Clock 4

Deck Clock 13496

7.5 x 7.5 x 7.75 inches

Vintage, brass, gimbal­mounted, 2–day, marine chronometer in a three tier, brass bound mahogany carrying case, Chronometer Serial No. 13496, made by the firm of Thomas Mercer, Maker to the Admiralty, (made by Thomas Mercer Jr. (1876­1935) and his brother Frank Mercer(1882­1970), Eywood Road, St. Albans, England, circa 1925–1930.

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Case: 7.5" x 7.75" x 7.5", Three­tiered, solid mahogany, brass­ bound carrying case to hold this gimbaled marine chronometer. The case, with three lids should have the identical serial number of the chronometer watch it carries, "13496", has a key lock escutcheon and is brass bound at all three tiers and has five­knuckle grass hinges. The upper lid opens to allow reading the chronometer watch through a glass cover. The second lid was opened for winding and setting procedures. Inside the case there is an open face, chronometer watch, sitting within a brass bowl and mounted in chronometer type brass gimbals. The brass gimbal ring is pivoted from the sides of the box at two points 180 degrees apart. In addition, the brass case of the watch movement was also pivoted at two points 180 degrees apart and 90 degrees away from the gimbal ring mounting. This allowed the box to be tilted in any direction with the watch remaining level. The gimbal mount has a safety lock used to lock the watch into a position for transport.

Dial: Silvered round dial with enameled black Roman hours, closed minute ring to the outside, subsidiary continuous seconds Arabic dial @6 enclosing the serial number, 13496, and a power reserve indicator under the twelfth hour with 56 hours of reserve power marked, 'up/down'. There are blued­ steel Continental type Spade hands. The dial mentions various awards such as the Kew timing awards in England as well as those in Neuchatel, Switzerland. The dial is marked, "Thomas Mercer, Maker to the Admiralty, Eywood Road, St. Albans" (This location was where the company had offices as of 1911 ­ Thomas Mercer Sr. had died in 1900). The base of the dial is marked in red, 'Auxiliary Compensation' (see movement).

Movement: This is a two–tier solid round damascene or spotted brass plate movement powered by the main assembly carrying the chain fusee, barrel and center wheel as well as the Earnshaw­type spring detent escapement with Mercer's auxiliary compensated balance and steel/palladium helical balance spring. Mercer's auxiliary balance wheel was a modification of the Molyneux– Eiffe balance which was particularly effective through a wide range of temperature variations. If one looks at the balance wheel there are two bimetallic laminae attached to a crossbar that act in hot temperatures and are limited or stopped by means of screws that resist the balance rim in cold conditions. The rim of the movement contains serial number 13496 which is thought to date from the late '20s or early '30s.

Condition: Case – In excellent condition with no major damage. The only thing I do not see is an identification name or number on the case. Dial ­ Very fine with just a bit of scuffing at the very top of the minute ring.

Movement – Excellent. This is a fine example of the work of the brothers Thomas Jr. and Frank Mercer of St. Albans who were amongst the world leaders during the 20th century in making mechanical instrumentation for the purpose of quality control. the firm played a major role for the allies during World War II when the serial numbers were in the 16000 range.