Siemens & Halske tantalum filament lamp

Description:

By the late 1890s, carbon filament lamps were no longer the hand-made devices demonstrated by Thomas Edison. He and many others had refined them into mass-produced, reliable products. But the energy efficiency of carbon lamps remained poor, leading researchers—especially in Europe—to seek better filament materials. In 1902 Germans Werner von Bolton and Otto Feuerlien invented a filament made from element number 73, tantalum. Tantalum lamps produced 5 lumens per watt (lpw), much better than the 3.2 lpw of the carbon lamps of that day.

The electrical resistance of tantalum was lower than carbon, though. In order for the total resistance of a tantalum lamp to match the total resistance of a carbon lamp, it had to have a much longer filament. In order to support the longer filament inside a bulb of reasonable size, von Bolton and Feuerlien used a series of hooks attached to the lamp's central glass stem. The filament wound up and down within the bulb. Though the design looked complex, it worked well and was later adopted for the tungsten filaments that replaced tantalum around 1910.

This particular lamp was made by the inventors' employer, Siemens and Halske. Tantalum lamps became the first metal filament lamps offered for sale in the U.S. and in 1909 became the first lamps to carry the trade-name Mazda.

Lamp characteristics: Brass medium-screw base with skirt and porcelain-dome insulator. A tantalum filament with 11 upper and 10 lower support hooks. The support hooks are angled in order to keep tension on the filament, which tended to sag during operation. The stem assembly features soldered twist and crimp connectors, a Siemens-type press seal, and a cotton insulator. Tipped, straight-sided envelope.

Date Made: ca 1907Date Made: ca. 1907

Maker: Siemens & Halske

See more items in: Work and Industry: Electricity, Energy & Power

Exhibition: Lighting a Revolution

Exhibition Location: National Museum of American History

Related Web Publication: http://americanhistory.si.edu/lighting/

Related Publication: Duncan, Robert Kennedy. Some Rare Elements and Their Application, Bright, Jr., Arthur A.. The Electric-Lamp Industry: Technological Change and Economic Development from 1800 to 1947, Lighting A Revolution

Credit Line: from General Electric Company

Data Source: National Museum of American History

Id Number: EM.239147Catalog Number: 239147Accession Number: 46578

Object Name: incandescent lampOther Terms: incandescent lamp; Lighting Devices; Edison; Cage; Metal

Physical Description: tantalum (overall material)glass (overall material)brass (overall material)porcelain (overall material)cotton (overall material)Measurements: overall: 4 3/4 in x 62 3/8 in; 12.065 cm x 158.4325 cm

Guid: http://n2t.net/ark:/65665/ng49ca746a5-3e04-704b-e053-15f76fa0b4fa

Record Id: nmah_704380

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