1823.] Mr. Moyle on the Temperature of Mines. 37 



Relistian mine in Gwinear (visited on the same day) is 

 reported to have been, when at work, much hotter than mines in 

 general ; but I found the water in the adit, 25 fathoms deep, 

 onlv qo° : and at 10, 20, and 25 fathoms below the adit, it was 

 still the same. 



Huel Ann an old tin mine, 353 feet above the level of the sea, 

 is situated in granite, and is on the same lode as Huel Trumpet, in 

 the parish of Wendron. This mine has not been wrought for the 

 last 20 years, but is to be immediately reworked ; and men have 

 consequently been employed to open that part of the mine above 

 the adit. On uncovering a shaft, I found that I could drop 120 

 fathoms perpendicular. This I did with half a hundred weight, 

 to which was affixed a common bottle properly corked, sealed 

 and secured, so that with a small cord affixed, the cork was 

 withdrawn after a lapse of a few minutes. The water thus 

 drawn from the bottom was of the temperature of 52°, and a 

 pint of it left only a residuum of ]£ gr. I then sunk a day and 

 night thermometer properly secured, as in my former experi- 

 ments, and found the temperature at the depth of 30, 60, 120, 

 240, and at 720 feet, or the bottom of the mine, uniformly of the 

 temperature of 52°. The adit is 14 fathoms, thus making the 

 depth from the surface 804 feet ; and the thermometer was 

 allowed to remain at the bottom of the water for four hours. 



On repeating; mv experiments on the temperature of the 

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

 before stated, viz. 54° in the old engine shaft, and 56° in an- 

 other about 60 fathoms distant ; and in a third, not before tried, 

 the water was only 52°. 1 was given to understand by Capt. S. 

 Grose, who accompanied me, that all these shafts extended to 

 nearly the same depth. This circumstance I conceive rather 

 remarkable, and clearly proves the operation of different causes 

 of temperature in a very circumscribed portion of ground. 



At Huel Franchise, a tin and copper lode in the parish of Wen- 

 dron, 313 feet above the level of the sea, and parallel with Huel 

 Trumpet. The water in this mine, which has ceased working 

 for about two vears, was in November last at the bottom, or 180 

 feet in depth, 51°. 



Huel Nancy is on the snme lode, but half a mile east of the 

 latter mine. This mine is about 200 feet deep, and indicated at 

 all depths 51° ; while the temperature in the shade at the surface 

 was 55°. This mine has stopped more than 20 years. 



In making my experiments with the registering thermometer, 

 in order to obtain as correct results as possible, I always reduce 

 the degree of the mercurial one to about the freezing point, by 

 ■prinkfing its bulk with ether, and by raising the spirit one with 

 my tongue, bringing the indices to correspond before each 

 immersion. 



There appears to be little or no difference in the mean temptr- 



