Mercury vapor lamp, type H1

Description
The type H-1 mercury vapor lamp represented a significant advance in commercial-industrial light sources. Prior to the H-1, mercury lamps contained large amounts of the toxic metal, and most were large and awkward to use. The H-1 featured a small amount of mercury contained in an internal hard-glass "arc-tube" mounted inside the lamp. Compared to previous mercury lamps, the H-1 was a compact and convenient device.
This particular unit is a first generation model from about 1934. A wire grid seen wrapped around the arc-tube helps the unit to start. Later models used a special small electrode for that task. Use of the internal arc-tube allowed the lamp to operate at high internal pressure, resulting in better energy efficiency. While not the first high-pressure mercury vapor lamp, mass production of the H-1 and its ease of use led to its wide adoption. Today's mercury vapor and metal halide lamps can be considered refinements of the H-1.
Lamp characteristics: A brass mogul-screw base with glass insulator. Hard-glass arc-tube with mercury drops visible on the inner wall. Two mandrel and re-coiled tungsten electrodes. Dumet and stranded wire leads connect the base to the electrodes. Starting electrode-grid wrapped around arc-tube and connected to frame. There is no starting resistor in this lamp. Welded connectors. Tipless, T-shape envelope. 400-watt rating.
Mercury vapor lamps are one type of discharge lamp. Other types are fluorescent and neon tubes. They make light by passing an electric current through a gas, and require additional devices called ballasts to operate properly (not seen in the pictures). More information about how discharge lamps operate is on our website Lighting A Revolution.
Object Name
discharge lamp
Date made
ca 1934
date made
ca. 1934
maker
General Electric Company
Physical Description
tungsten (overall material)
mercury (overall material)
glass (overall material)
brass (overall material)
Measurements
overall: 13 in x 2 in; 33.02 cm x 5.08 cm
ID Number
EM*318195
catalog number
318195
accession number
232822
subject
Energy & Power
See more items in
Work and Industry: Electricity
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
from General Electric Large Lamp Department
referenced
Taylor, A. H.; Kerr, G. P.. Character of Light from Mercury Lamps Alone and in Combination with Tungsten Lamps.
Bright, Jr., Arthur A.. The Electric-Lamp Industry: Technological Change and Economic Development from 1800 to 1947
Publication title
Lighting A Revolution
Publication URL
http://americanhistory.si.edu/lighting/

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