42 Mr. Moyle on the Temperature of Mines. [Jan. 



from any foreign source, the conclusion is equally in favour of 

 the natural high temperature of the body of this earth at certain 

 depth." 



VV r ill these gentlemen, I would ask, still maintain the same 

 sentiments ? If so, their theory must fall to the ground, as we 

 can now clearly prove that these very collections of water possess 

 even a less temperature than the supposed mean of the climate ; 

 e. g. Huel Ann, and the third shaft in Herland ; one 130, and the 

 other 160 fathoms in depth, Ding Dong, Huel Rose, Huel Fran- 

 chise, &c. 



The only instances of importance, Dr. F. brings in support of 

 this hypothesis, are the following : a large isolated collection of 

 water in Botallack mine is stated to be 62° at the depth of about 

 400 feet from the surface. Here it may be necessary to refer to 

 his general description, and we find it is an old working full of 

 water, 80 fathoms deep below the gallery at 400 feet, and is 

 under the sea. The surface of this water is 62°, while the air 

 was 66° ; the heat of this water at the bottom of the working is 

 not given. He continues, " a still stronger instance, perhaps, in 

 support of the 6ame conclusion, is afforded by the details of 

 the other submarine mine Little Bonnds. This mine was 

 formerly worked to the depth of 500 feet. Of late years, very 

 little has been done, and the water has risen to within 40 

 fathoms of the adit, where it is kept stationary by the partial 

 operation of the pumps. There is thus a permanent body of 

 water extending from the depth of 300 to that of 500 feet below 

 the surface, and, perhaps, to half that distance horizontally. 

 This water, as discharged by the pumps in 1822, is of the tem- 

 perature of 56tJ-°." Pray what has this to do with the tempera- 

 ture of the central part or bottom of the collection ? And yet 

 Dr. F. in nearly the following page, states, that a large body of 

 water resembling the last has accumulated in the old wrought 

 part of Ding Dong mine ; at the depth of 444 feet below the 

 surface, the workmen had just cut through the barrier which 

 divided them from this old working, and the stream of water 

 which issued forth (and which was the bottom of the large col- 

 lection), was only 52-1-°, thus at once proving what is actually the 

 case, that, as I before stated, it may be as cold at the very cen- 

 tre of the earth as at any distance beneath its surface. 



In the next place, I do not conceive that their opinion can 

 be supported, because Dr. Forbes's philosophical reasoning on 

 all the extraneous sources of caloric falls short of what is actually 

 observed, and that we must attribute this extra portion as derived 

 from the earth itself; for I should imagine that there are few 

 more difficult problems, than a true estimation of the power of 

 the infinite sources of caloric in a mine in the full course of 

 working. 



In making a few observations on the foregoing experiments, I 

 must remark in the first place, that in mines which are at work 



