6 On preventing Accidents 



be urged against all the foregoing modes of obtaining light, 

 naiiiely, the pre- supposed want of a siifUcicnt quantity of 

 oxygen in the atmosphere; this, addetl to the positive had 

 qualities of the gases present in such situations, would 

 greatly endanger ihc health and lives of the workmen. 



Let us now turn our attention to the more practicable 

 iknd effectual plan of ventilation ; and in pursuing this sub- 

 ject we will commence with the first opening of a colliery. 

 It should be understood, that hydrogen and carbonic 

 acid ga<es are often met with in sinking shafts of consider- 

 able depth, as in many instances such are evolved for a 

 length of tiiTic in great quantities from fissures in tliestrara. 

 If two shafts are sunk near together, thrilling occasionally 

 through from one to the other is of great utility ; but in 

 some instances this is by no means sufficient to produce the 

 desired effect. Should this be the case, air-pipes of large 

 diameter must be extended from the bottom of the sinking 

 shaft, through the last thril into the adjoining shaft, in 

 the bottom of which, providing it is not deeper than the 

 thril last made, (in which case a scaffold will be necessary,) 

 a fire ought to be constantly kept burning: by this means 

 pure air will descend the sinking^ shaft, carrying with it the 

 extricated gases up the pipes into the adjoining shaft, 

 whose column of air will be rarefied by the fire. I conceive 

 this method to be superior to that of building a cupola, in 

 which a fire is placed, upon the ascending shaft; because, 

 if the chimnev be not somewhat near the size or diameter 

 of the shaft, the current of air will be impeded thereby. 

 Besides, a rarefied column of air in a deep shaft has a 

 greater tendency to produce a quicker current, than the 

 coluinn of air in a chimney, beyond doubt. 



When no communication can readily be had with an- 

 other shaft, it is somtlimcs customary to partition the 

 sinking shaft with boards down the middle. This, though 

 a simple, is an expensive plan; and if the temperature 

 occasioned by the workmen is the only means of pro- 

 ducing a circulation, how must it be carried on, when the 

 men are not at work ? I am aware that whsre there are 

 pumps working, these would, in some measure, remedy this 

 seeming defect, especially by occasionally turning or spill- 

 ing the water lificd down frouj the top to the bottom of 

 the shaft, for a short time. 



If wooden air-pipes, of about 15 inches diameter, are 

 put down the sinking shaft, and the upper ends of them are 

 fixed to the ash-pit of the engine boiler, (which, for an 

 engine capable of lifting the water of a deep shaft, is of 



considerable 



