S8 On venlilnttng Coal-pits. 



In this channel think of ]\lr. Farey and his associates P This is 

 indeed n bad reception, and a sad return towards those who sa- 

 crifice their ineans, and direct their time and talents towards 

 ' a Gonsiunmation so devoutly to be wished.' Certainly, there 

 is no renuuieration but that wholesome return which springs up 

 in the breast, when it ajiproves the labour. 



" It surely must be apparent to every one the least conversant 

 with chemical jjhilosophv, that the sparks from a steel milf, 

 Tvhich serve to guide the miner in exploring the workings, can 

 afford him no certain security. I confess that the recommenda' 

 tion of Sir H. Davy, for employing red hot charcoal (not exhibit- 

 ing flame) when his lamp can no longer burn, was one which 

 startled me. What is the consequence of such a substitute ? An 

 exchange of carbonated hydrogen for carbonic acid gas. — Fire 

 dUmp is supplanted by c/ioke damp — we escape Scylla to siiffer 

 by Charybdis. The question has somewhat of the complexion of 

 the antidote proposed for accidents by fire in the theatres. The 

 good people were calmed by the comJ'ortaLle assurance, that in 

 such an occurrence the managers could drown the pit in a few 

 minutes ! Thus, then, we want a lamp to guide us when such 

 a desideratum is most needed. This is amply afforded by a pro- 

 position which II published in my ' Elements of Chemical Sci- 

 ence,' in August last, for bringing the atmospheric air from the 

 stratum of air contiguous to the floor of the mine, taking advan- 

 tage of the ascending carburctted hydrogen : — this I proposed to 

 do by a flexible tube. My latest improvement of the chimney 

 was a spiral tube, having a central sphere. I have since applied 

 a small lever with a delicate ball at each extremity — this ope- 

 rates in the hollow sphere, and so long as a free current is main- 

 tained, the ball hangs in medio ; but should unforeseen circum- 

 stances, on which it is impossible to calculate, occasion the flame 

 to ascend, the air which it propels before it, occasions the ball to 

 rise, and shut the upper aperture; and again, should a current 

 descend, the ball will, by the impulse, fall, and shut the under 

 aperture. That the projection of this lamp rested with me in 

 point of priority, I have clearly proved, a?id not with Dr. ISlurray 

 of Edinburgh. I lay this claim, therefore, as the first who pub- 

 licly proposed an air-tight lamp, to be fed by air brought from 

 the floor of the mire. The mere aperture at top, instead of the 

 chimney, as proposed bv Dr. M., gives no assurance of security 

 whatever. However convinced I may be of the certain safety of 

 the spiral chimney, independent of the lever, still I have wished 

 to make 'assurance doubly sure,' by providing against any pos- 

 sible casualty. My claims of this priority, and a description of 

 a simple and efficacious air-tight stove for drawing off the car- 

 bonated hydrogen as it fojuis in mines, with an easy mode of 



getting 



