respecting the Temperature of Mines. iil 



they vary as the wind does, so that those shafts which some- 

 times have a current downwards, on a change of the wind 

 have an upward cm-rent, and vice versa. Tlie same thing 

 takes place with regard to the levels under ground ; changes of 

 wind making the current of air run in opposite directions at 

 different times. The strength also of the currents under 

 ground, depends upon the wind at the surface; when it blows 

 hard, the current is strong under ground, and vice versa. 



' We find no want of air under ground, even in the deepest 

 parts, where a communication is made from one level to an- 

 other by means of a shaft or a 'ixins, or from one shaft to an- 

 other by a level. The current of air is frequently so strong 

 even towards the bottom of the mine as sometimes to blow 

 out a candle ; in fact, we never find a deficiency of air miless 

 it be in a level extended a considerable way from a shaft with- 

 out having a communication with any other part ; or in a shaft 

 sunk far below a level : in which cases we are frequently un- 

 der the necessity of having recourse to some artificial means 

 to procure air in the part wanting it.' 



' I ascertained the currents of the shafts at the surface by 

 throwing feathers, pieces of paper, and straw, into them. In 

 many cases the currents were so strong as to cany these things 

 vajiidly upwards to the height of several yards.' 



" Though these currents in the shafts and more open gal- 

 leries are considerable, it is still true that in the great majority 

 of the galleries no current, or one that is very slight, is per- 

 cejnible ; and that in all such galleries as communicate by one 

 extremity only with a shaft, or with other levels by a 'lains, at 

 some distance from their inner extremity (both of which kinds 

 constitute the greater number of the working galleries), there 

 is no current whatever, and in fact, no possibility of there be- 

 mo one. Many of these galleries are several hundred feet in 

 length, with no other outlet but their extremity at the shaft. 

 A siifficient proof of the general stillness of the air in mines is 

 afforded by the fact of lanterns being unknown in them ; and 

 during all my visits to these gloomy regions I never saw the 

 candle extinguished by a current of air, more than once or 

 twice." 



These introductory remarks are succeeded by the registers 

 of observations made in six mines, the mean results of which 

 Dr. Fr.rbes afterwards presents in the subjoined table, to which 

 we liave prefixed a tabular view of various particulars respect- 

 ing the ccconoiny and circumstances of those mines, drawn up 

 from the statements in his registers. 



Vol. <A. Xo. ;i02. JKue 1823. 3 K Circum- 



