1823.] Mr. Moi/k on the Temperature of Mines. 35 



of my communication to the same Society, and which has been 

 published in the second volume of their Transactions. The 

 substance of this communication I conceive it necessary in this 

 place to detail, as I shall have frequent occasion to refer to it. 

 I have since collected some additional facts which, I conceive, 

 will tend to strengthen very materially the opinion I originally 

 advanced. These shall follow in the second place, reserving any 

 comments for the conclusion. 



As it is only by comparing the different results of the experi- 

 ments of individuals that the truth, or an approximation to it, can 

 be elicited, I conceive too much attention cannot be paid to the 

 manner in which these experiments are conducted. With 

 respect to the temperatures now given, where there has been any 

 degree of uncertainty in the result, they have been taken twice 

 or thrice in the same spot, by different methods, such as burying 

 the thermometer in the earth, or rock of the gallery, in mud or 

 water, lodging in the gallery, in the full stream of water flowing 

 from the veins, by allowing it to remain 15 or 20 minutes during 

 each observation, and by the correspondence of two or more 

 thermometers at the same time. 



I have lately ascertained the temperature of three levels which 

 have been driven from Crenver directly under the deepest level 

 in Trenoweth (the mine alluded to in the Annals for April, p. 416). 

 At the depth of 124 fathoms below the adit level, or 936 feet 

 from the surface, it was 57° ; at 984 feet, 58° ; at 1044 feet, 58°. 

 Five months before, when the miners were at work in the last 

 mentioned level, the temperature was 68°. 



In Oatfield copper mine in May, 1822, the temperature of the 

 air in the engine shaft at the adit level was 61°. At the depth 

 of 1092 feet from the surface, it was 77°, and at 1272 feet, and 

 480 feet east of the shaft, 78° ; at 1332 feet, and 600 feet east of 

 the shaft, it was 81° ; but at the same level, 360 feet west of the 

 shafts, it was only 78° : neither of these spots were working 

 places ; but the latter was more contiguous to them than the 

 other. At the depth of 1392 feet, in a working part 72 feet east 

 of the shaft, it was 80°; and only 24 feet deeper, 180 feet west 

 of the shaft, in a confined end, it was 85°. Here the water 

 issuing in considerable streams from two small veins, at the bottom 

 of the gallery, a few feet apart, indicated the different tempera- 

 tures of 82° and 86 }/>. 



Since the temperature of the different parts of this mine has 

 been taken, the pumps have been drawn up from the deepest 

 part, and the shaft, below the depth of 182 fathoms from the 

 surface, has been for some months full of water. At this level, 

 the temperature was previously 77°, but a few months afterwards 

 (in Sept. last), when the water had risen to the level, its temper- 

 ature, a few feet below its surface, was 69° ; and at the depth of 

 72 feet in the water, it was 71°. A fortnight after this, I 

 repeated the experiment, and found the temperature, a lew feet 



d2 



