40 Summary lieview of the hite Investigations 



in which it is situated, it is certainly much inferior to the tem- 

 perature "fenerally observed in mines of the same depth." 



" The undermentioned mines being partly filled with water, 

 I give the temperature of the water remaining in each." 



" North Huel Virgin, a copper mine in St. Agnes parish. 

 The temperature of the water, which stood at 39 fathoms un- 

 der the surface, was 60°." 



" Nangiles, a copper mine in the parish of Kea. The tem- 

 perature of the water, at 59 fathoms under the surface, was 

 58°. Nangiles is 88 fathoms deep at the engine-shaft. The 

 machinery for pumping the water out of this mine had very 

 recently been set to work, and had consequently made but 

 little progress in draining it. I mention this, in connexion 

 with my remarks on the temperature of stopped mines, in or- 

 der to account for its not being greater. The veins in this 

 mine are large, and remarkable tor the quantity of iron pyrites 

 they contain." 



" Tresavean, a copper mine in Gwennap. The tempera- 

 ture of the water, standing at 100 fathoms under the surface, 

 is 60°; and the whole depth of the mine is 170 fathoms. It 

 is situated on elevated ground, about 480 feet above the level 

 of the sea, and is moreover in granite, in which the tempera- 

 ture generally appears to be inferior to what is observed in 

 ' killas,' or clay slate, at equal depths." 



" Huel Maid copper mine. The water which it contains 

 is 126 fathoms from the surface, 30 fathoms in depth, and 60° 

 of temperature. 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 

 raised with that in the mine, and reduce its temperature; 

 which is in a considerable degree prevented in mines which 

 are furnished with pumps, by placing cisterns to receive the 

 water at different levels." 



" Mines which contain much water, if the workings have 

 been only recently renewed, are generally of an inferior tem- 

 perature to those of e(]ual depth, which are drained to the bot- 

 tom. This remark applies, in a much greater degree, to mines 

 which have been long stopped and filled with water ; in con- 

 firmation 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 5t°, though the mine is 161 fathoms in depth." 



" At South Huel Ann, in the same parish, the water in the 

 shaft was likewise 54° ; the depth of the adit being 11, and 

 that of the mine 23 fathoms." 



"At 



