From the collection of the late GIL MARGOLIS

A FRODSHAM TWO-DAY MARINE CHRONOMETER WITH DOUBLE COMPOUND MICROMETER EQUATION BALANCE

CHARLES FRODSHAM, NO. 0025, CIRCA 1890

細節

A FRODSHAM TWO-DAY MARINE CHRONOMETER WITH DOUBLE COMPOUND MICROMETER EQUATION BALANCE
Charles Frodsham, No. 0025, circa 1890
The silvered dial signed and numbered CHARLES FRODSHAM 84 STRAND. LONDON No. 0025, Roman hour numerals within outer minute chapter with Arabic five-minute intermarkers, subsidiary seconds and up-and-down dials, blued steel hands, reversed fusee, Earnshaw escapement, modified double compound micrometric equation balance comprising outer uncut steel flat rim and cross arm with raised mean time screws and above the plane of the balance rim and at right angles to the cross arm an auxiliary of 'Z' shaped construction comprising three parallel bimetallic brass-on-steel laminations with vertically mounted cylindrical brass heat compensation screws, spring foot detent with jewelled locking stone, brass bowl, gimballed in three-tier coromandel wood box with velvet lined top lid, quarter round brass edging and double stringing, with inset mother-of-pearl disc, flush recessed carrying handles
95 mm. dial diam., 185 mm. sq. box

拍品專文

This version of Frodsham's double compound micrometric balance is of complex construction and operation. In its earlier form it was exhibited in the second International Exhibition held at South Kensington, London in 1862. See Vaudry Mercer, The Frodshams, 1981, plates 62 and 63, page 405. On page 116 it is stated that "The double compound Micrometric Equartion balance", was to form the basic principle for the later "Frodsham balance" which was employed in his finest marine chronometers and carriage clocks."