UNDERGROUND TEMPERATURE. 1 7 
in every 68 feet, or comparing the depth, 402 feet, with the lowest 
1° in 68*35 feet. 
All the observations made on behalf of the British Association 
Committee show an increase downwards, but the rate varies con- 
siderably, as the following tables^ will show. In their construction, 
I have extracted the chief results, taking the lowest depths as the 
most reliable. I do not wish to under-rate their value, in any way, 
but I have little faith in the majority of observations made in shafts, 
wells, or bore-holes, unless special precaution has been adopted to 
protect the thermometer against the influences before referred to. 
Indeed I question whether sufficient precaution is practicable. 
OBSERVATIONS IN MINES. 
Surface 
Temp. F. 
Greatest 
Depth. 
Temp. 
Registered. 
Feet per 
“ F„ i“. 
Baldon Colliery, between New- 
castle and Sunderland 
48° 
1514 
79° 
49 
Fowler’s Colliery, Pontypridd, 
South Wales 
5 i °-5 
846 
62^*7 
76 
Kings wood Colliery, near Bristol 
48° *7 
1769 
74°7 
68 
OBSERVATIONS 
IN SINKING SHAFTS. 
Name of Shaft. 
Surface 
Temp.F. 
Greatest 
Depth. 
Temp. 
Registered. 
Feet per 
1° F. 
Rosebridge .. 
49° 
2445 
94° 
54*3 
Dunkingfield, Cheshire 
49° 
1401 
66r 
80 
^ The result given in the Tables by no means represents the whole of the work 
done by the British Association Underground Temperature Committee. 
Vol. III. c 
