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John Harrison's timekeeper No. 4, constructed in 1759. On exhibition at U.S. Naval Observatory, 1963, through loan by British Admiralty. Forerunner of modern marine chronometer, this timekeeper gained for Harrison an award of 20,000 pounds offered by Parliament in 1714 for finding longitude at sea. Dr. Wm. Markowitz, Director of Time SErvice Division, U.S. Nval Observatory, at left and Mr. William P. Roseman, Head, Chronometer Workshop, Royal Greenwich Observatory, England, at right of timekeeper.
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