Name of a variety of lamps for safety in coal-mines against "fire-damp," a highly explosive mixture of natural gas apt to accumulate in them; the best known being the "Davey Lamp," invented by Sir Humphrey Davy; the "Geordie," invented by George Stephenson, both of which, however, have been superseded by the Gray, Muesler, Marsant, and other lamps; all are constructed on the principle discovered by Davy and Stephenson, that a flame enveloped in wire gauze of a certain fineness does not ignite "fire-damp."