ON UNDERGROUND TEMPERATURE. 



133 



The temperature 75° at tlie depth of 644 feet, a temperature lower than 

 either of the two between which it stands, was taken on the first day of Mr. 

 Atkinson's observations, and was confirmed by repeated trials at that time. 

 This was the lowest depth that could then be reached, the remainder of the 

 boring being apparently plugged up with " sludge." A spike was subse- 

 qtiently attached to the thermometer case, which enabled it to pierce deeper 

 into the sludge ; but the lowest deptli which could be reached (670 feet) 

 is still far from the bottom of the bore. 



It is intended to take a fresh series of observations at every 50th foot of 

 depth, and especially to reexamine the temperatures at about 650 feet, 

 where the reversal of temperature was observed. 



The following are the rates of increase deduced from Mr. Atkinson's 

 observations, omitting the temperature 75° at the depth of 644 feet : — ■ 



The average increase between the depths of 100 and 670 feet is 1° in 

 51*2 feet. These depths are reckoned from the top of the bore-hole, which 

 is 1066 feet below the surface of the ground. Mr. Lebour assumes that the 

 temperature at the depth of 60 feet from the surface of the ground is 

 48°. Accepting tliis estimate, we have a difference of 29|-° in 1676 feet 

 (1066 + 670-60 = 1676), which is at the rate of 1° in 57-5 feet. 



Mr. David Eurns, F.G.S., reports that, from changes in the management 

 of the mines and other causes, it has not been possible as j^et to carry out 

 the dry observations at Allenheads mentioned in last year's Eenort. 



Only one other shaft has been met with at all suitable for observation,. 



