respecting tlie Temperature of Mines. 41 



" At Gunnis Lake copper mine, in the parish of Calstock, 

 whicli is 125 fathoms deep, the water in the shaft, at the adit- 

 level 35 fathoms deep, was 57°." 



" The water that flows out through the adits of stopped 

 mines, is, I presume, derived from the superincumbent 

 strata, or indirectly, by displacing the water in the shafts, 

 or in the upper levels that communicate with them, and 

 which must be in a gi-eater or less degree more accessible, 

 and offer an easier outlet to the water, than those which are 

 deeper and more remote. If this be admitted, it follows that 

 the water v.hich issues cut of the tops of shafts of stopped 

 mines, does not proceed from the deeper levels ; but, on the 

 contrary, it seems highly probable that the water they con- 

 tain is nearly stationary, and, as it does not readily communi- 

 cate heat in a lateral direction, that its tiemperature may ma- 

 terially vary from that in the shafts ; whereas it is well known 

 that in a perpendicular or oblique column of water, an inter- 

 change will take place between the warmer part of the liquid 

 column at the bottom and the colder at the top, till an equality 

 of temperature is produced through the whole." 



" r attribute the higher temperature of the water in Gunnis 

 Lake shaft, at least in part, to the very elevated ground in its 

 immediate neighbourhood ; although the relative temperature 

 of the water in the shafts of stopped mines may also depend 

 on the greater or less depth at which the columns of water 

 commencing above the adit-level communicate with the shafts, 

 or with the levels connected with them." 



" When the working of Tincroft tin and copper mine, in 

 Camborn paiish, was recently resumed, after it had been for 

 several months suspended, an opportunity occurred for ascer- 

 taining the temperature of the water, when it v. as suiik to the 

 tiepth of 126 fathoms under the surface, and was onli/ 10 fa- 

 thoms deep, in the bottom of the mine. It was then found to 

 be 63° ; and this was before many men had resumed their la- 

 bours, or indeed any of them, at the inferior levels ; and more- 

 over, at the time of making the observations, even the few men 

 who worked in the mine had not been in it for the space of 

 nearly two days. Near the middle of 1S19, when the water 

 stood at the same place in the mine, and it was, and had long- 

 been, in a state of full working, the temperature of the water 

 at the bottom was only 59°. Perhaps the water will again 

 be reduced to this temperature, if it should remain at the same 

 depth in the mine ; for is it not reasonable to suppose, that 

 the droppings of colder water down through the shafts, must 

 aflf'ect the temperature of that at tlie bottom ? " 



" In conseciuence of an accident in the steam-engine at 

 \'ol. C2. No. 303, Jnly 1823. F Ting- 



