A most important George III mahogany longcase regulator,
signed “Josiah Emery, Charing Cross. London,” circa 1785
79 in. [201 cm] H
22 in. [56 cm] W
10 ½ in. [27 cm] D
A technically innovative regulator whose gridiron pendulum was probably supplied by his colleague John Arnold. The highly finished dead beat escapement employs the pallet geometry introduced by A.-L. Breguet for his first lever watches. The V-shaped anchor has curved impulse pallet faces with concave entrance and convex exit surfaces intended to equalize impulse.
The case rests on a paneled rectangular plinth below a tapered trunk with molded door shaped to conform with the shallow arch of the hood. The silvered dial, signed in the arch, has a minute ring enclosing an hour aperture and subsidiary seconds ring. The hour wheel is engraved on both surfaces: 1 - 24 on the front and twice 1 - 12 on the reverse. The seconds and minute hands are blued steel with the latter having a heart shaped tip. The dial feet are secured to the front plate by three screws each. The interior of the case is fitted with sliding glazed panels forming a partition to enclose the pendulum.
The six pillar movement has a dead beat escapement, Harrison's maintaining power, a fully end capped, high count train with jewels to the escape wheel and anchor arbors.. The finely cut wheels have six crossings. The borders of the plates have been cut with grooves to hold dust shutters.
A five-rod zinc and steel gridiron pendulum, is suspended from a substantial back cock on the movement. The beat adjustment is above the suspension. Just below its suspension, the pendulum rod is fitted with an open work, lozenge-form, brass and steel brace to engage the crutch. The gridiron is of the form introduced by John Arnold, consisting of two zinc and three steel rods. The large brass-clad bob is pierced with rectangular openings forming a bridge acting as the point of suspension. In this configuration, the bob's center of gravity rests on a screw threaded into the lowest cross piece of the pendulum. The screw may be turned for adjustment by means of a pin inserted into small holes around the edge of a calibrated rating scale below the cross piece. The screw also carries a spherical fine adjustment weight below the bob and terminates with an index to the silvered beat scale.
Because of its unusual pallet geometry, the clock may have been somewhat experimental.
The influence of Emery on the development of the lever is widely acknowledged and it is interesting that these unusual pallets should be found on a regulator by Emery. Curved impulse pallet faces are otherwise encountered on a few of the early lever watches by A.-L. Breguet. In addition, his earliest locking faces are concentric with the axis of the lever [i.e. anchor], as in a dead beat escapement.
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