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any cause to regret the countenance and support which you have so generously afforded me.” That Stephenson amply fulfilled this promise and pledge to his friends, his future career abundantly proved.
But what said Sir Humphry Davy as to this testimonial presented to Stephenson for having invented the safety lamp ? In a private letter*, written at the time, he characterised as “ infamous” the resolutions adopted by Mr. Stephenson's supporters, alleging that he had only “pirated” his invention. “ It will turn out,” said he, alluding to the Stephenson testimonial, “a very disgraceful business for the persons who have agitated it ;” and in another letter he said, “ there never was a more gross imposture than that of Stephenson.” To his friend Sydney Smith, he seems to have spoken of the Killingworth engine-wright as “a spurious Aladdin.” f.
Whilst Sir Humphry Davy spoke thus bitterly in his private letters, it is somewhat remarkable that he never once in his published papers on the subject alluded to the fact that Mr. Stephenson had constructed and tested a safety lamp in the mine, months before his own was invented, although, as appears from a private letter since published by Dr. Paris in his “Life of Davy," he was aware of the fact. Nor did he refer to Humboldt's contrivance of a safety lamp in 1796, on a plan similar to that afterwards adopted by Dr. Clanny. Indeed, the manner in which he alluded to the last-named gentleman, who was the first to show Sir. H. Davy a safety lamp, imperfect though it might be, was considered very disrespectful by Dr. Clanny and his friends.
Now that all angry feelings between the contending parties have softened down, it is not perhaps very difficult to
* Since published in the Mechanics' Magazine, vol. liv. p. 423.
Journal des Mines, tom. viii. p. 839.
THE TUBE LAMP.
get at the truth of this controversy. From what we have stated, we think it must be admitted that the fact that carburetted hydrogen will not explode down narrow tubes, was discovered by Stephenson, and that this fact or principle was applied by him in the invention of three successive lamps constructed under his directions, all perfectly safe. Sir Humphry Davy discovered the same fact about the same time, but most probably at a subsequent date, and afterwards constructed a safety lamp which was preferred to that of Stephenson, on account of its greater cheapness and lightness. Sir H. Davy himself acknowledges that the merit of his lamp rested entirely on the discovery of the principle referred to, which had previously been ascertained and verified by the repeated experiments of Mr. Stephenson.
However great the merits of Mr. Stephenson in connection with the invention of the tube safety lamp, they cannot be regarded as detracting from the distinguished reputation of Sir Humphry Davy. His inquiries into the explosive properties of carburetted hydrogen gas were thoroughly original; and his discovery of the fact that explosion will not pass through tubes of a certain diameter, was doubtless made independently of all that Stephenson had done in verification of the same fact. . It even appears that Mr. Smithson Tennant and Dr. Wollaston had observed the same fact several years before*, though neither Stephenson nor Davy knew it while they were prosecuting their experi·ments. Sir Humphry Davy's subsequent modification of the tube lamp, by which, while diminishing the diameter, he in the same ratio shortened the tubes without danger, and in the form of wire-gauze enveloped the safety lamp by a multiplicity of tubes, was a beautiful application of the true theory which he had formed upon the subject. “ The whole theory
* Paris's Life of Davy, 4to ed., p. 316., and note to Davy's Paper read before the Royal Society, November 9th, 1815.
and operation of the safety lamp,” says Davy's biographer*, “is nothing more than an apparatus by which the inflammable air, upon exploding in its interior, cannot pass out without being so far cooled, as to deprive it of the power of communicating inflammation to the surrounding atmosphere. The principle having been once discovered, it was easy to adopt and multiply practical applications of it. From the result of these researches it became evident, that to light mines infested with fire-damp, with perfect security, it was only necessary to use an air-tight lanthorn, supplied with air from tubes of small diameter, through which explosions cannot pass, and with a chimney on a similar principle at the upper part to carry off the foul air. A common lanthorn, to be adapted to the purpose, merely required to be made air-tight in the door and sides, and to be furnished with a chimney, and the system of safety apertures below and above the flame of the lamp. Such, in fact, was Davy's first safety lamp; and having afterwards varied the arrangements of the tubes in different ways, he at length exchanged them for canals, which consisted of close concentric hollow metallic cylinders, of different diameters, so placed together as to form circular canals of the diameter of from one twenty-fifth to one fortieth of an inch, and of an inch and seven tenths in length.” Carrying out the same principle, the idea occurred to him of constructing the lamp entirely of wire-gauze, with apertures of from one fortieth to one sixtieth of an inch in diameter. A lamp so constructed was exhibited in January, 1816, and shortly after came into general use.
The increased number of accidents which have occurred from explosions in coal mines f since the general introduction
• Paris's Life of Davy, 4to ed., p. 317.
† In the eighteen years previous to the introduction of the lamp, 447 persons lost their lives in the counties of Durham and Northumberland, whilst in the eighteen years following, the fatal accidents amounted to 538. — Report on
of the Davy lamp, have led to considerable doubts as to its safety, and to inquiries as to the means by which it may be further improved; for experience has shown that, under certain circumstances, the Davy lamp is not safe. Mr. Stephenson was of opinion that the modification of his own and Sir Humphry Davy's lamp, combining the glass cylinder with the wire-gauze, was the most secure lamp; at the same time it must be admitted that the Davy and the Geordy lamps alike failed to stand the severe tests to which they were submitted by Dr. Pereira, when examined before the Committee on Accidents in Mines. Indeed, Dr. Pereira did not hesitate to say, that when exposed to a current of explosive gas, the Davy lamp is “ decidedly unsafe," and that the experiments by which its safety had been “demonstrated" in the lecture-room had proved entirely “fallacious."* The Committee, in their report, make use of these words: “ Accidents have occurred when his (Sir H. Davy's) lamp was in general and careful use; no one survived to tell the tale of how these occurrences took place; conjecture supplied the want of positive knowledge most unsatisfactorily; but incidents are recorded which prove what must follow unreasonable testing of the lamp; and your Committee are constrained to believe that ignorance and a false reliance upon its merits, in cases attended with unwarrantable risks, have led to disastrous consequences.”
It is worthy of remark, that under circumstances in which the wire-gauze of the Davy lamp becomes red-hot from the high explosiveness of the gas, the Geordy lamp is extinguished; and we cannot but think that this fact testifies to the de
Accidents in Mines, 1835, p. iv. The increase in the number of fatal accidents was no doubt in a great measure attributable to the circumstance that, after the invention of the safety lamp, the working was resumed in many dangerous mines, which had formerly been abandoned. * Report on Accidents in Mines, p. 296. Evidence of Dr. Pereira, F.L.S.
cidedly superior safety of the Geordy. An accident occurred in the Oaks Colliery Pit at Barnsley, on the 20th of August, 1857, which strikingly exemplified the respective qualities of the lamps. A sudden outburst of gas took place from the floor of the mine, along a distance of fifty yards. Fortunately the men working in the pit at the time were all supplied with safety lamps — the hewers with Stephenson's, and the hurriers with Davy's. Upon this occasion, the whole of the Stephenson lamps, over a space of five hundred yards, were extinguished almost instantaneously; whereas the Davy lamps were filled with fire, and became red-hot — so much so, that several of the men using them had their hands burnt by the gauze. Had a strong current of air been blowing through the gallery at the time, an explosion would most probably have taken place, — an accident which, it will be observed, could not, under such circumstances, occur from the use of the Geordy, which is immediately extinguished so soon as the air becomes explosive.
The merits of Dr. Clanny of Sunderland in connection with the invention of his lamp were considerable; yet a long period elapsed before they were publicly recognised. In 1846, however, a subscription was set on foot by his friends for the purpose of presenting him with a testimonial, and Mr. Stephenson was found amongst the list of subscribers. On sending in his contribution, he said, “I believe Dr. Clanny was the first person who made the attempt to construct a lamp which should burn in an inflammable atmosphere without exploding. Such a lamp was made by Dr. Clanny, although it was not proved practicable to manage in coal mines. Nevertheless, I think great merit is due to him for what he did, and you may therefore put my name down for five pounds towards his testimonial.”