448 Mr. Moyle on the Temperature of Mines. [Dec. 



summer, and to which I referred in my last communication.* 

 1 there stated the temperature of Oatfield engine shaft 182 

 fathoms from the surface, to have been whilst at work 77°, and 

 in a few months after that period, when this part had ceased 

 working, and all below was full with water, to be only 66°, and 

 the water at 12 fathoms in depth 67°. This mine has now been 

 relinquished for many months, and on sinking a registering 

 thermometer, properly secured, as in my former experiments, 

 to precisely the same depth, the temperature was found to be 

 only 54°, and this degree of heat was uniform throughout the 

 water. Thus adding to the number before given of the confor- 

 mity of temperature throughout relinquished mines, and evinc- 

 ing upon the grounds before stated^ that did the earth in reality 

 possess a natural and a greater heat, the temperature of 54° could 

 not exist. 



I also stated the temperature of the water in the then relin- 

 quished mines of Herland and Huel Alfred, the former 54°, and 

 the latter 56°. The reworking of these mines has since taken place, 

 and the following are the experiments made on the occasion. 

 The water in Herland engine shaft, being drained 20 fathoms 

 below the adit, making 52 fathoms from the surface, was found 

 to be 58°, while at 8 or 10 fathoms below the surface of the 

 water, it was still 54°. The mud in a gallery at this level was 

 also 54°, while the air was, as in the shaft, 58°. Experiments 

 of this nature were tried as opportunities occurred in the drain- 

 ing of this mine. Few of the galleries could immediately be 

 penetrated to any considerable distance on being first exposed, 

 in consequence of being choked from various causes ; but in no 

 one instance was the mud found to exceed 56° of temperature, 

 where immediate access could be had, and previously to the 

 approach of workmen ; while the air of the galleries generally 

 approached to within 1° of that in the engine shaft. The surface 

 of the water in the shaft gradually increased in temperature as 

 it descended, so that after having drained 100 fathoms of water, 

 it was found to be 66°, while at 10 fathoms in depth it still 

 retained its former standard of 54°. Experiments of precisely a 

 similar description were carried on at Huel Alfred from its 

 recommencement. They had in September last accomplished 

 the draining of more than 100 fathoms in depth, and no oppor- 

 tunity was lost in proving, by every possible method, the accu- 

 racy of the experiments, because they appeared to differ in some 

 respects from those of Herland. 



Huel Alfred was formerly found to be at all depths 56°, two 

 degrees above the water in the old engine shaft at Herland, but 

 on an equality with another. 



• Annals, vol. v. p. 31, N. S. + Ibid. 



