It is an oil-burning miner's safety lamp invented
by Sir Humphry Davy in 1816 when investigating firedamp
(methane) explosions in coal mines.
The lamp has a
metal gauze surrounding the flame, which cools the
hot gases by conduction and prevents ignition of gas
outside the gauze. If firedamp is present it burns
within the gauze cage and lamps of this type are still
used for testing for gas.