Tall case clock pendulum
Date1760-1770
Artist/Maker
John Berridge
MediumBrass and steel.
DimensionsOL: 45"; W of bob: 6"
Credit LineMuseum Purchase
Object number1954-931,C
DescriptionBrass and steel gridiron-type pendulum to compensate for thermal expansion with cast-iron bob of lunette shape measuring 6” H x 6” W. The pendulum contains a mechanism for extremely precise length adjustment in order to achieve timekeeping accuracy. The overall length of the pendulum is 45”.Label TextThis clock has a temperature compensating pendulum with precision adjustment. The center steel pendulum shaft is flanked by two brass rods with a compensation mechanism between the brass rods and the bob. The difference between the thermal expansion of the brass and steel combined with the mechanism adjusts the position of the bob and keeps it at the same distance from the pivot point at all times, thus allowing the swing of the pendulum to remain consistent and the clock to remain accurate despite changes in temperature. Clockmaker John Berridge is documented as having made a clock with a compensated pendulum for a Mr. Fotheringham of Holbeach, England in 1738.
