Just non-ductile (sintered) tungsten-filament lamp, ca. 1908. First generation tungsten filament lamp. Characteristics: Brass medium-screw base with collar, porcelain-dome insulator. Four single-arch tungsten filaments in series with 4 upper, 6 lower supports. Welded or paste connectors, Siemans seal. Glass stem is mounted on two shock-absorbing springs (one set in the press, the other attached to a glass rod that is set in the exhaust tip). Tipped, straight-sided envelope with taper at neck. Lamp developed by Dr. Alexander Just and Franz Hanaman in Vienna in 1902. Mazda A type. Printed on lamp: “Just Tungsten Lamp Pats. Pending”. Written on lamp: “20246a.1628”. Something else is written at base, near neutral lead-weld. [See Bright, Electric Lamp Industry, pp. 184-94.]
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