tfi/'ghling the Mines so as to prevent its 'Explosion. 451 



I trietl similar experiments, tlirowin."; in mixtures of air and 

 fire-damp, some containing- the. maximum and others the mini- 

 mum of fire-damp ne.-essarv for explosion, and always with the 

 same satisfactory results. The flame considerahly increased, 

 and was soon extinguished. 



I introduced a lighted lantern to which air was supplied by 

 two glass tubes ~ of an inch in diameter and half an inch long, 

 into a large jar containing an explosive mixture of 1 part of 

 fire-damp and 10 parts of air ; tiie taper burnt at first with a 

 feeble light, the fl'une soon became enlarged, and was then ex- 

 tir)guished. I repeated these experiments several times^ and 

 with a perfect constancy of result. 



It is evident, then, that to prevent explosions in coal mines, 

 it is only necessary to use air-tight lanterns, supplied with air 

 from tubes or canals of small diaaieter, or from apertures co- 

 vered with wire gauze placed below the flame, through which 

 explosions cannot be communicated, and having a chimney at 

 the upper part, on a similar system for carrying off the foul air; 

 and common lanterns may be easily adapted to the purpose, by 

 being made air-tig!it in the door and sides, by being furnished 

 with the chimney, and t!ie system of safety apertures below and 

 above. 



The principle being known, it is easy to adopt and multiply 

 practical applications of it. 



The first safe-lantern that I had constructed was made of 

 tin-plate, and the light emitted thvo'.igh four glass plates in the 

 sides. The air was admitted round the ijottom of the flame from 

 a number of metallic tubes of f of an inch in diameter, and an 

 inch and i lo''^* The chimney was composed of two open 

 cones, having a common base perforated with many small ajicr- 

 tures, and fastened to the top of the lantern, which was made 

 tight in a pneumatic rim containing a little oil ; the upper and 

 lower apertures in the chimney were about J- of an inch : the 

 lamp, wliich was fed with oil, gave a steady flame of al)out an 

 incli high and half an inch in diameter. When the lantern 

 was slowly moved, the lamp continued to burn, but more feebly j 

 and when it was raj)idly moved, it went out. To obviate this 

 circum stance, I surrounded the bottom of the lantern v/ith a 

 perforated rim ; and this arrangement perfectly answered the 

 end |)ropt)sed. 



I had another chimney fitted to this lantern, furnished with 

 a number of safety tin plate tubes of the sixth of an inch in 

 diameter and two inches long : but they diminished considerably 

 the size of the flame, and rendered it more liable to go out by 

 motion ; and the following experiments appear to show, that if 

 the diiimctcr of the u])pcr i:>rificc of the chinniey be not very 

 F f 2 large, 



