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Tall case clock

1760-1770
Origin: England, Boston
OH: 82"; OW: 20 1/2"; OD: 10"
Mahogany, oak, and glass; brass, silvered brass, steel, and iron.
Museum Purchase
Acc. No. 1954-931,A&B
Appearance:
Case:
Arched bonnet with square plinths for finials at front corners and chamfered front corners; arched, molded door to trunk, stepped base molding.

Dial:
Round 12” diameter silvered brass dial with large engraved Arabic seconds dial and single seconds hand; small Arabic minute dial in top portion of dial; lunette aperture for Arabic hours above single winding hole and maker's name "John Berridge/ Boston" in cursive.

Movement description:
Eight-day weight driven laboratory regulator timepiece to measure elapsed time in seconds, minutes, and hours. Movement measures 11 ¼” H x 4 1/8” W. Plate thickness is 0.125”. Distance between plates is 2 3/8”. Precision movement for high accuracy time measurement contains a dead-beat escapement, bolt-and-shutter maintaining power so timepiece does not stop during winding; six plate pillars (vs usual 4) for maximum movement rigidity; all gear pivots protruding through plates are covered with brass covers to prevent oil from contacting dust which will wear and slow down timekeeping; movement bolted to seat board via bolts from underneath center into right angle brass brackets fastened to back plate; center, third and escape pinions of eight leaves (not six) for smoother operation. Plate pillars are secured to front plate via sliding latches not the usual pins. All gears in movement have four spokes except for escape wheel which has six.

Weight pulley is standard cast-brass pulleys with riveted stirrup. Brass 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”. The weight is cast iron with a cast in loop for the pulley hook. The weight is 9” long. It is 3” diameter at the top and 2.6” diameter at the bottom.

No strike train, winding drum, or bell.
Mark(s):"John Berridge/ Boston" in cursive in center of dial under hours lunette.