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which, I understand, thirty-eight men perished, leaving eighteen widows, and seventy children unprovided for.

Soon after this melancholy catastrophe, ten men perished at Killingworth by an explosion. And about the same time, seven men were instantly killed, and several severely wounded by an explosion at Fenton Park colliery. On the 25th of May, 1812, the colliery at Felling exploded, by which ninety-two persons were instantly destroyed, leaving forty-one widows, and one hundred and thirty-three children to the protection of the public.

And, upon the oth of October last, the Harrington Mill pit exploded, by which twenty-three people were killed, and many others severely wounded and scorched.

Thus, in the short space of seven years, upwards of two hundred pit-men were deprived, most suddenly, of their mortal existence, besides a great many wounded ; and upwards of three hundred women and children were left in a state of the greatest poverty and distress.

The great danger of these explosions, even when every precaution has been taken, is manifest by their frequency, and indeed it may be expected, that an explosion will take place by means of a lighted candle the instant that the hydrogen gas amounts to one-twelfth part of the atmospheric air present, and that a similar effect will follow at all proportions from one-sixth to one-twelfth.

When ventilation, by the methods in general use, is found insufficient to carry off the fire-damp, as it arises in coal mines, large pumps are employed at the top of the shaft for that purpose, which are worked by steam engines. So frequent and instantaneous are the changes in the proportions of inilammable air, from accidental circumstances, that it would be impossible at all times to ascertain, by a chemical process, at all parts of the mine, when danger is impending, for frequently the greatest differences of proportions exist at the same time, in different parts of such extensive works as coal mines. In fact, the miners know, from the appearance of the light of their candles, when the proportion of hydrogen gas is such, as to threaten an explosion; hence they carefully watch each other's candles, that they may desist in time, and escape instant destruction.

The excavations of coal mines are much greater than they are generally supposed to be: in some collieries they are constinued for many miles, forming numerous windings and turnings, along which the pit-men have frequently to walk for forty or fifty minutes before they arrive at the workings, during which time, as well as when at work, they have no direct communication with the surface of the earth, but are entirely at the mercy of their greatest enemy, the inflammable air. This circumstance first impressed me with the idea that the light, by which the pit-men were to work, might be insulated. I was well aware that no preparation of phosphorus could supply a sufficient light for the purpose; an observation equally applicable to the miserable scintillations of steel mills (as they are termed), which have often exploded the inflammable air of the coal mines.

I find it needful here to remark, that, as far as applies to myself, the idea of insulating the light, and also the plan which I have adopted for carrying this idea into effect, by the construction of the apparatus or lamp, are perfectly original. This lamp may be managed with the greatest ease by any MDCCCXIII,

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boy of common understanding. It is so strong, that should large pieces of coal fall upon it, they cannot in the least injure it. Nor is there any chance of its being upset by any acci- . dent, as it may be worked at the very bottom of the mine; and it is likewise conveniently portable.

The combustion of the candle, within the lamp, is supported by the ordinary atmospheric air of the coal mine, which is supplied by a pair of common bellows through a stratum of water below the candle; at the same time a portion of the air already in the lamp, is driven through another stratum of water above the candle, and thus the air supplied may explode within the body of the lamp, without communicating the effect to the air in the mine, however highly it might be charged with carburetted hydrogen gas.

The moment the air enters into the lamp, it comes in contact with the candle, and consequently, upon all orcasions, a small portion only of the air can be exploded, instead of the whole contents of the lamp; by these means several obvious advantages are secured. The air passing in a brisk current from below upward, close by the candle, carries the snuff with it, so that the light is always clear and steady.

I may also remark that wherever a person can exist from a sufficiency of atmospheric air, this lamp will afford a safe and abundant light, from one candle only, for the space of five hours at least. This lamp will, in all probability, be found very useful in the powder magazines of ships of war, and of forts, as also in those places where gunpowder is manufactured; but this observation is merely thrown out for the opinion of those who are more conversant upon such subjects.

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Philos. Trans. MDCCCXIII. Plate XV. p. 205.

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