Thomson DC Generator
date: label: Date made
content: 1886
label: patent date
content: 1886-01-05
name: label: associated person
content: Thomson, Elihu
label: associated company
content: Thomson-Houston Electric Company
label: maker
content: Thomson, Elihu
notes: label: Description
content: This model of a direct-current generator was designed by Elihu Thomson to produce a constant voltage. It could also be used as a motor that would maintain a constant speed. It came to the Smithsonian from the U. S. Patent Office, representing patent number 333,573, issued to Thomson on January 5, 1886. The patent itself indicates that no model was submitted (which is not surprising since by that time models were not required), and this example was probably given to the Patent Office at a slightly later date for display purposes.
label: Description
content: Thomson and Edwin Houston were school teachers in Philadelphia in the 1870s when they formed a partnership (the Thomson-Houston Company) to enter the new and competitive arc-lighting field. They produced a number of successful generators, motors, meters, and lighting devices. Most of their system employed alternating current, which was as good as direct current for lighting. With the development of the transformer in the mid-1880s, AC systems assumed added importance because electricity generated at a low voltage could now be converted to high voltage for more efficient transmission and then converted back to safer low voltage for use by consumers. But electro-chemical applications (like plating) required DC generators, and, until the invention of a practical AC motor by Nikola Tesla at the end of the 1880s, street railways depended on DC.
label: Description
content: Thomson-Houston merged with Edison's company in 1892 to form General Electric.
label: Description
content: See US Patent 333573, "Dynamo Electric Machine," issued 5 January 1886 to Elihu Thomson. Claim: "A design with spherical armature and round-type frame to obtain a dynamo-electric machine capable of furnishing a constant potential; or an electric motor capable of maintaining a constant speed." No extant maker's markings. This machine has a revolving circular armature with pulley wheel on one end of shaft and adjustable brushes at the other. Field magnets are supported inside the frame.
label: Location
content: Currently not on view
place: label: Place Made
content: United States: Pennsylvania, Philadelphia
setName: label: See more items in
content: Work and Industry: Electricity
label: See more items in
content: Energy & Power
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.252663
label: catalog number
content: 252663
label: patent number
content: 333573
label: accession number
content: 49064
objectType: label: Object Name
content: motor
label: Object Name
content: electric motor
label: Object Type
content: Patent Model
label: Other Terms
content: motor; Motors and Generators
physicalDescription: label: Measurements
content: overall: 6 in x 10 1/2 in x 10 3/4 in; 15.24 cm x 26.67 cm x 27.305 cm