Incandescent lamp with ductile tungsten filament
date: label: Date made
content: ca 1911
label: date made
content: ca. 1911
label: date made
content: 1911
notes: label: Description
content: In 1904 several European inventors almost simultaneously developed lamp filaments made with the metal tungsten. These gave better energy efficiency than older carbon lamp filaments. However, tungsten proved a difficult metal to work. A pressing technique called "sintering" was used, but the resulting filaments were brittle and could not be bent once formed. Called "non-ductile" filaments, they required a complex mounting structure with several filaments placed one after the other in the electrical circuit.
label: Description
content: William Coolidge, working at the General Electric Research Laboratory in Schenectady, New York, began investigating how tungsten lamps might be improved by making a bendable or "ductile" wire. In 1909 he found an answer. By putting an ingot of sintered tungsten through a series of hot swagings and drawings through successively smaller dies, bendable wire of many diameters could be made. GE began selling Coolidge's lamp under the trade name "Mazda" beginning in 1910. Since it was the second generation of tungsten filament lamps, it became known as the Mazda B.
label: Description
content: Mazda B lamps sold well throughout the 1910s and 1920s. The heavy copper hooks supporting the filament in this particular example tell us this is an early Mazda B lamp. It dates from around 1911.
label: Description
content: Lamp characteristics: Brass medium-screw base with skirt and two glass insulators. Drawn tungsten filament with 6 upper and 5 lower heavy-copper support hooks. The black material seen on the lower hooks is called Needham's getter. It bonds chemically with oxygen and helps keep the filament from burning up. The stem assembly features crimp-style connectors, offset leads, a Siemens-type press seal, and a cotton insulator. Tipped, straight-sided envelope with taper at neck.
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 Princeton University, Dept. of Electrical Engineering, thru Dean Howard Menand
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.318637
label: catalog number
content: 318637
label: accession number
content: 232729
objectType: label: Object Name
content: incandescent lamp
label: Other Terms
content: incandescent lamp; Lighting Devices; Edison; Cage; Metal
physicalDescription: label: Physical Description
content: tungsten (overall material)
label: Physical Description
content: brass (overall material)
label: Physical Description
content: glass (overall material)
label: Physical Description
content: copper (overall material)
label: Physical Description
content: cotton (overall material)
label: Measurements
content: overall: 7 1/16 in x 2 3/4 in; 17.93875 cm x 6.985 cm