= 
ON THE RATE OF INCREASE OF UNDERGROUND TEMPERATURE. 95 
the lower part of the bore prevents any downward convection of colder 
water from above. 
The boring has since been carried to the depth of 1,447 feet, with a 
diameter reduced to 7} inches, and Mr. Homersham made preparations 
for a final observation at the bottom with a plug consisting of a thick 
india-rubber disc covered with cement and sand ; but the vestry declined 
to incur the responsibility of having the rods lowered again for this 
purpose; and as some pieces of broken lining-tube had fallen in, there 
would have been serious risk of jamming. Mr. Homersham accordingly 
contented himself with lowering the thermometer to the bottom without 
plugging. It remained down for six days (February 3 to 9, 1885), and 
gave a reading of 763° F. The water overflowing at the surface had a 
temperature of 59° F. 
To deduce the mean rate of increase downwards, we shall assume a 
surface temperature of 50°. This gives for the first 1,337 feet an increase 
of 254°, which is at the rate of 1° F. in 52-4 feet, and for the whole 
1,447 feet an increase of 262°, which is at the rate of 1° F. in 54:1 feet. 
These results agree well with the Kentish Town well, where Mr. Symons 
found in 1,100 feet an average increase of 1° in 55 feet. 
Mr. Homersham carried on a lengthened correspondence with the 
secretary as to the best manner of taking the observations, and the 
method devised by him as above described will furnish a useful model for 
future observers. 
Thanks are also due to the Richmond Vestry for permission to 
observe, and to the contractors, Messrs. Docwra, for the loan of their 
apparatus. 
Mr. Galloway (member of the Committee) has furnished observations 
taken during the sinking of a shaft to the depth of 1,272 feet in or near 
the Aberdare valley, Glamorganshire. The name of the place is Cwm- 
pennar, and the position of the shaft is on the slope on the east side 
of the valley, near the summit of the hill which separates it from the 
oo valley. The mouth of the shaft is about 800 feet above sea 
vel. 
Observations were taken at four different depths, 546 feet, 780 feet, 
1,020 feet, and 1,272 feet, the thermometer being in each case inserted, 
and left for twenty-four hours, in a hole bored to the depth of 30 inches, 
at a distance not exceeding 2} yards from the bottom of the shaft for the 
time being. About eight hours elapsed between the completion of the 
hole and the insertion of the thermometer. The strata consist mainly 
of shales and sandstone, with a dip of 1 in 12, and the flow of water into 
the shaft was about 250 gallons per hour. 
The first of the four observations was taken in the fireclay under the 
Abergorkie vein; the second in strong ‘ clift’ (a local name for arena 
ceous shale) in disturbed ground; the third in bastard fireclay under a 
small rider of coal previously unknown; the fourth in ‘clift’ ground two 
yards above the red coal vein, which overlies the 9-foot seam at a height 
of from 9 to 12 yards. The observations were taken by the manager, 
Mr. John Beith, and are as follow: 
Depth in ft. Temp. Fahr, 
546 =~ 56° 
. 780 594° 
1,020 63° 
1,272 664° 
