78 



The shaft was then covered over with plank, and upon the plank 

 shavings were placed, to intercept communication as much as possi- 

 ble between the shaft and the external atmosphere. 



A few rods north-easterly from the gravel ridge in which the cold 

 well and the two shafts were sunk, two wells have been sunk during 

 the summer, both through compact clay with narrow seams of fine 

 sand. One of them, about fifteen feet deep, contains water; the 

 other, about forty feet deep, is dry." 



Although we do not feel that we have been able to remove all 

 doubts as to the true theory of the phenomena of the frozen well, 

 still we incline to believe that the freezing is due. to the nature of 

 the conducting medium in which the well exists, and that the wave of 

 heat in the summer months is not adequate to overcome the cold of 

 the longer cold months, while the uncommonly severe winters of 1856 

 and 1857 may have lowered the temperature of the rocky masses of 

 boulders, so that the wave of summer heat has not yet been able to 

 reach the frozen mass, which, once congealed, would resist thawing on 

 account of the slow conduction of ice. It should also be remembered 

 that water does not conduct heat downwai'd readily, though it does 

 upward by convection.* 



The existence of beds of boulders in other cold and frozen wells, 

 as in the one of Tioga, N. Y., seems to point to the same solution. 



The ice in the Brandon well forms some time in November, and it 

 remains until September, thus showing only a brief period when 

 the temperature of the bottom of the well is above the freezing tem- 

 perature, while the great mass of boulders remains much below it ; 

 the well, being more exposed, receives the first warmth by conduction 

 of its walls exposed to the air. 



Among the hypotheses which have been offered to account for the 

 phenomena of the frozen wells, are the following : — 



1st. — The penetration of cold currents of air through the boulder 

 stratum. This hypothesis is without any foundation, because there 

 are no open spaces, and the boulders are closely cemented together 

 by being imbedded in clay and sand; and also because the fact is 

 ascertained, that there are no currents of air moving in the mass, or 



* The familiar experiment of boiling water upon the surface of a cake of ice 

 without melting- it, and that of boiling water at its surface, by meaus of a plate 

 of hot iron placed over it, while the water below is not heated, illustrates this 

 statement. 



It is true that the maximum density of water is at 39° Fah., and that it sinks 

 when at this temperature in water that is either warmer or colder, but this 

 movement is limited to a few degrees of temperature, Ice, having its particles 

 fixed, does not allow of the varying of heat by convection, as it is called, and 

 is a very bad conductor of heat, as is obvious to all who observe a cake of it 

 exposed to a warm atmosphere. 



