Incandescent lamp with ductile tungsten filament

Description
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.
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.
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.
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.
Date made
ca 1911
date made
ca. 1911
Physical Description
tungsten (overall material)
brass (overall material)
glass (overall material)
copper (overall material)
cotton (overall material)
Measurements
overall: 18 cm x 7 cm; 7 1/16 in x 2 3/4 in
ID Number
EM.318637
catalog number
318637
accession number
232729
Credit Line
from Princeton University, Dept. of Electrical Engineering, thru Dean Howard Menand
See more items in
Work and Industry: Electricity
Energy & Power
Data Source
National Museum of American History, Kenneth E. Behring Center

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