DURHAM AND NORTHUMBERLAND. 33

When the. gas escapes only in regular andmoderate quantities, the miner may explode itas he goes on, without producing any othereffect than a pleasing phosphoric phenomenain the working, or a flash like the flash of amusket. But this, after being practised foryears, unfortunately strengthens the idea ofsecurity, and the mind is incapable of inform-ing itself what hidden reservoirs may bebroken into in the future progress of a mine.A fact so simple, and yet so incontrovertibleas this, can but impress every one with con-viction, and produce the natural inference, thatthe most desirable and most valuable improve*ment in a colliery would be afforded by aninvention to counteract this operation of nature.

The real origin of gas, however, still forms asubject for the inquiries of philosophy. As noconclusive evidence has ever yet established acertain cause, some ascribe it to the gradualdecomposition of coal, which in consequencegives out its carburetted hydrogen, or inflam-mable air; others, who suppose that the forma-tion of coal was produced by the decompositionand concretion of vegetable substances, inferthat it originates from the exhalation of putre-fying animal and vegetable matter in the stag-nant water of coal mines; others, to the effect

B