Several persons concerned in coal mines, for whose opinions I entertain much respect, expressed a desire that a safety lamp might be constructed, which would feed itself with atmospheric air for combustion without the aid of bellows ; and in order that such a desideratum might be supplied, I had the pleasure in November last, (1815) to discover, when experimenting with the original safety lamp, in an atmosphere of fire damp at the Herrington mill pit, that when I accidentally used hot water, the fire damp burned silently at the wick of the oil lamp, and did not explode within the original safety lamp as formerly, which was the principle of its safety. I accordingly instituted a series of experiments, and invariably found, that by the intervention of steam the fire damp might be burnt, without explosion, to any extent, at the wick. This extraordinary and unexpected discovery induced me to turn over the leaves of the seventh edition of Dr. Henry's Elements of Experimental Chemistry, in which I observed a reference to some experiments by Von Grotthus upon hydrogen gas, the original of which are therein stated to be inserted in the 82 Vol. of the Annales de Chemie ; and by the kindness of a distant friend I was afterwards enabled to peruse that volume, in which I found a complete corroboration of my experiments upon steam and hydrogen.

In the month of December of the same year, after many tedious experiments, I constructed my steam safety lamp, which I then shewed to the Society for preventing accidents in coal mines, for which I had also the honour to receive their unanimous thanks. I intimated to the society at the same time, that in this lamp the light was given partly from oil, and partly from the fire damp when used in the mines.

The steam lamps are constructed of the strongest tinned iron, with flint glass in front, 3-8 of an inch in thickness ; from which it will be readily understood, that these lamps will bear any sort of usage. The steam safety lamps require no trouble or particular attention from the miner when he is using them, and are by no means expensive, and exceedingly durable : and I will venture to assert, that with these lamps no accident whatever can arise in any place, or under any circumstances, let the state of the mine be ever so deplorable from fire damp.

In the steam safety lamp, the atmospheric air of the coal mine passes in a current through a tube, and is mixed with steam before it can possibly arrive at the light : by this means the fire damp burns silently and steadily at the wick of the lamp alone, for any length of time. Should it exceed the due proportion of atmospheric air for supporting combustion, the light of course goes out; but in this lamp such an event will seldom happen. It has also the valuable quality of keeping cool throughout every part, and under all circumstances, by reason of the steam, which is constantly extricated and kept in motion within the lamp. And as steam is merely water 1800 times expanded, there is no cause to dread the want of a sufficient supply of this useful agent.

No current of air containing fire damp, and suspending coal dust, gunpowder, or pyrites in powder, can do any mischief, which may at once be understood by a slight examination of the steam safety lamp. whilst the light is always uniform, steady, and bright. It is now well know, that this lamp burns most brilliantly in an atmosphere of fire damp, after the wire gauze lamps go out, and even after the original safety lamp has had the fire damp exploded within in, as acknowledged by Messrs. Watkin and Wood, viewers, and Mr. Patterson, to have occurred not long since at the Engine Pit in this county. For without my safety lamps, the workmen must have been left in darkness in that well known pit.

No lamp supplying itself with air can be considered as perfectly secure without steam : and it is a curious circumstance that as water was the medium of safety in the original lamp, so water in the form of steam has since become most useful for our present purpose, in affording a permanent light, wherever there is a sufficient quantity of oxygen to support combustion.

My steam safety lamps have been much used in the Herrington mill pit, the White-field pit, and the Engine pit, where their value is duly appreciated.

I beg it may be understood, that my letter, No. V, at page 130 of Mr. Holmes' book on Coal Mines, was a private communication, and never intended to meet the public eye ; but by a mistake on the part of the publisher, it was inserted unknown to me, for which I am truly sorry, as I never intended to wound the feelings of any individual. Mr. Holmes of his own accord has expressed his determination to leave this letter out, in the next edition of his work.

Upon the 6th of this month, I had the honour to receive spontaneously and unanimously the thanks of the Society for preventing accidents in coal mines, for my general services.

From the increasing confidence with which my steam safety lamps are received by those gentlemen who are concerned in the management of coal mines, I have reason to expect, that in a short time they will be universally employed.