192 ^ THE FIRE-DAMP'S FAMILY CIRCLE. 



aguliers. His record of these experiments, published in the 

 Philosophical Transactions, is entitled ' An experiment to 

 show that some damps in mines may be occasioned only by 

 the burning of candles under ground, without the addition of 

 any noxious vapour, even when the bottom of the pit has a 

 communication with the outward air, unless the outward air 

 be forcibly driven in at the said communication or pipe.' 



As will be seen from a perusal of the title, the experi- 

 ments of Desaguliers inculcate the laws of ventilation as now 

 well understood ; though at the time when Desaguliers per- 

 formed his experiments, the word ' ventilation' does not seem 

 to have taken its place in our vocabulary. The record of the 

 doctor's experiments is given in so few words, the experi- 

 ments are moreover so neat and demonstrative, that we will 

 transcribe the account of them as originally given. 



Exp. 1. In a cylindric glass receiver open at both ends, 

 whose lower end is plunged in water, and upper end covered 

 with a plate with a hole of near an inch bore, a candle of 

 six in the pound will not burn quite the time of one minute 

 before it goes out. 



Exp. 2. A candle will burn almost as long when the 

 receiver is quite covered. 



Exp. 3. The receiver, having the hole of the plate open, 

 and a pipe at bottom communicating with the external air, 

 will burn but a little longer than in the first experiments, 

 and if you blow in at the pipe with your mouth, it will go out 

 rather sooner. 



Exp. I. Blow in at the pipe with bellows, and the 

 candle will burn as long as you please. 



The vast development which the industrial arts of the 

 country underwent during the latter half of the last century 

 led to a proportionate increase of coal-mine working. The 

 steam-engine being now applied to pumping, coal-miners were 

 no longer limited in their descent by the presence of subter- 

 raneous waters, and coal-mines assumed dimensions in com- 



