DURHAM AND NORTHUMBERLAND.

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gate a A, into the headways K K, along whichit is forced by the boards and stoppings s s s s,and the stenting stoppings r r r r r, to thebottom of the upcast shaft.

Should the main stopping N be blown out,every working of the mine would be left un-ventilated, except the headway K K, alongwhich the current of air would pass directlyfrom the downcast to the upcast shaft. Norcould this be remedied until the stopping JSfwas replaced, leaving all the workmen in otherparts of the mine, particularly where the firehappened, to be suffocated by the choak andfire-damp.

It may be necessary to remind the readerthat this plate is merely sketched to elucidatethe lines of ventilation according to the presentsystem, and the variety of boards or workings,as it would otherwise carry with it too great anappearance of regularity and precision.

The floor of the mine is one continuedcourse of rugged substance, and, when passingfrom the downcast shaft towards the upcastshaft, continues to ascend according to the riseof the coal stratum: its sides and roof areequally rugged and irregular, and the wholepresents the most solitary and dismal aspectpossible to conceive.

By means of the foregoing system, ventirG