OF ORES AND COALS. 



ing in the mine ; and to guard againft both kinds, a free cur- 

 rency of air is circulated through all the works, entering one, 

 and coming up another. 



Two expedients have been tried by the late ingenious Mr. 

 lljle Spedding, of Whitehaven, for the fafcty of the workmen in 

 coal mines, infeftcd with the fulminating vapour ; one is by 

 framing the perpendicular fhafts or pits with timber where $t 

 is fufpected to be, and to place a tube of about two inches fquare 

 in a fmall hollow behind it, elevated four yards above the Oftinm 

 of the mine, to collect the damp air to one fide of it r and to con- 

 vey it out of its precincts ; the other is by the ufe of fteel and 

 flints fixed ia. a fmall engine with a wheel, which give a glim- 

 mering light to the miners ; this fort of vapour not firing by 

 fparks, though it does by flame. When it comes out of the top 

 of the tube it is cold as froily air, yet after it has been imprifoned 

 and confined in a bladder even for near a month, it will take fire 

 at a lighted taper or candle, if gently prelTed into it through 

 the orifice of a pipe, and when the candle is withdrawn, will 

 continue burning till it is all fpent. 



In the grounds at JBenwell, about a quarter of a mile north 

 from the river Tyne , a coal-mine took fire at a workman's candle, 

 negligently placed, and continued burning about 3.0 years, 

 though at firft fo fmall, that a propofal was made to put it out 

 for fo low a reward as, 2 s. 6d. but it was not accepted. It after- 

 wards acquired fuch force and ftrength from the kindled ful- 

 phurs and bitumens, that it raged with fury, in various direc- 

 tions and depths ; fometimes taking its courfe eaft and weft, and 

 at laft to the north, into the grounds of Fenham, near a mile from 

 its firft appearance, committing great ravages in its way, only 

 confpicuous by its flames and columns of fmoak in the night. 



S 2 The 



