One of Monticello's most memorable features is the Great Clock, designed by Jefferson, built by Peter Spruck in 1792, and fully functional today. The clock, with both an interior and exterior face, dictated the schedule of the entire plantation, inside the building and out. On the outside wall, the clock has only an hour hand, which Jefferson believed was accurate enough for outdoor laborers. The clock is attached to a Chinese gong that chimes the hour. In the eighteenth century, the gong rang loudly enough for field slaves to hear it three miles away.
The inside face of the clock reveals much greater precision by offering not only hour and minute hands, but also a smaller dial for a second hand. The seven-day clock is driven by two sets of cannonball-like weights, which hang on both sides of the front doors. On Sundays the clock is wound with the help of a folding ladder, and the weights are raised to the ceiling. Throughout the week, the top ball on the right-hand set of weights reveals the day and even the approximate hour as it falls past markers on the wall, with Sunday at the top and Saturday at the bottom. In the picture shown below (which can be enlarged), the time is mid-day on Tuesday.
There is a hitch, however; Jefferson designed the clock for a home in Philadelphia, and upon the arrival of weights for the its installation at Monticello, it was discovered that the height of the Entrance Hall was shorter than the length of the ropes. Jefferson's solution? To allow the weights "to descend naked till they get to the floor where they may enter a square hole and go [on?] to the cellar floor. . . ." The holes were cut, the weights were hung, and the marker for Saturday may be found on the basement level of the house.
For further information, please see The Worlds of Thomas Jefferson at Monticello by Susan R. Stein.
The "Grass-Green" Floor
In 1805, after sitting for a portrait done by Gilbert Stuart, Jefferson wrote home to the workman James Dinsmore, explaining his latest idea for the Entrance Hall:
After writing to you yesterday, I was at the painting room of Mr. Stewart (the celebrated portrait painter) who had first suggested to me the painting a floor green, which he had himself tried with fine effect. He observed that care should be taken to hit the true grass-green, and as he had his pallet and colours in his hand, I asked him to give me a specimen of the colour, which he instantly mixed up to his mind, and I spread it with a knife on the enclosed paper. Be so good there fore as to give it to Mr. Barry as the model of the colour I wish to have the hall floor painted of. . . . Accept my good wishes.
P.S. The floor should be painted the instant you have it ready, and all other work should give way to getting that ready.
Ironically, the floor was not painted for another two years!