Made by David Rittenhouse. Pine case without embellishment, 83 ½" high, 13 ¼" wide at waist. The dial is 10 ⅝" diameter, probably of cold silvered brass. Unmarked. Received about 1810.
Heavy brass plates with a pillar at each of the four corners contain the deadbeat escapement and going train of two manytoothed wheels. The motion work is between the dial and front plate. A small gear on the #2 gear arbor drives a large gear carrying the minute hand. The hour hand is driven by the latter gear through a compound idler gear and pinion. The second hand is mounted on the escape wheel arbor. The pendulum vibrates seconds and is mercury compensated. It is in two pieces connected by a yoke, and suspended by two springs. A thermometer is mounted on the back of the case.
This clock was built by Rittenhouse for his observatory at Norriton, and used in the observations of the transit of Venus in 1769. It is described in Barton's Memoir of Rittenhouse ( 1817) as "an excellent timepiece, having for its pendulum rod a flat steel bar, with a bob weighing about 12 pounds, and vibrating in a small arc. This went eight days, did not stop when wound up, beat dead seconds, and was kept in motion by a weight of 5 pounds."25
In 1810 the executors of Rittenhouse's estate offered to transfer the clock and "instruments" (see 58-24, fig. 2) to the Society in return for the observatory building and site. This was accepted. The exact date of the transfer of the instruments is not known.
Made by Edward Duffield. Mahogany case. Bell-top hood with three beet-shaped wooden finials, the base of the center one____________________