556 



BALCH— THE COUDERSPORT ICE MINE. 



the rock cracks leading to it. And the reason ice does not form then 

 is that at that time the water is all frozen up on the outside. But 

 when the thaws of spring melt the outside ice and snow into water 

 this flows into the glaciere and its communicating rock cracks and, 



Fig. 2. Coudersport Ice Mine. Ice curtain and ladder covered with ice. 



meeting the cold air within, congeals. The only effect of the heat 

 of summer is slowly to melt the ice. 



This theory is not a new one. In essence, it is found in the earliest 

 account we have of a glaciere, a visit to Chaux-les-Passavant, pub- 

 lished in 1586, in which the author, Benigne Poissenot, a Paris 

 lawyer, says : 



After having thought over in my mind the cause of this antiperistase, I 

 could find none other but this: to wit, that as heat dominates in summer, the 



