yards above the top of the pit; and through this tube the said damp air has ever since discharged itself without being sensibly diminished in its strength, or lessened in its quantity, since it was first opened, which is now two years and nine months ago. It is just the same in summer as in winter, and will fill a large bladder in a few seconds, by placing a funnel at the top of the tube, with the small end of it put into the neck of the bladder, and kept close with one's hand.

"The said air being put into a bladder, as is above described, and tied close, may be carried away, and kept some days, and being afterwards pressed gently through a small pipe into the flame of a candle, will take fire, and burn at the end of the pipe as long as the bladder is gently pressed to feed the flame, and when taken from the candle, after it is so lighted, it will continue burning till there is no more air left in the bladder to supply the flame. This succeeded in May last, before the Royal Society, after the air had been confined in the bladder for near a month.

"The air when it comes out at the top of the tube is as cold as frosty air.

"It is to be observed, that this sort of vapour, or damp air, will not take fire except by flame; sparks do not affect it, and for that reason it is frequent to use flint and steel in places affected with

this sort of damp, which will give a glimmering light, that it is a great help to the workmen in difficult cases.

"After the damp air was carried up in a tube, in the manner above described, the pit was no more annoyed with it, but was sunk very successfully through several beds of stone and coal, without any other accident or interruption till it came to the main seam of coals, which is three yards thick, and 79 fathom deep from the surface; and the said pit being oval, viz. ten foot one way, and eight the other, it serves both for draining the water by a fire engine, and also for raising the coals.

"Whitehaven, August 1, 1733.”

It will be observed, that the writer of this narration has described with remarkable minuteness and precision the principal properties of coal gas; and as he exhibited them to different members of the Royal Society, and evinced that the gas retained its elasticity and inflammability after keeping it for some time. But notwithstanding these striking appearances, there seems to be no evidence that the philosophers of that period undertook any experiments with the view of applying it to useful purposes, or even suggested any such idea to the world.

CHAPTER III.

DR. JOHN CLAYTON'S ACCIDENTAL DISCOVERY OF THE INFLAMMABILITY OF COAL GAS; THE EXPERIMENTS OF DR. RICHARD WATSON, &c.

He

One of those fortuitous occurrences, however, which have often led to important discoveries, was the occasion of the properties of coal gas being better known and more particularly attended to. The circumstance is detailed in the Philosophical Transactions for 1739, in an "Extract from a Letter by the Rev. Dr. John Clayton."* calls the gas "the spirit" of coal, and discovered that it was inflammable, from its having accidentally caught fire by coming in contact with a candle, as it was escaping from a fracture in one of his distillatory vessels, while he was endeavouring to repair the luting. He has carefully enumerated the several substances produced by his distillation; and by preserving the gas in bladders he

* The original manuscript is in the British Museum, Ayscough's MSS. 4437, and is stated to be an extract from a letter to the Hon. Robert Boyle, communicated in 1739 to the Earl of Egmont, F. R. S., by Dr. Robert Clayton, Bishop of Cork and Orrery. The date of the letter is not given; but it must have been written many years before, because Mr. Boyle died in 1691. Dr. John Clayton was Dean of Kildare, in Ireland.

frequently diverted his friends by exhibiting its inflammability when lighted by a candle. The following is Dr. Clayton's own clear and impressive narrative of his discovery:

"Having seen a ditch within two miles of Wigan, in Lancashire, wherein the water would seemingly burn like brandy, the flame of which was so fierce that several strangers have boiled eggs over it, the people thereabouts, indeed, affirm that about thirty years ago, it would have boiled a piece of beef; and that whereas much rain formerly made it burn fiercer, now after rain it would scarcely burn at all. It was after a longcontinued season of rain that I came to see the place, and make some experiments; and found accordingly that a lighted paper, though it were waived all over the ditch, the water would not take fire. I then hired a person to make a dam in the ditch, and fling out the water, in order to try whether the steam which arose out of the ditch would then take fire, but found it would not. I still, however, pursued my experiment, and made him dig deeper; and when he had dug about the depth of half a yard, we found a shelly coal, and the candle being then put down into the hole, the air catched fire and continued burning.

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I got some coal, and distilled it in a retort in an open fire. At first there came over only phlegm, afterwards a black oil, and then,

likewise, a spirit arose which I could no ways condense; but it forced my lute and broke my glasses. Once when it had forced my lute, coming close thereto, in order to try to repair it, I observed that the spirit which issued out caught fire at the flame of the candle, and continued burning with violence as it issued out in a stream, which I blew out, and lighted again alternately several times. I then had a mind to try if I could save any of this spirit; in order to which I took a turbinated receiver, and putting a candle to the pipe of the receiver, whilst the spirit arose, I observed that it catched flame, and continued burning at the end of the pipes, though you could not discern what fed the flame. I then blew it out, and lighted it again several times; after which I fixed a bladder, squeezed and void of air, to the pipe of the receiver. The oil and phlegm descending into the receiver, but the spirit still ascending, blew up the bladder. I then filled a good many bladders therewith, and might have filled an inconceivable number more; for the spirit continued to rise for several hours, and filled the bladders almost as fast as a man could have blown them with his mouth; and yet the quantity of coals distilled was inconsiderable. "I kept this spirit in the bladders a considerable time, and endeavoured several ways to condense it, but in vain; and when I had a mind to