208 Observations on Underground Temperature. [April, 



A question of speculative interest was determined in a bore 

 made at Kirkland Neuk. A coal-seam passed through had been 

 charred, owing to contact with greenstone (or trap rock) ; and the 

 question occurred, "Are there any remains of the heat which 

 charred the coal in ancient times ; or has it passed off so long ago 

 that the strata are now not sensibly warmer on account of it ? " 

 The observations seemed to establish the latter alternative, the bore 

 being colder than its neighbour — that taken at Blythswood. 



The observations taken at Kentish Town extended to a depth 

 of 1100 feet, with an ultimate temperature of 70°, giving the mean 

 rate of increase at *0191° per foot, or 1° per 52'4 feet, the mean 

 surface temperature being taken at 49°. 



In the case of the Kentish Town bore-hole, notwithstanding the 

 care taken to prevent the influence of the external air affecting the 

 temperature of the water in the well, it was found by Mr. Symons 

 that this influence extended to a depth of nearly 200 feet, — the 

 temperature of the water rising and falling with that of the season 

 of the year down to this depth. The well, however, was no less 

 than 8 feet in diameter. 



The experiments undertaken at Rose Bridge Colliery, near 

 Wigan, by the manager, Mr. Bryham, which 1 have recently com- 

 municated to the Royal Society,* deserve special notice, as having 

 been made during the sinking of the deepest coal-pit in Britain. 

 The results arrived at differ so strikingly from those obtained at 

 Dukinfield Colliery, situated near the eastern border of the same 

 coal-field of Lancashire, and only a little less deep, that a discussion 

 of the cause of this discrepancy may not be without interest. 



An account of the observations at Dukinfield Colhery, undertaken 

 by Mr. W. Fair bairn, F.R.S. (1848-59), has already been given in 

 the pages of this Journal,! and was originally communicated by 

 Mr. W. Hopkins to the Royal Society.} The depth of the shaft 

 is 2151 feet, with an ultimate temperature of 75*5° taken in the 

 seam of coal known as the " Black Mine " of that district. The 

 mean result is a rate of increase of 1° for about every 83*9 feet. 



The observations at Rose Bridge, near "Wigan (1854-61), were 

 at first extended only to the depth of 1800 feet, giving a resulting 

 temperature in the strata of 80° ; but it having been determined by 

 the proprietor to carry down the shafts to the " Arley Mine " coal, 

 which was known to be at a depth of over 600 feet below, opera- 

 tions were commenced in the spring of the year 1868, and in the 

 space of fourteen months the Arley Mine was successfully rt won." 

 The total depth reached was 2424 feet, with an ultimate tempera- 

 ture (taken in the coal itself) of 93*5°. Throughout the whole 

 series of experiments from 1650 feet downwards, the increase 



* 'Proceedings of the Eoyal Society,' vol. xviii. (No. 116), p. 173. 

 t Vol. v., p. 17. % 'Philosophical Transactions,' vol. cxlvii. 



