290 Prof. Bischof on tJte Temperature of 



and that of the air, 6 fathoms from the verspunden, 60°.8 to 

 6P.02; and on the 20th March, also from five perfectly accor- 

 dant observations, the temperature of the water 61°.56, and 

 that of the air, at the same place as before, 60°.23. The dif- 

 ference of 0°.09 is within the error of observation. It is cer- 

 tain that the enclosed body of water must have assumed the 

 temperature of the surrounding rock ; and in Reich's opinion 

 there can be but two causes which could occasion a difference 

 between them. The first is the escape of some of the water 

 through the verspunden, and its replenishment from above; 

 the second is the continued change of air before the verspunden. 

 But both of these influences can be but inconsiderable, for, as 

 we have already remarked, a very small quantity of water 

 makes its escape, and the enclosed water is separated from the 

 air by a mass of wood of 6 feet in thickness. Further, these 

 two circumstances could only tend to diminish the temperature 

 of tile water, as the water was replenished from above, and the 

 air at the end of the summer, as well as at the end of the win- 

 ter, was colder than the water, although the difference was 

 smaller in the former case than in the latter. 



From these observations, Reich calculated an increase of 

 temperature of 2°.25 in 136 — 11.3 feet, which is very much 

 more rapid than the mean deduced from the observations in 

 the mines of the Erzgebirge. This adds some weight to the 

 supposition expressed above, that the mines are by degrees re- 

 duced in temperature by the entrance of cold air and water 

 from the surface. 



Later observations of Phillips,* in a shaft of unusual depth 

 recently sunk at Monk-Wearmouth, near Newcastle, gave re- 

 sults which corresponded very nearly with those in the Erzge- 

 birge, All external influences could only have caused a depres- 

 sion, but not an elevation, of temperature in this shaft. With- 

 out detaining ourselves with the observations on the tempera- 

 ture of the air and the coal, we will only mention, that that of 

 the salt-water which collected in a small shaft in the vicinity, 

 and from which there was an uninterrupted disengagement of 

 bubbles of carburetted hydrogen, was 72°.59, and when the 

 disengagement of gas subsided, 72°.0 and 71°.60. The mouth 



* Philosophical Magazine, 1834, voL v. p. 446. 



