Concave Mirror

Artist/Maker: William Jones (1763-1831) and Samuel Jones

Created: c. 1807

Origin/Purchase: London

Materials: glass, with walnut frame

Dimensions: D: 30.5 (12 in.); 33.7 (13 1/4 in.) with frame

Location: Cabinet

Provenance: Thomas Jefferson; by purchase to George Toole at the Dispersal Sale in 1827; by descent to Mrs. John Toole; by purchase to Henry Polkinhorn; by gift to William Wilson Corcoran; by purchase to an unidentified Washington dealer; by purchase to Mr. and Mrs. Parry Borgstrom; by gift of Ruth D. Borgstrom to the Thomas Jefferson Foundation in 1961

Accession Number: 1961-15

Historical Notes: In 1806 Jefferson ordered from the London firm W. & S. Jones "a 12. Inch Concave glass mirror in a plain black frame" costing £2-5.[1] He had acquired a larger concave mirror in a more elaborate frame while living in France in the 1780s, for which this was probably a replacement.[2]

Jefferson intended using his concave mirrors, as well as the condensing lenses and scioptric ball he bought in London in 1786, with his microscopes.[3] As he wrote in 1822, "in microscopic observations, the enlargement of the angle of vision may be more indulged, because auxiliary light may be concentrated on the object by concave mirrors."[4] The reflecting mirror of a compound microscope would be placed at the focal point of the mirrors.

When a viewer stands outside the focal point of a concave mirror, his image is reflected upside down. This optical phenomenon may account for the mirror's location in the Entrance Hall in an inventory prepared shortly after Jefferson's death.[5] It might have become a source of family entertainment in Jefferson's last years, when he had abandoned more complex scientific experiments.

- Text from Stein, Worlds, 359

References

  1. ^ Jefferson to William Jones, October 25, 1806, Thomas Jefferson Papers, Library of Congress. Transcription available at Founders Online.
  2. ^ A concave mirror is included on Jefferson's list of "Mathematical Apparatus." Manuscript available online at 1783 Catalog of Books, [circa 1775-1812], page 244, by Thomas Jefferson [electronic edition], Thomas Jefferson Papers: An Electronic Archive (Boston: Massachusetts Historical Society, 2003). See also Silvio A. Bedini, Thomas Jefferson: Statesman of Science (New York: Macmillan 1990), 501.
  3. ^ For the purchase of two double convex lenses and a scioptric ball, see P. & J. Dollond Invoice, April 3, 1786, The Thomas Jefferson PapersSpecial Collections, University of Virginia Library.
  4. ^ Jefferson to Thomas Skidmore, August 29, 1822, Thomas Jefferson Papers, Library of Congress. Transcription available at Founders Online.
  5. ^ [Martha Jefferson Randolph?], Monticello: furniture inventory, page 1 of 8, [after 1826], N147jj [electronic edition], Thomas Jefferson Papers: An Electronic Archive (Boston: Massachusetts Historical Society, 2003).