188 



REPORT 1869, 



Slimed to represent pretty accurately the temperature of the soil at the same 

 depth, was 62°*4 in Duncrue shaft at the depth of 570 feet (observed No- 

 vember 7, 18G8), and 66° in Mr. Dalway's new shaft at the depth of 770 

 feet (observed November 14, 1868). Assuming 48° as the mean surface- 

 temperature, the increase of temperature downwards would be at the rates 

 of 1° in 40 feet and 1° in 43 feet respectively. The soil in both cases was 

 yellow clay. 



Mr. David Burns, of H.M. Geological Survey, now stationed at Allendale 

 near Carlisle, has taken observations in that neighbourhood, which he thus 

 describes : — " The first shaft I tried is over 50 fathoms in depth, and is 

 about half full of water. It is situated on the summit of a ridge a few 

 yards distant from a fault of some 900 feet throw. The flow, or rather 

 change, of water in it, from these or other causes, is considerable, as is 

 shown by the temperature. The result of my observations may be put 

 thus : — 



" After a period of drought — 



feet. o 



" Depth 160 Temperature 47-5 



„ 200 „ 47 



„ 250 „ 47-7 



„ 300 „ 47-7 



" The minimum temperature is at 200 feet. This reading may be relied on, 

 as I repeated the observation to make sure of it. Perhaps at this level lies 

 the chief feeder of water. 



" Shortly after heavy rains — 



feet. ^ 



" Depth 160 Temperature 47 

 „ 200 „ 47-5 



„ 250 „ 47-3 



„ 300 „ 47-3" 



Mr. Burns goes on to relate his unsuccessful attempts to take observations 

 in two other shafts, which turned out to be closed, probably by platforms, at 

 a depth of several feet below the surface of the water. 



In concluding this Eeport, I would beg to direct attention to a valuable 

 summary of observations of underground temperature at great depths con- 

 tributed by Mr. Hull to the ' Quarterly Journal of Science' for January 

 1868, from which the following Table of results has been condensed : — ■ 



Depth, Temperature at Average rate 

 in bottom, in of 



feet. degrees Fabr. increase, 

 o feet. 



Puits de Grenelle, near Paris 1794-6 81-95 1 for 59 



Boring at Neu Salzwerk, Westphalia . 2281 91-04 1 „ 54-68 



Boring near Geneva .... .... 1 „ 55 



Boring at Mendorff, Luxemburg .... 2394 .... 1 „ 57 



Monkwearmouth Colliery 1499 .... 1 „ 60 



Eose Bridge Colliery, near Wigan . . 1800 80 1 „ 58-3 



Astley Pit, Dukcnfield, Cheshire 2040 75-5 1 „ 83-2 



Mr. Hull strongly insists on the necessity of observations at greater 

 depths. He gives reasons for maintaining that, at depths exceeding 2000 



