Swiss stainless steel chronometer deck watch Circa 1961

Stainless steel deck watch in a mahogany box
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A fine stainless steel Swiss, keyless, circuit-break lever chronometer deck watch, circa 1961. With power reserve indication and Guillaume balance. Accompanied by the fitted mahogany deck box with electrical terminals and outer mahogany travelling case. Made in April 1961 in a limited edition of 500 pieces. A polished massive bassine, bolt at 6 to activate the circuit-breaking, insulated pin for transmitting the signal, screwed-down back.

Matte silvered dial with radial Roman numerals, outer minute track, subsidiary seconds and 36-hour up-and-down scale. Blued steel spade hands. A frosted and gilt movement, 17 jewels, straight-line lever escapement, Anibal-brass Guillaume balance, blued steel Breguet balance spring, swan-neck micrometre regulator, escape wheel pinion fitted with a cam for contact- breaking each second. Dial, case and movement signed.
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Diameter: 64 mm
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Signed: Ulysse Nardin  Locle & Genève
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In a 1910 letter to the US Naval Observatory, Paul Nardin wrote that from 1883 to 1910 the company made only 50 circuit-break survey chronometers for scientific institutions worldwide. The circuit break (Survey) Chronometer was designed for surveying and mapping operations, solar observations, and scientific experiments in remote areas requiring accurate, audible time signals. The first circuit-break mechanism was installed in 1874 by the Negus brothers, chronometer makers from New York. Survey chronometers were superbly finished and adjusted, to meet the requirements of the surveying and scientific communities.