mi te mae vis preserved. Seriensen vas mated to the writer. me te men. As Heppel, who had lees a 1 mi lepel a budy the brick workmen valy vici te iz vas surek, though several w un sufleuzei ʼn the pin Hengel relaces that, when down The put some trs aut seing us he dead bodies, the cause of the alert vis de subject of some scaversation derveen himself and Sternenson, ai Herrei then asked him, “Un pag te lune revene sich will becurrences ?" Stundeasca mended mat he digitsmething might be done. Then,” sud Her vil the solder you start the better; for the price of song ▼ionen ́s „res," The ther thees to be attained was to devise a lamp that we'd bum and give detà sufficient light so guide the miner in bis underground labears with at communicating flame to the indimmulle is with semulated in certain parts of the pla* Something had already been attempted towards the invention of a ecllery lamp by Dr. Clanny, of Sunderland, who, in 1813, contrived an apparatus to which he gave air from the mine through water, by means of bellows. This lamp went out of itself in inflammable gas. It was found, however, too unwieldy to be used by the miners for the pur The common means employed by the miners for lighting those parts of the mine where danger was apprehended from the fire-damp, was by a steel wheel, which, being made to revolve in contact with fint, afforded a succession of sparks; but the apparatus always required a person to work it; and though much less liable to explode the tire-damp than a common candle, yet its use was not altogether free from danger, and the light which it gave forth was very metlicient CHAP. X.] MEDITATES A SAFETY LAMP. 103 poses of their work. A committee of gentlemen was formed at Sunderland to investigate the causes of the explosions, and to devise, if possible, some means of preventing them. At the invitation of that committee, Sir Humphry Davy, then in the full zenith of his reputation, was requested to turn his attention to the subject. He accordingly visited the collieries near Newcastle on the 24th of August, 1815*; and at the close of that year, on the 9th of November, 1815, he read his celebrated paper "On the Fire-Damp of Coal Mines, and on Methods of lighting the Mine so as to prevent its Explosion," before the Royal Society of London.† But a humbler, though not less diligent and original, thinker had been at work before him, and had already practically solved the problem of the Safety Lamp. Stephenson was of course well aware of the anxiety which prevailed in the colliery districts as to the invention of a lamp which should give light enough for the miner's work without exploding the fire-damp. The painful incidents above described only served to quicken his eagerness to master the difficulty. Let the reader bear in mind the comparative obscurity of Stephenson's position, for he was as yet but one step removed from the grade of a manual labourer, the meagreness of his scientific knowledge, all of which he had himself gathered bit by bit during his leisure moments, which were but few,—his almost entire lack of teachers, excepting his own keen and observant eye and his shrewd and penetrating judgment; let these things be remembered, and the invention of the Geordy Safety Lamp by Stephenson will be regarded as an achievement of the highest merit. For several years he had been engaged, in his own rude way, in making experiments with the fire-damp in the Kil * Paris's Life of Davy, 4to ed. p. 310. † Ibid. p. 315. lingworth mine. The pitmen used to expostulate with him on these occasions, believing that the experiments were fraught with danger. One of the sinkers, called M'Crie, observing him holding up lighted candles to the windward of the "blower" or fissure from which the inflammable gas escaped, entreated him to desist; but Stephenson's answer was, that "he was busy with a plan by which he could make his experiments useful for preserving men's lives." On these occasions the miners usually got out of the way before he lit the gas. In 1815, although he was very much occupied with the business of the collieries and with the improvements in his new locomotive engine, he was also busily engaged in making experiments on inflammable gas in the Killingworth pit. As he himself afterwards related to the Committee of the House of Commons†, which sat on the subject of Accidents in Mines in 1835, the nature and object of those experiments, we cannot do better than cite his own words: "I will give the Committee," said he, "my idea mechanically, because I knew nothing of chemistry at the time. Seeing the gas lighted up, and observing the velocity with which the flame passed along the roof, my attention was drawn to the contriving of a lamp, seeing it required a given time to pass over a given distance. My idea of making a lamp was entirely on mechanical principles; and I think I shall be found quite correct in my views, from mechanical reasoning. I knew well that the heated air from the fire drove round a smoke-jack, and that caused me to know that I could have a power from it. I also knew very well that a • Evidence given before the Committee appointed to report upon the claims of George Stephenson, relative to the invention of his Safety Lamp. Hodgson: Newcastle, 1817, p. 21. † Report. Accidents in Mines, with Evidence. (Parliamentary Paper 603. Session 1835.) CHAP. X.] HIS EXPERIMENTS ON FIRE-DAMP. 105 steam-engine chimney was built for the purpose of causing a strong current of air through the fire. Having these facts before me, and knowing the properties of heated air, I amused myself with lighting one of the blowers in the neighbourhood of where I had to erect machinery. I had it on fire; the volume of flame was coming out the size of my two hands, but was not so large but that I could approach close to it. Holding my candle to the windward of the flame, I observed that it changed its colour. I then got two candles, and again placed them to the windward of the flame: it changed colour still more, and became duller. I got a number of candles, and placing them all to the windward, the blower ceased to burn. This then gave me the idea, that if I could construct my lamp so as, with a chimney at the top, to cause a current, it would never fire at the top of the chimney; and by seeing the velocity with which the ignited fire-damp passed along the roof, I considered that, if I could produce a current through tubes in a lamp equal to the current that I saw passing along the roof, I should make a lamp that could be taken into an explosive mixture without exploding externally." Such was Mr. Stephenson's theory, when he proceeded to embody his idea of a miner's safety lamp in a practical form. In the month of August, 1815, he requested his friend Mr. Nicholas Wood, the head viewer of the colliery, to prepare a drawing of a lamp, according to the description which he gave him. After several evenings' careful deliberations, the drawing was prepared, and it was shown to several of the head men about the works. " My first lamp," said Mr. Stephenson, describing it to the Committee above referred to, "had a chimney at the top of the lamp, and a tube at the bottom, to admit the atmospheric air, or fire-damp and air, to feed the burner or combustion of the lamp. I was not aware of the precise quantity required to feed the com lingworth on these fraught w observin the "blow escaped, en was, that his experi the gas. business new loco experime he himsel of Comm in 1835, not do b 66 " I W chanicall Seeing t which t drawn t time to lamp w shall be reasoni drove r I could • Evi of Geor Newcast ↑ Rep Session ', |