Mercury vapor lamp, type H1

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
General Electric Company
Physical Description
tungsten (overall material)
mercury (overall material)
glass (overall material)
brass (overall material)
overall: 13 in x 2 in; 33.02 cm x 5.08 cm
ID Number
catalog number
accession number
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
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

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