236 Mr Hen wood an t/ie temperature of Mines. 



results nearly coincided with those of the observations made in 

 Cornwall. In 1822, Mr M.P. Moyle read to the Cornwall Geo- 

 logical Society a paper on the same subject, strongly opposing 

 the idea of a high internal temperature, * having previously 

 done so in the Annals of Philosophy. The other papers which 

 have appeared on this subject are by Dr John Davy -f*, Mr 

 Fox J, Mr Moyle §, and Dr Barham||. It appears from Mr 

 Fox's observations, that the mean temperature of the mining 

 district in the vicinity of Falmouth is 49.86. ^f " The wa- 

 ter pumped from the Gwennap Mines is conveyed through 

 different branch adits into a large adit or tunnel," the tempe- 

 rature of the stream passing through which, near the point of 

 its discharge into the Carnon Vale, is 69°.25, the quantity 

 being computed at 60,000 tons per day. In one of the branches 

 in which the water is conveyed from the United, the consoli- 

 dated and other mines, of which the average depth may be 

 estimated at 150 or 160 fathoms, the temperature of the water 

 is 73°.5. G^°5 is the temperature of the water in a second 

 branch, which leads from Poldice, Huel Unity, Huel Gorland, 

 and other excavations, estimated at a mean depth of 1 10 or 120 

 fathoms ; whilst a third division, proceeding from Treskerby, 

 Huel Chance, and other mines, of about an average depth of 

 100 or 110 fathoms, contains water at 65!^. Dr Forbes states, 

 that when the depth of Huel Neptune Mine was 90 fathoms, 

 the temperature of the water discharged at the pump head was 

 60° ; an increase of 36 fathoms subsequently obtaining in the 

 depth, an elevation of the temperature of the water to 62° was 

 the consequence; and that an increase of 17 fathoms in the depth 

 of Botallack Mine augmented the temperature of the water 5°. 

 Mr Fox informs us, that an accident to the machinery at Ting 

 Tang Mine occasioned an accumulation of water at the bot- 

 tom, which was then 117 fathoms in depth. When within ten 

 fathoms of the bottom, the temperature of the liquid was 63°. 5, 

 whilst that drawn from the bottom was at Qo^. The following 



• Cornwall G. Trans, ii. 404; Annals, xxii. and Phil. Mag. Ixii. 94. 



•j" This Journal, vol. iii. 75. 



X Annals, xix. 381, Cornwall G. Trans, iii. 313. and Phil. Mag, Ixii. 58. 



§ Annals, xix. 308 — 415; xxi. 35. xxiv. 446, xxvi. 259. 



II Cornwall G. Trans, iii. 150. 



IT This Journal, vol. x. p. 118. 



