Evan-Evans. – This is an automatic-extinguisher lamp; if the lamp should get hot, a solder joint is melted, and a spring forces down a metal cap which closes both the inlet and outlet for air in the bonnet, and so extinguishes the flame.
Wolff's. – This lamp (see Fig. 363) can be lighted without opening; it contains a reel of tape on which explosive composition is placed at intervals of about a quarter of an inch. There is a spring hammer A, operated by the button B, which strikes the explosive composition, the flash from which lights the lamp. The lamp is a spirit-lamp, otherwise it would not light by the flash. The height of the flame is regulated by the screw S, by which the wickpipe is raised or lowered. This invention is ingenious, but it may be doubted whether it is quite safe to use it in a fiery mine; because, if the lamp was extinguished, and subsequently filled with an explosive mixture, the sudden flash of relighting, and the consequent explosion of gas, might force the flame through the gauze. Attached to Wolff’s lamp is a magnetic spring lock. By means of a spring a ratchet is pressed against teeth on the oil-pot, which prevents it from being unscrewed. The application of a powerful magnet, however, will withdraw the ratchet, and permit of the opening of the lamp.