A10972

Dent Marine Chronometer with Airy’s Bar

£11,000.00

Signed   Dent    London   - Chronometer Maker to the Queen no. 2894  -with Airy's Compensation
Circa   1860
Diameter [dial]   102 mm         

1 in stock

Description

A mid 19th Century English two day marine chronometer by Dent with Airy’s bar in a mahogany box.  Full plate brass keywind fusee movement, four turned pillars secured by blue steel screws, engraved broad Ministry arrow.  Harrison’s maintaining power with blue steel click and spring, blue steel barrel ratchet wheel and double toothed click on the barrel bridge.  Plain brass cock, diamond endstone, two arm compensation balance with two circular weights and two timing nuts, Airy’s bar with two smaller circular weights resting against the rim.  Freesprung palladium helical hairspring.  Earnshaw spring detent escapement, escape pivots with endstones.  The movement secured to the gilt dial plate by three blue steel screws.  Engraved signed and numbered silvered brass dial with subsidiaries for seconds and power reserve indication.  Broad Ministry arrow in the seconds subsidiary, Roman numerals, blue steel hands.  Signed and numbered turned brass bowl, sprung hinged dust cover to the winding aperture.  Screw brass bezel with flat glass.  Brass gimbals and locking mechanism, numbered brass ratchet key.  Two tier mahogany box, the top lid having been removed in common with most Ministry marine chronometers.  Signed and numbered circular plaque with the broad Ministry arrow, folding brass handles.

A fine example of a 19th Century English marine chronometer.   Airy's bar was invented in 1871 by George Airy.  Its purpose is to allow for precise adjustment of the positioning of the weights along the balance rim.  Airy obtained Admiralty approval for an order directing all chronometers competing in the 1877 trials must be fitted with the device.  The Horological Institute objected to the order and its adoption was not made compulsory.  It is seldom found and often used incorrectly.  An almost identical example by Dent, No. 2459, is illustrated in Hans Staeger's book "100 Years of Precision Timekeepers", page 669.  Both chronometers have been later fitted with Airy's bar and had the fact engraved on the dial.  The engraving on 2459 is somewhat larger and more prominent.  Greenwich Observatory records this chronometer as having been purchased in May 1865 (part exchanging an Arnold chronometer).  Thereafter it served on a number of naval vessels:- HMS- Diamond, Tamar, Cyclops, Argonaut, Goliath and Mars.  Copy of the Greenwich records accompany the chronometer.

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