a being the engine-shaft. But having witnessed the fatal consequences arising from the blowing out of the brattice by the explosion in the A Pit in 1820, I sunk the G Pit from the main coal to the Bensham Seam, in two separate shafts, leaving a division of solid stone between them as represented in the diagram. By this plan, I expected that, in the event of an explosion, the two separate shafts would give the blast a direct perpendicular line of direction, and prevent its blowing out the brattice above. It will, however, appear in the sequel that my expectation in this respect was not realized.
The darts on the plan of the colliery (Plate XVI.) shew the run of the different currents of air to the burning as well as the dumb furnaces. It will also be seen by the plan, that the workings were carried on upon the system of pannel-work, that is to say, in small divisions, separated by barriers of coal, so that the working and ventilating of the different divisions might be carried on, in a great degree, independently of each other.
The object of this mode of working was two-fold — to prevent the effect of any explosion which might happen in any one of these divisions from extending to other parts of the workings, and also to ensure a more effectual working of the pillars. The pillars had been worked out of several of those divisions, as shown on the plan, and as the goaf, or void, made by the working of the pillars could not be ventilated, those divisions became charged with gas, and all that could be done was to carry off the stream of gas issuing from them, by the pipe-drifts, through the dumb furnaces, into the up-cast shafts. Thus there were a number of capacious gasometers unavoidably standing charged, at all times, but as no naked lights were ever allowed to be taken into the pipe drifts, or up-cast shafts, little or no danger was apprehended; especially as the man doors[1], by which the wastemen had access to the pipe drifts, for the purpose of travelling and keeping them in repair, were double, and kept locked, the keys being kept by the master wastemen.
It is frequently necessary to alter the currents of air, but at the time of
this explosion the ventilation of the workings was effected by two up-cast and three down-cast shafts. The A and B Pits were the up-casts, the C
- ↑ Man doors, small doors, or valves, placed in air stoppings, barely of sufficient size to allow a man to creep through.
