558 BALCH— THE COUDERSPORT ICE MINE. 



larger glacieres of Europe the size of the glaciere permits a volume 

 of freezing cold air to remain over into the spring sufficient for the 

 work of refrigeration. But in certain cases, where the ice of the 

 glaciere is far back from the mouth, and where the phenomena are 

 less patent, freezing cold air entering the glaciere from the rock 

 crevices above it may well be an auxiliary, insufficiently noticed up 

 to now, in the formation of the ice. Indeed, the ice stalactites which 

 issue from holes in the roof or the walls of caverns may well obtain 

 from their own rock crevices instead of from the main body of the 

 glaciere some at least of the cold which causes their formation. 



Another factor which surely has an influence on the ice at Couders- 

 port is an artificial one, namely, the wooden floor and the trap door. 

 These prevent almost entirely radiation and they probably have a 

 considerable effect on the ice, according to whether the trap door is 

 left shut or open. If the trap door is closed or open in winter, it 

 would militate against the cold air descending into the shaft and vice 

 versa; if it is shut or open in summer, it would help to prevent the 

 cold air in the shaft from warming up and vice versa. When I 

 entered the door in the fence the trap door was wide open, but the 

 guardian said it was usually kept closed. Apparently, therefore, it 

 is effective up to a certain point, much as is a door in an artificial 

 refrigeratoi and I have no doubt that the wooden floor and trap 

 door add materially in keeping the temperature low. 



Of one thing, however, I feel very sure, and that is that the 

 Coudersport Ice Mine is a true glaciere and obeys the identical nat- 

 ural laws which hold sway in all glacieres. And I base this unscien- 

 tifically dogmatic statement on the visits I have made in past years 

 to some forty other glacieres. Reduced to its simplest formula, the 

 law of glacieres is that the cold of winter furnishes the cold, the 

 thaws of spring furnish the water, and the heat of summer melts the 

 ice. The Ice Mine has its local peculiarities, but every glaciere has 

 these. And although, when compared with some of the great gla- 

 cieres of Europe, with Chaux-les-Passavant. Saint Georges, the 

 Schafloch, the Kolowratshohle, Dobsina, and several others, the 

 Coudersport Ice Mine is but a small glaciere, yet it is the most im- 

 pressive one known in the eastern United States, the one which 



