A GEORGE III TWO-DAY ARNOLD MARINE CHRONOMETER WITH TRI-METALLIC BALANCE IN OCTAGONAL MAHOGANY BOX

ARNOLD, NO. 119, CIRCA 1797

Details

A GEORGE III TWO-DAY ARNOLD MARINE CHRONOMETER WITH TRI-METALLIC BALANCE IN OCTAGONAL MAHOGANY BOX
Arnold, No. 119, circa 1797
The silvered dial signed ARNOLD. LONDON. No. 119, the hour chapters with Roman numerals within outer minutes chapter with Arabic five minute intermarkers 60-5-10-15 et seque, large subsidiary seconds dial with the cypher J.R.A. interrupting hour and minute numerals (at VI), blued steel hands, Arnold escapement, the top-plate secured to the pillar plate with blued steel screws recessed in turned brass washers, raised barrel bridge signed John Arnold & Son, London, No. 119/209 Invt et Fect., large (50 mm. diam.) cut tri-metallic Arnold Z balance with brass cross-arm, the sectors each with tapped steel outer end carrying threaded heat compensation weights, undersprung blued steel helical balance spring having sixteen coils the bottom coil secured to the top-plate via an adjustable depthing stud, Arnold spring foot detent (replacement), the movement set in mahogany octagonal seating board the top surface with green baize covering, the whole contained in mahogany octagonal box with inset glazed brass and hinged top lid bezel
113 mm. dial diam., box 172 mm. max. width, 104 mm. high

Lot Essay

The inside of the fusee great wheel has scratched therein John Glover, July 24 1797. John Glover was apprenticed to John Arnold and worked at the Arnold factory "Martins" at Chigwell along with Thomas Prest and Richard Jolly. An unusual feature is that, like the previous lot, Arnold No. 18, the fusee winding square is also fitted with a sliding brass cover.
The Z balance rim is also of unusual construction viz the inner surface of each of the two arms forming the complete balance rim is of steel; however the outer surface is brass for about three quarters of its length but the remaining quarter - this at the end where the assembly is screwed to the brass cross-arm - appears to be made of Arnold's non-ferrous compound of platinum and copper.
A similar chronometer No. 78/168 by John Arnold & Sons is in the collection of the Clockmakers Company, Guildhall, London, but it has a bimetallic non-ferrous metal on steel Z balance.

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