334 



Mr. Buddle on Mining Records. 



through the other drifts, and ascend the up-cast shaft without risk of coming 

 in contact with flame, 



Those drifts are called dumb furnaces by the colliers, in contra distinction 

 to the burning furnaces, and the drifts in the mine which carry the explosive 

 current to those dumb drifts are called c/as-pipe or pipe-drifts. Notwith- 

 standing the cooling effects of the air delivered into the up-cast shaft by 

 those dumb furnace-drifts, the burning furnace will keep the ascending 

 current, at the mouth of the up-cast shaft, generally, at a temperature of 

 about 90° of Far., which is quite sufficient to ensure a sufficient cur- 

 rent of air throua'h the workings. 



In twenty-five years' experience, I have only known one accident hap- 

 pen from the explosive mixture issuing from the dumb furnace being 

 ignited, but how the ignition took place could never be ascertained. 



The annexed Diagram shews this mode of ventilation. 



I have scarcely ever known an instance where it was necessary to put 

 out the burning furnace under this system, although it may have been 

 necessary to change the burning furnace occasionally from one drift to 

 another. 



More furnace-drifts than two are sometimes opened into the same up- 

 cast shaft. The Percy Pit, Percy-main Colliery, has four furnace-drifts in- 

 to the same up-cast shaft, all supplied by one down-cast, the main current 

 of atmospheric air from which, is divided into eight separate currents for 

 the ventilation of the workings. I merely mention this to shew that a 



