Incandescent lamp with ductile tungsten filament

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.
Object Name
incandescent lamp
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)
overall: 18 cm x 7 cm; 7 1/16 in x 2 3/4 in
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 Princeton University, Dept. of Electrical Engineering, thru Dean Howard Menand
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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