Joseph Henry's Letter to Jacob Green (February 17, 1834)

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Letter from Joseph Henry, then a professor at Princeton University and later first Secretary of the Smithsonian Institution, to Jacob Green, February 17, 1834. In the letter, Henry describes the electormagnetic motor that he was constructing for Green. The motor was a simple device whose moving part was a straight electromagnet rocking on a horizontal axis. Henry first built his electromagnetic motor c. 1830 and believed his machine was important as the first demonstration of continuous motion produced by magnetic attraction and repulsion.


Princeton University


Historic Images of the Smithsonian


6 pages scanned from the edited transcript of the original version and notes in the Joseph Henry Papers Volume 2, pages 161-166.

Contained within

Reingold, Nathan, et al, eds., The Papers of Joseph Henry, Volume 2, The Princeton Years: November 1832-December 1835 (Washington: Smithsonian Institution, 1975), 161-166

Contact information

Institutional History Division, Smithsonian Archives, 600 Maryland Avenue, SW, Washington, D.C. 20024-2520,


February 17, 1834

Restrictions & Rights

No restrictions


  • Electric apparatus and appliances
  • Secretaries
  • Letters
  • Electromagnets
  • Motors
  • Electromagnetism
  • Electromagnet


  • Document
  • Paper

ID Number

SIA2012-0916 and SIA2012-0917 and SIA2012-0918 and SIA2012-0919 and SIA2012-0920 and SIA2012-0921

Physical description

Number of Images: 6 ; Color: Black and White ; Size: 7w x 10h ; Type of Image: Document ; Medium: Paper

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