respecting the Tcmperalurc of Mines. loi 



" I have before shown that by admitting the gradual in- 

 crease of temperature (according to our descent) after a certain 

 ratio, tlie temperature of this de]5th ought to be at the lowest 

 calculation 70°. How comes it then to be less by 11° and 18° 

 minus, since this place was in the full course of working ? " 



" I have also found that the temperature of a working spot 

 in Huel Abraham at the 180 fathom level, where the difference 

 of atmospheric pressure was 0*964, or nearly one inch, when 

 other circumstances, such as number of men, current, blasting 

 of rocks, 8:c. iScc, were similar, that the difference of tempera- 

 ture was only from 1^° to 2° ; it being 78° when the thermo- 

 meter was lowest, and 79i° to 80° when liiffhest." — (Ann. Phil. 

 July.) - "- 



" In making my experiments with the registering thermo- 

 meter, in order to obtain as correct results as possible, I al- 

 ways reduce the degree of the mercurial one to about the 

 freezing point, by sprinkling its bulb with ether, and by raising 

 the spirit one with my tongue, bringing the indices to corre- 

 spond before each immersion." 



" There appears to be little or no difference in the mean 

 temperature of the same spot in a deep and confined part of a 

 mine at work, in summer or winter; or at least the miners are 

 not sensible of any. Capt. W. Teague assures me, that he 

 has often met with ice in great abundance in Tin-Croft mine, 

 at the depth of 318 feet below the surface, and in such quan- 

 tities that the ladders have been impassable; deep crevices 

 in the walls have been completely filled, and icicles hanging 

 abundantly around him*. 



After next explaining, on the well known principles (in the 

 Ann. Phil, for Jan.) how the whole body of water in a relin- 

 quished mine becomes of an uniibrm temperature, and citing 

 certain observations of Mairan, Hales, Marriotte, and Van 

 Swinden, respecting the alternate heating and cooling of the 

 earth's surface in summer and winter, and the nearly equable 



temperature 



* To this statement by Mr. Moylc, we subjoin an extract relative to 

 the formation of ice in mines, from the concluding volume of the late 

 Dr. E. D. Clarke's Travels, which has lately appeared. He is describing a 

 descent into one of the great iron-mines of Persbcrg, near Onshytta, in 

 Sweden: tiie depth of the mine from the rocky surface to where the 

 buckets of ore were fdled ajjpears to have been about 75 fathoms. 



" As we descended further from the surface, large masses of ice apfieared, 

 covering the sides of the precipices. Ice is raised in the buckets with the 

 ore and rubble of the mine: it has also accumulated in such quantity in 

 Hoine of the lower chan)bers, that there are places where it is fifteen fathoms 

 thick, and no change of temperature above prevents its increase. This 

 bcems to militate against a notion now becoming |)reva!eut, that the tem- 

 perature of the air in mines increases directly as the deptli from the sur- 

 face, owing to the increasing icinperuturc of the cartli underthc sajncrircum- 



jtancc* 



