CHAPTER XIV.

THE SAFETY LAMP.

Circumstances which led to the formation of a Society for Preventing Accidents in Collieries—Application to Sir Humphrey Davy-Chemical Composition of the inflammable Gas of the Mines-Will not explode in small Tubes, nor from contact with red-hot Iron or Charcoal-First Safe Lantern-Wire-Gauze Cage-Description of the Common Safety LampTestimonials of respect to Sir H. Davy-Opinions of Mr. Buddle and Mr. Fenwick in favour of the Davy"-Petition of the Staffordshire ColliersCircumstances under which Explosions have taken place in connexion with the Davy Lamp.

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IF the appalling circumstances detailed in the preceding Chapter, comprising, as they do, but a very small part of the catalogue of calamities of that class, are calculated to make the least sensitive individual shudder with horror, by how much more must the public, and the pitmen especially, have been laid under obligation by those persons who have devised the means of lessening the number of such occurrences—or rather, invented a method of preventing them altogether. It was impossible, says Dr.

BENEVOLENT EXERTIONS.

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Paris, after alluding to the first catastrophe at Felling Colliery, that an event of such awful magnitude should not have deeply affected every humane person resident in the district. Nothing, in short, could exceed the anxiety which was manifested on the occasion; but most unfortunately there existed an invincible prejudice against every proposition that could be offered, from a general impression of the utter hopelessness of any attempt to discover a remedy. A few philosophic individuals, however, did form themselves into an association for the laudable purpose of inviting the attention of scientific men to the subject, and of obtaining from them any suggestions which might lead to a more secure method of lighting the mines.

To the Rev. Doctor Gray, the late Bishop of Bristol, and who, at the period of the explosions at Felling, was Rector of Bishop-Wearmouth, Dr. Paris acknowledges himself indebted for the several highly interesting communications, by means of which he has "been enabled to present to the scientific world a complete history of those proceedings which have so happily led to a discovery, of which it is not too much to say that it is, at once, the pride of science, the triumph of humanity, and the glory of the age in which we live." It was at a time when all relief was deemed hopeless, that Mr. Wilkinson, a barrister in London, and a gentleman distinguished for the humanity of his disposition, suggested the

* "Life of Sir Humphrey Davy, by J. A. Paris, M.D. &c." From this source, as considered the most circumstantial and authentic, the present Chapter, on the subject of the Safety Lamp, is chiefly drawn. The work is altogether one of delightful interest. There have been several claimants of, and endless discussions upon, the invention of the Safety Lamp, explicit allusion to which will be found in the work here mentioned.

expediency of establishing a Society for the purpose of enquiring whether any, and what, methods of security could be adopted for the prevention of those accidents at that time so frequently occurring in the collieries of Northumberland and Durham. In consequence of this benevolent suggestion, a Society was established at Bishop-Wearmouth, on the 1st of October, 1813. A few days before the first meeting, twenty-seven persons had been killed in a colliery in which Sir Ralph Milbanke had an interest; he was, therefore, called upon at the first meeting to state the particulars of the accident. At that time, as Dr. Gray states, there was such little expectation that any means could be devised to prevent the occurrence of these explosions, that the object of the gentlemen who convened the meeting, however humane in principle, was considered by most of the persons present as chimerical and visionary. The Society, however, amidst many difficulties and considerable discouragement, and a perpetual harass by the offer of impracticable schemes from every quarter, nevertheless persevered in their meetings, and succeeded in establishing a communication and correspondence with other Societies in different parts of the kingdom.

It was in consequence of a private communication from Dr. Gray to his friend Sir Humphrey Davy, that the latter was first led to apply his profound chemical knowledge to an investigation of the nature of the inflammable gas of the coal mines, and also to a discovery of the best means for preventing the occurrence of accidents from this "fire damp," as it was called. In August 1815, Davy visited Newcastle-upon-Tyne, where he had an interview with

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Mr. Buddle, one of the most intelligent coal viewers in the north, and who supplied the philosopher, on his return to London, with various specimens of natural gases collected in the colliery workings, for experiment. Sir Humphrey not only exercised his wonted scientific acumen, in examining the gases, but entered with all his heart into the subject; declaring, in one of his letters, that he "never received so much pleasure from the result of any of his chemical labours; for I trust," adds he, "that the cause of humanity will gain something by it.”

"The fire-damp," says he, in a confidential communication, dated October 30, "I find, by chemical analysis, to be (as it has been always supposed) a hydro-carbonate.* It is a chemical combination of hydrogen gas and carbon, in the proportion of four by weight of hydrogen gas, and 11 of charcoal. I find it will not explode, if mixed with less than six times, or more than fourteen times its volume of at

* The generation, latency, and evolution of this dreadful agent have given rise to much curious enquiry, though hitherto with only very partial success. Mr. Hutton, in a paper containing "Observations on Coal," read before the Geological Society in January 1833, and tending to confirm the importance of those microscopical investigations into the organic structure of this and other fossils, so beautifully carried out by Mr. Witham, ingeniously shews the probability of the gas existing within the coal in so compressed a state as to be liquid. Several circumstances induced Mr. Hutton, while engaged in his microscopic enquiries, to search for a structure in coal capable of containing gas; and he accordingly discovered a system of cells, different from any before noticed, and apparently adapted for that purpose. These supposed gas-cells are found empty, are generally of a circular form, occur in groups, which communicate with each other, and each cavity has in its centre a small pellet of carbonaceous matter. The author establishes a clear distinction between these cells and others which he describes as filled with bituminous matter; for the anthracite of South Wales contains the former, but is quite free from the latter. He also states, on the authority of Mr. F. Foster, that the anthracite of South Wales affords a free disengagement of inflammable gas, when first exposed to the air.-Phil. Mag. Ap. 1833. p. 303.

mospheric air. Air, when rendered impure by the combustion of a candle, but in which the candle will still burn, will not explode the gas from the mines ; and when a lamp or candle is made to burn in a close vessel, having apertures only above and below, an explosive mixture of gas admitted merely enlarges the light, and then gradually extinguishes it without explosion. Again,—the gas mixed in any proportion with common air, I have discovered, will not explode in a small tube, the diameter of which is less than the 4th of an inch, or even a larger tube, if there is a mechanical force urging the gas through the tube. Explosive mixtures of this gas with air require much stronger heat for their explosion than mixtures of common inflammable gas. Red-hot charcoal, made so as not to flame, if blown up by a mixture of the mine gas and common air, does not explode it, but gives light in it: and iron, to cause the explosion of mixtures of this gas with air, must be made white-hot. The discovery of these curious and unexpected properties of the gas, leads to several practical methods of lighting the mines without any danger of explosion." Sir Humphrey then describes four lamps variously constructed, but respectively depending in the main upon the following principles: "First, a certain mixture of azote and carbonic acid prevents the explosion of the fire-damp, and this mixture is necessarily formed in the safe lantern ;— secondly, the fire-damp will not explode in tubes or feeders of a certain small diameter. The ingress into, and egress of air from my lantern, is through such tubes or feeders; and, therefore, when an explosion is artificially made in the safe lantern, it does not communicate to the external air."