What is "lamp jack"

Lamp \Lamp\ (l[a^]mp), n. [F. lampe, L. lampas, -adis, fr. Gr. ?, ?, torch, fr. ? to give light, to shine. Cf. Lampad, Lantern.]

1. A light-producing vessel, device, instrument or apparatus; formerly referring especially to a vessel with a wick used for the combustion of oil or other inflammable liquid, for the purpose of producing artificial light; also, a similar device using a gas as the combustible fuel; now referring mainly to an electric lamp. See sense [3].

2. Figuratively, anything which enlightens intellectually or morally; anything regarded metaphorically a performing the uses of a lamp.

   Thy word is a lamp unto my feet, and a light unto my path.
   --Ps. cxix. 105.

   Ages elapsed ere Homer's lamp appeared.
   --Cowper.

3. (Elec.) A device or mechanism for producing light by electricity, usually having a glass bulb or tube containing the light-emitting element. Most lamps belong to one of two categories, the Incandescent lamp (See under Incandescent) or the fluorescent lamp. However, see also arc lamp, below.

4. A device that emits radiant energy in the form of heat, infrared, or ultraviolet rays; as, a heat lamp.

   [AE]olipile lamp, a hollow ball of copper containing alcohol which is converted into vapor by a lamp beneath, so as to make a powerful blowpipe flame when the vapor is ignited.
   --Weale.

   Arc lamp (Elec.), a form of lamp in which the voltaic arc is used as the source of light.

   D["e]bereiner's lamp, an apparatus for the instantaneous production of a flame by the spontaneous ignition of a jet of hydrogen on being led over platinum sponge; -- named after the German chemist D["o]bereiner, who invented it. Called also philosopher's lamp.

   Flameless lamp, an aphlogistic lamp.

   Lamp burner, the part of a lamp where the wick is exposed and ignited.
   --Knight.

   Lamp fount, a reservoir for oil, in a lamp.

   Lamp jack. See 2d Jack, n., 4 (l) & (n) .

   Lamp shade, a screen, as of paper, glass, or tin, for softening or obstructing the light of a lamp.

   Lamp shell (Zo["o]l.), any brachiopod shell of the genus Terebratula and allied genera. The name refers to the shape, which is like that of an antique lamp. See Terebratula.

   Safety lamp, a miner's lamp in which the flame is surrounded by fine wire gauze, preventing the kindling of dangerous explosive gases; -- called also, from Sir Humphry Davy the inventor, Davy lamp.

   To smell of the lamp, to bear marks of great study and labor, as a literary composition.