respecting the Teviperatnre of Mines. 351 



'* I had made a second table," Mr. Fox observes, " contain- 

 ing the results of several experiments on the temperature of 

 cross levels and shafts, in some of the same mines, at a distance 

 from any metaUic veins ; but as its contents are too various and 

 extensive to be comprised in a printed sheet, I will merely men- 

 tion a few of the particulars." He then gives some observations 

 on this part of the subject, made in the United Mines, Dol- 

 coath, Ting-Tang, Huel Squire, Treskerby, and Chasewater, 

 which " will suffice to show that the temperature, at a distance 

 from the metallic veins, and at the same depths, is, on an aver- 

 age, nearly three degrees below that of the veins, as given in 

 the printed table." 



" In many of the observations referred to in the tables, the 

 bulb of the thermometer was buried in the veins, or rock, to 

 the depth of at least six or eight inches, and was filled round 

 with earth, &c. so as to prevent the free admission of air." 



" It is evident that there exist many local and accidental 



causes, which operate in our mines, and affect their tempera- 

 ture. The lighted candles, and the blasting of the rocks, have 

 doubtless some influence in augmenting the heat; and the pre- 

 sence of the workmen must also have the same tendency, 

 although probably in a small degree at the bottom of deep 

 mines, where the temperature so nearly approaches to that of 

 the human body. Moreover, the warm vapour and air, which 

 always arise from die bottom of mines, must raise the tempera- 

 ture of the upper levels in a greater or less degree, according 

 to their relative situations. On the other hand, the currents 

 of air which descend through some of the shafts, or are forced 

 through the air-pipes for the supply of the miners, and likewise 

 the water which finds its way through the strata and veins, 

 from more elevated situations, doubtless tend, in a considerable 

 degree, to diminish the heat in the deeper levels." 



" How far these opposite causes may counterbalance each 

 other, it is not easy to ascertain ; but if duly considered, they 

 will greatly reconcile the want of complete accordance in the 

 results noted in the tables : and it is evident, that observations 

 made on the temperature at the bottom of mines are most to 

 be confided in, not only for the foregoing reasons, but also be- 

 cause of the proximity of this part to the unbroken ground. 

 There are some cases in which it cannot be supposed that the 

 high temperature observed, can be occasioned by any acci- 

 dental circumstance. At the bottom of Dolcoath mine, for 

 instance, there is a large stream of water issuing from one of 

 the veins at b'J" of Fiihrenheit, while the air near the same 

 place is generally one or two degrees lower : — this is only one 

 example amongst many of the same kind. The most striking 



one 



