Joseph Henry's Letter probably to Thomas Cooper (November 26, 1833)

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Letter from Joseph Henry, then a professor at Princeton University and later first Secretary of the Smithsonian Institution, probably to Thomas Cooper, a professor of chemistry at South Carolina College, November 26, 1833. In the letter, Henry describes a magnet he had created, replying to Cooper's request for information. Henry was the first to construct an electromagnet formed by tightly wrapping multiple coils of an insulated conducting wire around an iron bar in 1831. Henry's magnet was capable of supporting 3300 pounds.


  • Cooper, Thomas 1759-1839
  • South Carolina College


Historic Images of the Smithsonian


  • The accompanying PDF contains SIA2012-0906, SIA2012-0907, and SIA2012-0908, which are pages scanned from the edited transcript of the original version and notes in the Joseph Henry Papers Volume 2, pages 130-132.
  • This document is a copy of the original made by Mary Henry.

Contained within

  • Smithsonian Institution Archives, Record Unit 7001, Box 55, Folder: 4 - Joseph Henry Biography Draft (1832 - 1835)
  • Reingold, Nathan, et al, eds., The Papers of Joseph Henry, Volume 2, The Princeton Years: November 1832-December 1835 (Washington: Smithsonian Institution, 1975), 130-132

Contact information

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


November 26, 1833

Restrictions & Rights

No restrictions


  • Electric apparatus and appliances
  • Chemistry
  • Secretaries
  • Letters
  • Inventions
  • Science
  • Electromagnets
  • Magnets
  • Experiments
  • Electromagnet
  • Electromagnetism
  • Science--Experiments


United States


  • Document
  • Paper

ID Number

SIA2012-3612 and SIA2012-3613

Physical description

Number of Images: 2 ; Color: Color ; Size: 7 3/4w x 12 1/2h ; Type of Image: Document ; Medium: Paper

Full Record

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