100 Summary Revieic of the late Investigatmis 



nerally warmer than tliat which flows from those of tin. May 

 not this arise from the action of oxides of iron and sulphu- 

 retted pyrites, which are more abundantly found in copper 

 tlian in tin lodes ? " 



" I need not here enumerate the many adventitious causes 

 of heat in mines ; but from the whole of my experiments I 

 cannot but conclude that the doctrine of the progressive in- 

 crease of heat in proportion to the depth, is without foundation, 

 since it has been proved that it may be as cold at the depth of 

 100 fathoms as the mean of this climate, which could not be 

 the case were the progressive theory correct." — {Corn. GeoL 

 Trans, vol. ii.) 



" On repeating my experiments on the temperature of the 

 water in Herland mine, I found the heat at all depths, as be- 

 fore stated (see the table), viz. 54f° in the old engine-shaft, and 

 56° in another about 60 fathoms distant ; and in a third, not be- 

 fore tried, the water was only 52°. I was given to understand 

 by Capt. S. Grose, who accompanied me, that all these shafts 

 extended to nearly the same depth. This circumstance I con- 

 ceive rather remarkable, and clearly proves the operation of 

 different causes of temperature in a very circumscribed portion 

 of ground." — {Aim. Phil. Jan.) 



" Many of the experiments" in Huel Abraham, Crenver, and 

 Oatfield copper mines, " were a few days since [in last May] 

 repeated in precisely the same spot, and under similar circum- 

 stances as before, and nearly with the same results, excepting 

 the temperature of the water accumulated at the bottom of Oat- 

 field engine-shaft below the depth of 182 fathoms from the 

 surface, in consequence of the pumps being drawn up from 

 below that level." 



" The coldest part of this water ten months ago, at the 

 depth of 1,164' feet from the surface, and in 12 fathoms of 

 water, was 66°. Last week, at precisely the same depth, it 

 was only 59° ; while the water at the surface of this shaft was 

 77°. This increase of temperature at the surface is to be at- 

 tributed to the immense quantity of warm water sent from 

 distant parts of the other mines to this shaft to be drawn out, 

 and although it falls several feet into this shaft, which keeps 

 the water in a constant and great agitation, yet it does not 

 affect the temperature at the above-mentioned depth so much 

 as might be expected." 



" 1 regret much that the registering thermometer could 

 not be sunk to a much greater depth, and quite out of the in- 

 fluence of the filling waters, as I am inclined to think that it 

 must ere this have arrived, or nearly so, to the mean annual 

 temperature, or 53°." 



" I have 



