NATURAL PHILOSOPHY. 191 



since discovered two wells in that village, 60 feet deep, which freeze up. 

 They are situated a short distance from the Susquehanna, and below its bed. 



In the discussion which followed, Professor Guyot said he had observed on 

 the Jura a number of ice caves. One was 60 feet deep. At the opening, 

 columns of ice had formed, falling to the bottom. His explanation was, that 

 in places nearest of access to the snows in winter, we are sure to find ice in 

 summer, if the quantity of snow was large enough. In the case of Mr. 

 Brocklesby 's well, the place admits large quantities of snow, which melts, but 

 not readily, because it is not accessible to the sun. It therefore goes through 

 the process which the glaciers of the Alps undergo. The snow freezes again 

 during the night, after being partly melted ; and we have the formation of the 

 glacier without movement. It is exactly the same in this as in the Alps. 



Professor W. B. Rogers cited similar occurrences in a range of mountains 

 composed of a porous sand rock in Southern Virginia. But he could not see 

 that any accumulation of snow at the bottom of a well should generate ice 

 about its sides. He could, however, well imagine this condition of things, 

 viz : That if the atmosphere became very much chilled, the well becomes the 

 recipient of the coldest air in the neighborhood, on account of its greater 

 specific gravity. The temperature of the weU in such case becomes perfectly 

 abnormal, and because of the bad conducting power of its materials retains 

 the cold. This was his explanation. 



Professor Denison Olmstead held that very cold air exists in the interior of the 

 earth, which may find a ventilating shaft in the well. In ice houses wastage 

 is prevented by allowing a current of air to pass freely, rather than to permit 

 the ice to be closely housed. Liquefaction after congelation is a very slow 

 process. 



Professor Agassiz questioned whether any very low temperature exists in ice 

 resting upon other bodies. When attempting to ascertain the 'temperature 

 of the Glaciers, by running a thermometer ten feet below the surface, he had 

 failed to find anything but a fraction of a degree below 32. A self-register- 

 ing thermometer, sunk 20 feet below the glacial surface, remained there all 

 winter, and indicated no such temperature as we would be ready to admit as 

 possible under influences so intensely cold. 



Professor Henry said that during the past whiter he had been struck with the 

 fact that pieces of ice wrapped in a cloth were frozen to it, although not one 

 out of the several thermometers would go down to 32. It appeared from 

 this, as from the old observation of La Place, who found that the ice surround- 

 ing the worm through which they were transmitting gases was soon frozen to 

 the worm, that melting ice produced a certain degree of cold* 



Professor Guyot stated that the ice caves which he had referred to were 

 3,000 feet above the level of the sea^ where the quantity of falling snow was 

 very great. 



Professor Brocklesby could not see the analogy between an ice cave and a 

 frozen well. The temperature of deep wells generally being about the mean 

 temperature of the place ; the temperature of wells in Owego would not vary 

 much from 46 or 47. He did not think that the phenomenon had been 

 explained. 



