As a public health precaution due to COVID-19, all Smithsonian museums and the National Zoo are temporarily closed. We are not announcing a reopening date at this time and will provide updates on our website and social media.

Westinghouse tantalum filament "mill" lamp

Westinghouse tantalum filament "mill" lamp

<< >>
Usage conditions apply
Description (Brief)
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.” “Mar-20-94 516,800 APR-16-95 537,493 APR-28-03 726,293 AND OTHERS H.P.5036”. Stamped on base-skirt: “-PA[T Nov. 08 1]904 [Nov. 22] 1904”. “T” inked on stem, “X22 50” on press, “222- [V?]” in base. Label on top is inked: “47D3 1”.
Object Name
light bulb
incandescent lamp
date made
ca 1908
Westinghouse Electric Corporation
Physical Description
glass (overall material)
metal (overall material)
tantalum (overall material)
brass (overall material)
cotton (overall material)
porcelain (overall material)
overall: 7 in x 3 in; 17.78 cm x 7.62 cm
ID Number
accession number
catalog number
See more items in
Work and Industry: Electricity
American Enterprise
Energy & Power
American Enterprise
Exhibition Location
National Museum of American History
Data Source
National Museum of American History
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.

Note: Comment submission on our collection pages is temporarily unavailable. Please check back soon!

If you have a question or require a personal response, please visit our FAQ or contact page.