Explosions in Coal Mines. 29 



another, from 6 to 15 feet of explosive mixture, which would 

 afterwards have to be carried out of the works by the usual 

 mode of ventilation. 



In the first place, we propose that the pillars and jnds should 

 be so worked and drawn as to have reference to the form which 

 it is desirable to give to the goaf. This form must be depend- 

 ent on circumstances, but the point required is that it should 

 draw together at its termination in the upper part of the works, 

 i. e. that as the strata rise, the goaf should not have several 

 projections or bays, running independently into the higher 

 works, but one only where the highest point of the goaf basin 

 ma}' occur, and towards which all the fire-damp in the goaf 

 may drain and tend to run under. It is as if in making a 

 pond on the side of a hill, — there should not be two or three 

 low places on the bank where the superfluous water may run 

 over, but one only, that being the lowest, as in the fire-damp 

 case it would require to be the highest. This condition would 

 probably be obtained with facility by continually keeping one 

 jud drawn in advance of the rest; and the inspection of a 

 working plan with the inclines drawn on it would easily deter- 

 mine, in every case, what should be done. The next point is 

 to drain or clear this place as well as may be of its fire-damp, 

 which if it could be done effectually, would, in all probability, 

 prevent danger from the goaf, if not absolutely, yet to an ex- 

 tent far beyond what is the case at present ; and for this pur- 

 pose two plans suggest themselves, the same in principle, but 

 differing in extent. 



The first plan consists in laying a pipe from the goaf to the 

 upcast shaft, introducing the one extremity into the vault of 

 the goaf at the upper edge of its brim, and furnishing the 

 other extremity with necessary means of drawing the air out 

 of the pipe. The pipe itself may be of cast iron in lengths, 

 joined together with sockets and caulked joints, or in any 

 other of the many well-known manners : its diameter may be 

 about 12 inches, until experience may have directed some 

 other dimensions. Its place, for the chief part of its course, 

 would probably be in the return way; for it ought to be tight, 

 having no other opening than the two extremities ; and in the 

 return way it could be best examined from time to time, and 

 would be safest from the effects of creep. 



The exit or upcast end of the pipe is to be supplied with 

 means of draught or suction ; this might be either a blowing 

 cylinder, or a rough box double bellows, or a revolving fanner, 

 any of which might be worked by the engine, or even by a 

 man or boy, for the work would be easy, there being no re- 

 sistance to the exit of the air analogous to that offered by tlie 



