BEPORT — 1882. 



Fifteenth Report of the Committee, consisting of Professor Everett, 

 Professor Sir William Thomson, Mr. G. J. Symons, Sir A. C. 

 Eamsay, Professor A. Geikie, Mr. J. Glaisher, Mr. Pengelly, 

 Professor Edward Hull, Dr. C. Le Neve Foster, Professor A. S. 

 Herschel, Professor G. A. Lebour, Mr. A. B. Wynne, Mr. Gallo- 

 way, Mr. Joseph Dickinson, Mr. G. F. Deacon, Mr. E. Wethered, 

 and Mr. A. Strahan, appointed for the purpose of investigating 

 the Rate of Increase of Underground Tertipjerature doivmoards 

 in various Localities of Dry Land and under Water. Dragon 

 up by Professor Everett (^Secretary). 



One portion of the duty assigned to the Committee is the investigation 

 of the rate of increase of underground temperature downwards under 

 luater. This part of their task has remained in abeyance until the past year, 

 but through the good oflSces of Professors Lebour and Merivale observa- 

 tions have now been obtained from a colliery which runs to a considerable 

 distance under the sea at Whitehaven, Cumberland. 



The observations were taken in holes bored upwards for the purpose 

 to a distance of 4 feet in the roof of the ' Main Band,' at Croft Pit, under 

 the direction of the manager, Mr. G. H. Liddell. 



The holes were well plugged with clay, and the thermometer (one of 

 the Committee's slow-action instruments) was in each case left in the 

 hole for 7 days. The distance beyond low-water mark was 430 yards in 

 the case of two of the boreholes, and 1,340 yards in the case of the other 

 two. The depths below ordnance datum were 1,140 feet for the two 

 former, and 1,250 feet for the two latter. The depth of the sea in all 

 four cases is estimated at 12 fathoms. The temperature observed was 

 exactly the same in all four holes, namely, 73° F., and, in one instance, 

 this was verified by reinserting the thermometer with its bulb upwards 

 instead of downwards. These data give 1,195 feet as the mean depth 

 below ordnance datum, and 1,123 feet as the mean depth below the bottom 

 of the sea. Assuming 48° as the mean temperature of the bottom of 

 the sea, we have, therefore, an increase of 25° F. in 1,123 feet of ground, 

 which is at the rate of 1° F. in 45 feet. 



Mr. E. Garside has furnished two more observations, one of them 

 from the same neighbourhood as his previous observations — the East 

 Manchester coal-field — and the other from South Stafibrdshire. They 

 were made with the slow-action thermometer, used in precisely the same 

 manner as before. 



The former observation was taken on May 4, 1882, in Denton Colliery, 

 Lancashire. The hole was drilled at 1,317 feet from the surface, nearly 

 vertically below the bed of the river Tame, which divides the estate of 

 Denton Colliery from that of Bredbury Colliery, and the temperature 

 observed was 66° P. Assuming a surface temperature of 49°, this gives 

 an increase of 17° in 1,317 feet, which is at the rate of 1° in 77^ feet, 

 being nearly identical with that found at Bredbury Colliery. 



The other observation was made at Lye Cross Colliery, Dudley (north 

 of Wolverhampton). The thermometer was placed, as usual, ia a hole 

 about 4 feet deep, drilled for the purpose in ground newly opened, free 

 from cracks or other visible irregularities, and also free from any strong 

 air-current. It was at the depth of 700 feet from the surface, in the hard 



