Viii THE VIGNETTE. 



it is then lost in the flame of the fire-damp, which now fills the cylinder 

 with a pretty strong light ; and when the foul air constitutes one-third 

 of the atmosphere it is no longer fit for respiration, and this ought to 

 be a signal to the miner to leave that part of the workings. 



Sir Humphry Davy presented his first communication respecting 

 his discovery of the Safety- Lamp to the Royal Society in 1815. This 

 was followed by a series of papers remarkable for their simplicity and 

 clearness, crowned by that read on the llth of January 1816, when the 

 principle of the Safety- Lamp was announced, and Sir Humphry pre- 

 sented to the Society a model made by his own hands, which is to this 

 day preserved in the collection of the Royal Society at Burlington House.' 

 From this interesting memorial the Vignette has been sketched. 



There have been several modifications of the Safety-Lamp, and the 

 merit of the discovery has been claimed by others, among whom was 

 Mr. George Stephenson ; but the question was set at rest forty-one 

 years since by an examination, attested by Sir Joseph Banks, P.R.S., 

 Mr. Brande, Mr. Hatchett, and Dr. Wollaston, and awarding the inde- 

 pendent merit to Davy. 



A more substantial, though not a more honourable, testimony of 

 approval was given by the coal-owners, who subscribed 2500^. to pur- 

 chase a superb service of plate, which was suitably inscribed and pre- 

 sented to Davy.* 



Meanwhile the Report by the Parliamentary Committee " cannot 

 admit that the experiments (made with the Lamp) have any tendency 

 to detract from the character of Sir Humphry Davy, or to disparage 

 the fair value placed by himself upon his invention. The improvements 

 are probably those which longer life and additional facts would have 

 induced him to contemplate as desirable, and of which, had he not been 

 the inventor, he might have become the patron." 



The principle of the invention may be thus summed up. In the 

 Safety-Lamp, the mixture of the fire-damp and atmospheric air within 

 the cage of wire-gauze explodes upon coming in contact with the flame ; 

 but the combustion cannot pass through the wire-gauze, and being there 

 imprisoned, cannot impart to the explosive atmosphere of the mine any 

 of its force. This effect has been erroneously attributed to a cooling 

 influence of the metal. 



Professor Playfair has eloquently described the Safety- Lamp of Davy 

 as a present from philosophy to the arts ; a discovery in no degree the 

 effect of accident or chance, but the result of patient and enlightened 

 research, and strongly exemplifying the great use of an immediate and 

 constant appeal to experiment. After characterising the invention as 

 the shutting-up in a net of the most slender texture a most violent and 

 irresistible force, and a power that in its tremendous effects seems to 

 emulate the lightning and the earthquake, Professor Playfair thus con- 

 cludes : " When to this we add the beneficial consequences, and the 

 saving of the lives of men, and consider that the effects are to remain 

 as long as coal continues to be dug from the bowels of the earth, it may 

 be fairly said that there is hardly in the whole compass of art or science 

 a single invention of which one would rather wish to be the author. . . . 

 This," says Professor Playfair, " is exactly such a case as we should 

 choose to place before Bacon, were he to revisit the earth ; in order to 

 give him, in a small compass, an idea of the advancement which philo- 

 sophy has made since the time when he had pointed out to her the 

 route which she ought to pursue." 



* Weld's History of the Royal Society, vol. ii. p. 188. 



