It may easily be imagined that many efforts have been made, and many contrivances suggested, to disarm the fire-damp of its terrors; but Sir Humphry Davy’s safety-lamp was the first invention which successfully coped with it. The power of the safety-lamp lies in the _non- communication of explosions through small apertures_, and the discovery of this natural law, as well as its practical application, is one of the greatest exploits of Sir Humphry Davy. A cylinder an inch and a half in diameter and seven inches long, formed of wire gauze, with 784 apertures to the square inch, surrounds the light of the lamp. When the miner, armed with this apparatus, enters an atmosphere tainted with fire-damp, a light blue flame fills the cylinder; but, as if chained by some magic power, it is unable to transgress its bounds; and as in our Zoological Gardens we quietly view the beasts of the forest behind their iron grating, so the miner looks calmly upon his powerless foe. Unfortunately, the negligence or the obstinate and blind perversity of the miner too often renders even this splendid invention ineffectual. The safety-lamp requires to be kept in perfect order, and unless certain precautions are taken while using it, it loses its protecting power. Thus, although perfectly secure when at rest, it seems certain that the rapid motion communicated by the swing of the arm during a hurried transit through the mine has in many cases produced an explosion. Blowing out the lamp is likewise attended with danger, as the flame is then easily driven through the gauze, and, like a tiger escaping from his den, may spread terror and havoc around; but the chief cause of accidents consists in the small quantity of light diffused by the safety-lamp, and the consequent dislike acquired by the miners to its use. Though in all well-regulated coal-pits one or several workmen are exclusively employed in keeping the lamps in the most perfect order, though they are handed to the miners burning and well closed, and fines are imposed upon any attempt to remove the gauze, yet the best regulations cannot possibly exclude the chance of accident resulting from the almost inconceivable carelessness of men whose daily tasks lead them into imminent danger. Thus it is a melancholy but unquestionable fact that the number of accidents from fire-damp since the introduction of the Davy lamp has been many more in a given number of years than before that invention. This has, no doubt, partly arisen from the larger number of persons employed on the whole; but it is to be feared that it has chiefly happened from dangerous portions of a mine being taken into work which without the _Davy_ could not have been attempted, and partly also from the extreme carelessness of the workmen in removing the wire gauze.[40] Footnote 40: