Most incandescent lamps were designed for general use in homes and businesses. However, some required special features for use in particular locations. Westinghouse engineers designed this so-called mill lamp for use in factories and other areas subject to high levels of vibration. An intricate internal support structure absorbed vibrations and kept the filament intact for the life of the lamp. Lamps of this type were later sold as rough-service lamps. The filament itself is made from the element tantalum. Invented in 1902, tantalum filament lamps sold in the U.S. until about 1910 when tungsten lamps were introduced.

Westinghouse tantalum filament "mill" lamp, circa 1908. Brass medium-screw base with skirt, two glass insulators. Two drawn tantalum filaments (in series) with 12 upper, 22 center, and 10 lower copper support hooks. Crimp connectors, Siemens seal, cotton insulator. Tipped straight-sided envelope. Westinghouse label on lamp reads: “Westinghouse Tantalum [inked 223] V 50 W, patent label in stem: “The manufacturer of this lamp is licensed under patent noted on other side.”

(Information was gathered at the Smithsonian national museum of American history)

Incredible lot of 2 antique Westinghouse 50w tantalum light bulbs. The little label housed within the bulb itself gives multiple paten dates starting with Jan/2/1895 and ending with April 24th 1906. Both bulbs have been tested and work very well, very bright! the bulbs still have multiple paper labels still attached. These bulbs were take out of, and made for an antique mirror scope. The mirror scope is available in our store. Both bulbs appear to be hand blown and have pontil tips on each. Minor bubbles in glass from the manufacturing process’s. See photos for more details any questions please feel free to contact us.