and placed it in a niche in the rock, at the furthest part of the cavern, a yard above the ice and here it remained near an hour: when I returned I found it at 0°. * * * Everything therefore, ice, water and atmosphere in the neighborhood had the same temperature, and that was the temperature of melting ice: 0° Réaumur.