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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 Commonsf, 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.
f 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 combustion; but to know what quantity was necessary, I had a slide at the bottom of the first tube in my lamp, to admit such a quantity of air as might eventually be found necessary to keep up the combustion.” Stephenson then, accompanied by his friend Wood, went to Newcastle, and ordered a lamp to be made according to the prepared plan, by Messrs. Hogg, tinmen, at the head of the Side — a well-known street in Newcastle. At the same time, they ordered a glass to be made for the lamp, at the Northumberland Glass House, in the same town. This lamp was received from the makers on the 21st of October, and was taken to Killingworth for the purpose of immediate experiment. George Stephenson arrived home about dusk, and found Moodie, the under viewer, all anxiety, waiting for him at the cottage. The lamp was immediately filled with oil, trimmed, and lighted; and all was now ready for its trial in the pit. But Mr. Wood had not yet arrived, and it was thought necessary that he should be present. He was known to be at Benton, about a mile distant. “Robert,” said George, turning to his son, “you must go over for Wood, and tell him to come directly.” It was a dark night; but the boy had learnt implicitly to obey his father, and he set out forthwith. On his way he had to pass through Benton churchyard, and as he cautiously approached the wicketgate and opened it, he thought he saw a white figure standing amongst the tombs He started back, his heart fluttering, and, making the circuit of the wall of the buryingground, he came round on the other side; and then he saw that the supposed white figure had been caused by a lanthorn flashing its light upon the grave-digger, who was busy plying his vocation at that late hour. Mr. Wood was soon found, and, mounting his horse, he rode over to Killingworth at once. When Robert reached the cottage, he found his father had just left (it was then near eleven o'clock), and
cHAP. x.] HIS COURAGE IN TESTING THE LAMP. 107
gone down the shaft for the purpose of trying the lamp in one of the most dangerous parts of the mine !
Arrived at the bottom of the shaft with the lamp, the party directed their steps towards one of the foulest galleries in the pit, where the explosive gas was issuing through a blower in the roof of the mine with a loud hissing noise. By erecting some deal boarding around that part of the gallery into which the gas was escaping, the air was thus made more foul for the purpose of the experiment. After waiting for about an hour, Moodie, whose practical experience of fire-damp in pits was greater than that of either Stephenson or Wood, was requested by them to go into the place which had thus been made foul; and, having done so, he returned, and told them that the smell of the air was such, that if a lighted candle were now introduced, an explosion must inevitably take place. He cautioned Stephenson as to the danger, both to themselves and to the pit, if the gas took fire. But Stephenson declared his confidence in the safety of his lamp, and, having lit the wick, he boldly proceeded with it towards the explosive air. The others, more timid and doubtful, hung back when they came within hearing of the blower; and apprehensive of the danger, they retired into a safe place, out of sight of the lamp, which gradually disappeared with its bearer, in the recesses of the mine. It was a critical moment; and the danger was such as would have tried the stoutest heart. Stephenson, advancing alone, with his yet untried lamp, in the depths of those underground workings, calmly venturing his own life in the determination to discover a mode by which the lives of many might be saved and death disarmed in these fatal caverns,—presented an example of intrepid nerve and manly courage, more noble even than that which, in the excitement of battle and the collective impetuosity of a charge, carries a man up to the cannon's mouth.
Advancing to the place of danger, and entering within the fouled air, his lighted lamp in hand, Stephenson held it firmly out, in the full current of the blower, and within a few inches of its mouth ! Thus exposed, the flame of the lamp at first increased, and then flickered and went out; but there was no explosion of the gas. Stephenson returned to his companions, who were still at a distance, and told them what had occurred. Having now acquired somewhat more confidence, they advanced with him to a point from which they could observe him repeat his experiment, but still at a safe distance. They saw that when the lighted lamp was held within the explosive mixture, there was a great flame; the lamp was almost full of fire; and then it smothered out. Again returning to his companions, he relighted the lamp, and repeated the experiment. This he did several times, with the same result. At length Wood and Moodie ventured to advance close to the fouled part of the pit; and, in making some of the later trials, Mr. Wood himself held up the lighted lamp to the blower. Such was the result of the first experiments with the first practical Miner's Safety Lamp; and such the daring resolution of its inventor in testing its valuable qualities.
Before leaving the pit, Stephenson expressed his opinion that, by an alteration of the lamp, which he then contemplated, he could make it burn better. This was by a change in the slide through which the air was admitted into the lower part of the lamp, under the flame. After making some experiments on the air collected at the blower, by means of bladders which were mounted with tubes of various diameters, he satisfied himself that, when the tube was reduced to a certain diameter, the explosion would not pass through ; and he fashioned his slide accordingly, reducing the diameter of the tube until he conceived it was quite safe. In the course of about a fortnight the experiments were repeated in the pit,