I return Dr. Paris's letter, and shall briefly answer his enquiries.
If the Davy lamp was exclusively used, and due care taken in its management, it is certain that few accidents would occur in our coal mines; but the exclusive use of the "Davy" is not compatible with the working of many of our mines, in consequence of their not being workable without the aid of gunpowder.
In such mines, where every collier must necessarily fire, on the average, two shots a-day, we are exposed to the risk of explosion from the ignition of the gunpowder, even if no naked lights were used in carrying on the ordinary operations of the mine.
This was the case in Jarrow Colliery, at the time the late accident happened. As the use of gunpowder was indispensable, naked lights were generally used, and the accident was occasioned by a 'bag' of inflammable air forcing out a large block of coal, in the face of a drift, from a fissure in which it had been pent up, perhaps from the Creation, and firing at the first naked light with which it came in contact, after having been diluted down to the combustible point by a due admixture of atmospheric air.
As to the number of old collieries and old workings which have been renovated, and as to the quantity of coal which has been, and will be saved to the public by the invention of the "Davy," it is scarcely possible to give an account, or to form an estimate.
In this part of the country, 'Walker's Colliery,' after having been completely worked out, according to the former system, with candles and steel-mills, and after having been abandoned in 1811, was reopened in 1818 by the aid of the "Davy" and has been worked on an extensive scale ever since, and may continue to be worked for an almost indefinite period.
Great part of the formerly relinquished workings of Wall's-end, Willington, Percy-main, Hebburn, Jarrow, Elswick, Benwell, &c. &c., as well as several collieries on the Wear, have been recovered, and are continued in work by the invention of the "Davy."
If I had only what you know perfectly well I have not—Time, I could write a volume on this subject.
I shall shortly, through the medium of a friend, get an important paper on the subject of the "Davy," put into Dr. Paris's hands.
Believe me, my dear Sir Cuthbert,
To remain yours very faithfully,
John Buddle.