respecting Ihe Temperature of Mines. 445 



24 gallons, 2° ; 16 gallons, 3°; 12 gallons, 4°; and so on.— 

 To this we may add l-20th of the whole, for the effect of heat 

 generated at the surface of the body." 



" To these direct sources of heat in mines I have now to 

 add another, which, although quite unconnected with the ope- 

 rations of the miner, results from them. This is a cause which 

 must be of universal oj^eration, yet has not hitherto, as far as 

 I know, been suspected to be at all concerned in the tempera- 

 ture of mines. What I allude to is the lessened capacity for 

 caloric, of the air in mines, in consequence of its increased 

 density. It has been long known that the temperature of the 

 atmosphere decreases as we ascend in it ; and it has been as- 

 certained that the rate of decrease is about one degree of 



Fahrenheit for every 300 feet The converse of course is 



true but in estimating the heating power of this source it 



will not perhaps be right to allow one degree of increase for 

 every 300 feet, in mines generally, as this is the maximum that 

 can happen in any case ; and as there are so many situations in 

 which there is hardly any current, and where, consequently, 

 the increase must be much less, perhaps it may be sufficient 

 to allow 1 ° of increase over the whole of a mine, for a descent 

 of 600 feet." 



" Let us now apply the results of these calculations to a sin- 

 gle mine ; and, in the first place, let us confine our altention 

 to the temperature of the water, as both the actual quantity 

 and lieat of this are much more readily estimated than those 

 of the air. I take Huel Vor as an example." 



" The monthly expenditure of candles in this mine, as has 

 been already mentioned, is 3000 lbs., that of gunjiowder 

 3500 lbs. — the number of men employed under ground 548, 

 of which 180 are constantly there." 



" Supposing then that the whole of the extraneous and 

 artificial caloric, extricated in mines, goes to the elevation of 

 the temperature of the water (and this is allowing, of course, 

 a vast deal more than the truth), the following will be the 

 quantity of water, according to the foregoing calculations, 

 raised every month in Huel \'or from the mean temperature 

 of 52= to 67°, or 15° :" Gallons. 



SOOOlbs. of candles (125 galls, per lb.) ... 375,000 

 3500 lbs. of gunpowder (63 galls, per lb.) 220,500 



Friction and percussion 27,340 



Bodies of 180 men ._ 1 8,140 



Total per month 640,980 

 " This is little more than one-eightieth part of tlie water 

 actually discharged at the adil, of the leuiperalure of 67°." 

 " In the aljove calculations I have made no allowance for 



the 



