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The Great Clock

The Great Clock View Interactive Version ]

Monticello's Great Clock is mounted in the Entrance Hall and has a second face on the east front of the house. Jefferson’s instructions for the clock’s construction explain his intent for the exterior face, which has only an hour hand:

a toothed wheel of 2.I. [inches] on the back end of the axis of the hour hand…may turn an hour hand on the reverse face of the wall on a wooden hour plate of 12I. radius. There need be no minute hand, as the hour figures will be 6.I apart. But the interspace should be divided into [qu]artersand 5. minute marks.1

The Entrance Hall face indicates the hours and minutes on a larger dial, and the seconds on a smaller one. The clock is powered by two sets of cannon-ball-like weights (eighteen pounds each), which drive its ticking and the striking of a gong on the roof. The weights are strung on ropes and descend in the corners of the room on either side of the clock, through holes in the floor to the cellar below. Jefferson placed labels next to the path of the ticking (or running) weights to indicate the days of the week. The clock was wound every Sunday with a crank-like key, and a folding ladder was made in the Monticello joinery for that task.

Jefferson began planning the Great Clock in 1792, while in Philadelphia. He wrote to Henry Remsen, chief clerk of the foreign desk of the department of state, to inquire about Chinese gongs for the clock:

The chinese have a thing made of a kind of bell metal, which they call a Gong, and is used as a bell at the gates of large houses, etc…I wish for one to serve as the bell to a clock, which might be heard all over my farm.2

Benjamin Franklin’s use of a gong in place of a bell, may have inspired Jefferson.3

By the beginning of 1793, the clock had been completed to Jefferson’s specifications in Philadelphia by Peter Spurck, an apprentice to Robert Leslie, whose workmanship Jefferson found less than satisfactory. Jefferson wrote to Leslie in December 1793:

My great clock could not be made to go by Spruck. I ascribe it to the bungling manner in which he had made it. I was obliged to let him make the striking movement anew on the common plan, after which it went pretty well…

The clock was probably installed in Jefferson’s Philadelphia house at Gray’s Ferry before it was transported to Virginia.4 It was brought to Monticello when Jefferson returned there in 1794, and he soon solicited clockworkers to undertake its repair. At this same time he finally procured a gong for use with the clock.5

It was not until 1804, while president, that Jefferson ordered the weights for the clock from the Foxhall Foundry in Washington, D.C.6 In January of that year, Jefferson was first confronted with the fact that the length of the descent of the clock weights, which he planned to have enclosed in a box, was greater than the height of the Entrance Hall. In a letter to James Dinsmore Jefferson arrived at the notable solution:

I do not approve of cutting the wall, not even the cellar wall to make a space for the descent of the clock weights, but would have them advanced into the room so as to descend clear even of the cellar wall. Should the box in this case encroach too much on the window we may avoid the eye sore by leaving them naked till they get to the floor where they may enter a square hole and go [on?] to the cellar floor…7

The Great Clock has never been removed from Monticello since its installation in 1804-5.

Artist/MakerPeter Spurck, exterior designed by Thomas Jefferson
Object TypeClocks and Maps
MaterialsWood, wrought iron, cast iron, brass
Dimensions45 3/8 x 29 1/2 x 16 1/4 in.
LocationEntrance Hall


  1. Thomas Jefferson, "the great clock, " undated manuscript, Massachusetts Historical Society.
  2. Thomas Jefferson to Henry Remsen, Jr., 13 November 1792, American Memory Project - The Thomas Jefferson Papers.
  3. Franklin's gong is mentioned in Henry Remsen to Thomas Jefferson, 19 November 1792, American Memory Project - The Thomas Jefferson Papers, after Jefferson's order, however Jefferson was likely already aware that Franklin owned a gong.
  4. Thomas Jefferson to Robert Leslie, 12 December, 1793, University of Virginia.
  5. James A. Bear, Jr., Jefferson's Memorandum Books, 27 April 1793; Silvio Bedini, "Thomas Jefferson Clock Designer," Proceedings of the American Philosophical Society 108, (June 1964): 165-170.
  6. Thomas Jefferson to Archibald Stuart, 23 May, 1795, University of Virginia.
  7. Jefferson gave a second gong to his good friend Archibald Stuart in Augusta County, Virginia. James A. Bear, Jr., Jefferson's Memorandum Books, 30 October 1794, 11 December 1795; Thomas Jefferson to Archibald Stuart, 6 January 1797 Virginia Historical Society.
  8. James A. Bear, Jr., Jefferson's Memorandum Books, 9 July 1804.
  9. Thomas Jefferson to James Dinsmore, 28 January 1804, transcription from Sotheby's catalogue, Printed and Manuscript Americana, 26 January 1983.

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