389 



IX. — Note on the Underground Temperature at Dolcoath Mine, May 

 1st, 1877.— By J. H. Collins, P.a.S. 



ON the 1st of May, 1877, I found myself at the bottom of 

 Dolcoath Mine, which is now 370fath. deep. I had with me 

 a good thermometer and observed the following temperatures. — 

 Water coming from the footwall in the 248 fath. level 



near the bottom of the man-engine . . . . 68 ^F 

 ,, Western feeder into the sump below the 3? 8 



fath. level, 370 faths. from surface . . . . 87'8 

 ,, Small stream coming from the hanging wall in 



the bottom level 90-5 



AiE. in great stopes above the 326 fath. level, 358 faths. 



from surface 75" 



This I regard as the normal temperature of the mine, as the 

 open space is so large that the temperature cannot be much 

 affected by the candles and the breathing of the men. 

 Am, 314 fath. level going west from engine shaft . . 77* 

 ,, from exhaust port of boring machine in the west- 

 ern end of the same level 71-5 



Considering the great depth of the mine and the high temper- 

 ature of the water coming into the fissure from the surrounding 

 " country^" I think these temperatures speak well for the 

 general ventilation of the mine. The observations in the 314 

 fath. level also demonstrate the great value of a boring machine 

 worked by compressed air as an aid to ventilation, since it sup- 

 plies a constant stream of pure water exactly where it is most 

 wanted, viz: — in the end where the men are at work, and this 

 air is several degrees cooler than that of the level into which it 

 is discharged. 



On the occasion of my visit, twelve men were in the end with 

 the machine for about f of an hour, most of us with lighted 

 candles, and although the temperature rose to 94°, no incon- 

 venience ■n^as felt from the vitiation of the air. 



