i6 
UNDERGROUND TEMPERATURE. 
observations were made by sinking a thermometer in the earthy and 
it was found that the influence of external heat did not extend below 
25 feet. Prof Everitt in some of his calculations^ assumes that the 
surface of the earth has a temperature of 1° f. higher than that of 
the atmosphere. D^Aubuisson has put the depths not affected by 
solar heatj at between 46 and 61 ft.^ and Kupuff at 77. 
For my own observations^ I preferred to take the mean annual 
temperature (487 f.) of the atmosphere as given by Dr. Burder^ of 
Clifton, the results of 16 years’ observations. They were taken in 
latitude 5i°’27' 49 ''' n. Longtitude, 2° 36' 30", and 192ft. above 
the sea level. The point on the surface, which is about the centre 
of the Kingswood workings, is just 3J miles distant in a straight 
line. 
Adopting then 48*7 as the surface of datum, the following will 
be the tabulated result of my observations, arranged in order of 
depth, and carried out after the method above described ^ 
Depth Temperature, 
in feet. Fathrenheit. 
402 
1232 
1367 
1439 
1769 
48 7 
547 
667 
68‘S 
747 
Comparing each depth with the next, we have the following 
results : — 
First, 402 feet - - 1° for 67 feet. 
Next, 830 „ - - - 1° „ 69 ,, 
Next, 135 „ . - 1° „ 75 ,, 
Next, 72 ,, - - - 1° » 75 II 
Next, 330 ,, - - 1° 66 „ 
The average, from the surface down to depth 1769 feet, is i°f. 
^ For details'’of the observations see report of the Underground Temperatures 
Committee . — Report of the British Association, 1879. 
