442 Mr. Fox on the Temperature of Mines. [Dec. 
fathoms from the surface, 30 fathoms in depth, and 60° of tem- 
perature. There are no pumps in this mine, but the water has 
recently been considerably reduced, in consequence of the 
reworking and draining of some neighbouring mines; all the 
water from the higher levels, &c. must, therefore, be mixed with 
that in the mine, and reduce its temperature, which is in a con- 
siderable degree prevented in mines, which are furnished with 
pumps, by placing cisterns to receive the water at different 
Tevels. 
_ Mines which contain much water, if the workings have been 
only recently renewed, are generally of an inferior temperature to 
those of equal depth which are drained to the bottom. 
This remark applies, in a much greater degree, to mines 
which have been long stopped, and filled with water; in confirm- 
ation of which, the three following instances may be given. 
The water in Herland copper mine, in the parish of Gwinear, 
in the shaft, at the adit level, 31 fathoms deep, is only 54°, 
though the mine is 161 fathoms in depth. 
~ At South Huel Ann, in the same parish, the water in the shaft 
owas likewise 54°, the depth of the adit being 11, and that of the 
mine 23 fathoms. 
' At Gunnis Lake copper mine, in the parish of Calstock, 
which 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 indi- 
rectly, by displacing the water in the shafts, or in the upper 
Jevels that communicate with them, and which must be, in a 
greater or less degree, more accessible, and offer an easier out- 
let to the water than those which are deeper and more remote. 
If this be admitted, it follows that the water which issues out 
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 contain is nearly stationary, and as it does 
‘not readily communicate heat in a lateral direction, that its 
temperature may materially vary from that in the shafts ; whereas 
it is well known that in a perpendicular or oblique column of 
water, an interchange 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. _ 
_ Lattribute 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 commenc- 
ing 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 Cam- 
born parish, was recently resumed, after it had been for several 
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