Waltham Grade Sapphire

Description

The nearly 25mm diameter American caliber Waltham Grade Sapphire from the early 20th century is a fairly high-quality windup movement for pocket watches and early wristwatches.

Its jewels, installed in all major bearings, are chaton-mounted, in the visible area, on the train bridges, even secured with screws. Furthermore, the movement is richly decorated with a wave pattern.

The negative winding mechanism, located on the main plate, is of particular interest. When the crown is pressed, a lever, pushed by the tip of the crown stem, directs the Breguet ratchet of the winding mechanism into the winding position; when the pressure is released, the movement returns to the hand-setting position.

The gold-colored gear train is classically constructed, with the ornate steel mainspring barrel, the central minute wheel, the third wheel, the decentral seconds wheel at 6 o’clock, and a very delicate, large escape wheel.

A Swiss pallet fork escapement is used.

The two-leg bimetallic screw balance is, of course, not shock-protected. It operates at 18,000 alternations per hour, and the effective length of its Breguet hairspring can be adjusted using a long regulator arm.

The design of the bent lever pin looks somewhat haphazard. Whether this is intentional or due to damage is unclear.

The dial side is very tidy, as most of the crown mechanism is located on the inside.

Typical of American movements are the two adjusting screws for the pallet fork’s limiting pins, which allow the pallets’ engagement depths to be limited.

Technical data

Usage gallery