Low pressure sodium lamp, type Na-10
date: label: date made
content: ca. 1940
label: Date made
content: ca 1940
name: label: Associated Name
content: Sero, Charles M.
label: maker
content: General Electric Vapor Lamp Company
notes: label: Description
content: As knowledge of materials and experience making electric lamps grew in the early 20th century, more efficient light sources began to reach the market. In 1932 a collaboration of General Electric Company of England (GEC), Philips in the Netherlands, and Osram in Germany introduced a discharge lamp that used low-pressure sodium vapor. The key to a workable sodium lamp lay in a special glass (called borate glass) that could withstand the very corrosive nature of sodium. Arthur Compton in the U.S. described such a glass in 1926. But it took five more years to learn how to actually produce it so that a lamp could be made.
label: Description
content: Discharge lamps make light by passing an electrical current through a gas, in this case sodium vapor. The current energizes the gas which then emits light. In this lamp, the sodium is contained by the bulb, which is lined with the borate glass. The lamp in turn is mounted inside a larger, double-walled glass jacket (part of the light fixture, not shown) to keep the temperature around the lamp stable during operation. Sodium light is a stark yellow suitable only for use in applications like street lighting, but the energy efficiency is very high. Early models gave 40 lumens per watt (lpw), a figure that reached about 100 lpw by 1960. Today's low-pressure sodium lamps give close to 200 lpw, the most energy efficient light source commercially available.
label: Description
content: This lamp was made for street-lighting use by (U.S.) General Electric around 1940.
label: Description
content: Lamp characteristics: Plastic, four-post base. Re-coiled tungsten electrodes mounted inside metal shields. The small brown cylinder mounted near the stem press is a starting resistance. Six asbestos insulator rings mount on the lamp's neck and are secured by the brass collar. (The rings have been removed and stored while the lamp is on display and are not in this picture.) Tipless, T-shaped envelope with about 70% of the inner wall coated by condensed sodium.
setName: label: See more items in
content: Work and Industry: Electricity
label: See more items in
content: Energy & Power
label: Exhibition
content: Lighting a Revolution
label: Exhibition Location
content: National Museum of American History
publisher: label: Related Publication
content: Bright, Jr., Arthur A.. The Electric-Lamp Industry: Technological Change and Economic Development from 1800 to 1947
label: Related Publication
content: Lighting A Revolution exhibition website
label: Related Web Publication
content: http://americanhistory.si.edu/lighting/
creditLine: label: Credit Line
content: from the Mt. Vernon Museum of Incandescent Lighting, thru Hugh F. Hicks
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1997.0387.14
label: accession number
content: 1997.0387
label: catalog number
content: 1997.0387.14
objectType: label: Object Name
content: discharge lamp
physicalDescription: label: Physical Description
content: plastic (overall material)
label: Physical Description
content: glass (overall material)
label: Physical Description
content: sodium (overall material)
label: Physical Description
content: metal (overall material)
label: Measurements
content: overall: 13 in x 3 in; 33.02 cm x 7.62 cm