A CONTINENTAL ONE-DAY MARINE CHRONOMETER

細節

A CONTINENTAL ONE-DAY MARINE CHRONOMETER
Anonymous, No. 123, circa 1875

The frosted silver dial of regulator format with subsidiary hours dial (at XII), Roman hour numerals and arrow-head blued steel hour hand, subsidiary seconds dial (at VI), outer minute chapter with Arabic five minute intermarkers and lance shaped blued steel hand, satin gilt finish pinned full-plate movement, balance bridge with diamond endstone, the balance with three prism-shaped polished steel arms, each separately attached to the three bimetallic sectors forming the balance rim, each sector with milled edge on its underside and carrying laterally adjustable heat compensation weights and mean time screws, grey steel helical balance spring with the top coil pinned to an elongated resilient stud, fifteen tooth escape wheel, pivoted detent, in brass drum-shaped dust cover with underspringing contained in gimballed brass bowl with bolt format locking arm, plain three-tier mahogany box (later top lid) the middle section with bone ivory plaque (unsigned)
73 mm. dial diam., 160 mm. sq. box

拍品專文

The pivoted detent is of unusual format and is probably of experimental design. It comprises an arbor carrying at the top a brass table-roller mounted above which and secured to it is a polished steel locking pallet: approximately 4 mm. beneath the roller and mounted on the same arbor is the steel detent blade and passing spring which is moved to-and-fro to effect locking and unlocking by the steel discharging roller which ipso facto is positioned on the balance staff approximately 4 mm. beneath the steel impulse roller.

Apart from the group 123 punched on the dial side of the dial plate no other identification marks have been found. There is evidence that at one time a form of start/stop balance brake was fitted.