Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne 1838 Vol.2.djvu/397

 the dumb furnace drifts. The drifts of communication between the dumb furnace drifts, and the workings were called gas-pipe drifts, because they were subject to be charged, and generally were charged with an explosive current. Those gas-pipe drifts were only travelled by the wastemen for the purpose of repairing and keeping them in good order, and no light except the Davy lamp was ever used in them. For the more effectual ventilation of the Bensham workings, four pits, the A, B, C, and G, Pits, had been sunk to it. See the plan, Plate XVI.

The A and B were the up-casts, powerful furnaces being placed at their bottom, and the C and G. were the down-casts. Each up-cast pit had its furnace supplied by a current of inexplosive air from the workings of the the whole coal, while the dumb furnace drift at the B Pit carried off the contaminated current from the pillar working, the dumb furnace drift at the A Pit not having been completed at the time of the accident.

The G Pit had been sunk to the High-main Seam 13 feet diameter, and was divided into two coal and one engine-shaft, by a three-tailed brattice; thus