ON THE RATE OF INCREASE OF UNDERGROUND TEMPERATURE. 181 



rapidly driven in the solid coal. The hole was bored in the very face, to 

 the depth of four feet. The thermometer (one of the Committee's slow- 

 action non-registering instruments) was placed at the inner end ; then a 

 wooden cylinder of nearly the same diameter as the bore-hole, and 9 inches 

 long, was pushed in until it came in contact with the copper case of the 

 thermometer ; and lastly a wooden plug, wrapped round with cloth, was 

 driven firmly into the mouth of the hole. The thermometer was at 58° F. 

 when it was put into the hole, and after remaining there from 2 p.m. on 

 August 25th, 1876, to 3.45 p.m. on the following day, it stood at 62°7. 

 There was no water whatever in the hole, and the depth below the surface 

 of the ground was 855 feet. 



The circumstances of this observation seem to preclude any consider- 

 able disturbance of the normal temperature ; and combining it with the 

 mean annual temperature at the surface, which is said to be 51 0, 5, we 

 have an increase of ll°-2 F. in 855 feet ; which is at the rate of 1° F. for 

 76 feet. 



Two other observations were taken in other parts of the mine. They 

 are not directly available for the purposes of the Committee, but were 

 intended to test the influence of air-currents on the temperature of the 

 coal ; and they show variations of 2° or 3° according to the season of 

 the year. 



Observations are being taken for the Committee by Mr. G. F. Deacon, 

 Borough Engineer of Liverpool, in a bore which has attained the depth 

 of 1004 feet, in connexion with the Liverpool Waterworks at Bootle. 



The temperature at this depth is 58°1. The observation nearest the 

 surface was at the depth of 226 feet, the temperature at this depth 

 being 52°. We have here a difference of 6°'l in 778 feet, which is at the 

 rate of 1° for 128 feet, and the same rate is approximately maintained 

 throughout the descent. For instance, at 750 feet the temperature was 

 56°, which gives 1° for 131 feet by comparison with the depth of 226 feet, 

 and 1° for 121 feet by comparison with the bottom. 



The bore is 24 inches in diameter, and the observations were taken 

 with a protected Phillips's maximum thermometer every Monday morning. 

 The operation of boring was continued up to twelve o'clock on Saturday 

 night, and was not resumed till the temperature had been taken on the 

 following Monday. The time that the thermometer remained at the 

 bottom was not less than a quarter of an hour, and was sometimes half 

 an hour. 



The rock-formation consists of the pebble beds of the Bunter or lower 

 trias, and most of it is described as hard, close-grained, and compact. 

 The speed of boring is indicated by the dates of the observations at 

 226 and 1004 feet, the former being Nov. 12th, 1877, and the latter 

 Aug. 12th, 1878. A month was lost by the jamming of the drilling 

 tool, in May and June, 1878, when a depth of about 890 feet had been 

 attained. 



The depth from the surface of the ground to the surface of water in 

 the bore has gradually decreased from 66 feet, when the bore was at 318 

 feet, to 52 feet when the bore was at 800 feet, and to 51-1 feet at the 

 present depth. It would thus appear that the inflow of water from below 

 has increased with the depth attained. There is a slow percolation 

 from the upper part of the water-column to an underground reservoir 

 near at hand, the top of the water-column being considerably higher than 

 the top of the water in the reservoir. Mr. Deacon remarks that the 



