1868. | Temperature of the Earth’s Crust. 17 
Monkwearmouth Colliery, near Sunderland, at a depth of 1,590 
feet, from water issuing from a coal-seam at a depth of 1,499 feet 
below the sea-level, and which gave a resulting increase of tempera- 
ture of 1° for every 60 feet.* 
During the sinking of Rose Bridge Colliery, near Wigan, to the 
celebrated Cannel-seam, between the years 1854—61, careful observ- 
ations of the increase of temperature were made by the manager, 
Mr. Bryham, and communicated to the author; the following are 
the results :— 
At a depth of 483 feet the temperature was found to be 64°5° Fahr. 
AR 66° 
” o64 »” ” ” ” 
» 1,650 ,, ” ” 78° ” 
1,800+ > ” ” 80° % 
Taking the invariable temperture at 50°, and at a depth of 50 
feet, the resulting rate of increase is 1° Fahr. for every 58:3 feet. 
But of all the observations as yet made, perhaps the most 
elaborate are those which were undertaken by Mr. W. Fairbairn, 
F.R.S., during the smking of the Astley Pit of the Dukenfield 
Colliery in Cheshire.t These observations were carried on over 
a period of ten years (between 1848-59), and reach downwards to 
a total depth of 2,151 feet from the surface. Great care was taken 
to remove the thermometer from the disturbing influences either of 
the air in the shaft, or of water in the strata. The instrument was 
as often as possible inserted in a dry borehole in advance of the 
sinkings, and left in its bed from two hours to two days, according 
to circumstances. Fifty-two observations are recorded, and range 
from an invariable temperature of 51° Fahr. at a depth of 164 feet 
from the surface to 75°5° at the bottom of the pit, and 75:0° at 22 
yards lower in the roof of the “ Black coal,” taken seven months 
afterwards. This last observation does not in all probability give 
the original temperature of the stratum, which we may well suppose 
was somewhat lowered, owing to contact with the air. Rejecting 
for the above reason the last observation, we find that there has 
been an increase of 245° in 2,040 feet ; so that the average rate for 
the whole depth is 1° for every 83:2 feet. 
This series of observations is the most valuable of any that have 
been made in this country, both as regards the unsurpassed depth to 
which they extended, and the care that was taken to ensure accu- 
racy. On the whole (with occasional minor variations) they show a 
remarkable uniformity in the rate of increase, and induce confidence 
* Philosophical Magazine,’ vol. v. 
+ Another observation was made nine months afterwards, when it was found 
the temperature had cooled down 8°, or from 80° to 72°, owing to contact with the 
down-current of air. 
{ See-account of these observations by Mr. W. Hopkins, F-.B.S., in the ‘ Philo- 
sophical Transactions,’ vol. exlvii. 
VOL. V. C 
