When John Harrison (1693-1776) completed his marine chronometer H4, he forever changed navigation with a revolutionary timekeeper that solved the issue of determining longitude while at sea. While today’s sailors use satellite navigation, ancient mariners struggled to determine their positions and heading at sea, with countless shipwrecks and lost lives motivating merchants, the scientific establishment, and nations to find a solution for determining longitude. The elusiveness of finding longitude at sea had reached mythical proportions – analogous to the search for the fountain of youth.

Completed in 1759 after nearly 30 years of development, H4 was Harrison’s 4th iteration built up from his understanding and development of three prior timekeepers he created. Moving from relatively large clocks to this final, hand-held chronometer, Harrison improved timekeeping precision, invented a device to take variability out of parts manufacturing, and most importantly, developed a bi-metallic correcting curb for the balance spring using principles applied from his earlier clocks. This revolutionary discovery permitted the watch to compensate for the extreme temperature changes experienced at sea, allowing H4 to lose just 15 seconds over 156 days at sea. H4 and those chronometers that followed revolutionized maritime navigation well into the 20th century, with deck watches becoming a ship’s most important navigational tool.

Hydrography is the surveying and charting of bodies of water, which serves as another important component for marine navigation. In 1795, the British Admiralty appointed their first hydrographer to produce sailing charts for the Royal Navy, and from these beginnings the United Kingdom Hydrographic Office (UKHO) was created. Part of the Ministry of Defence, the UKHO was tasked with supplying operational support to the Royal Navy, commercial shipping, and protecting the marine environment.

The present Ulysse Nardin deck watch, made in 1942 during World War II, and used by the British Hydrographic Service, is a lovely example of one of these important shipboard, navigational chronometers. Marine chronometers were the ultimate “tool” watches of their day, and have long been sought after by collectors both for their extreme timekeeping precision, high quality movements, as well as their historical importance. Unlike civilian pocket watches, deck watches were heavier and sturdier made to survive exposure at sea, and usually found in a silver case, which was more resilient compared to other metals.

Encased in its original wooden box and measuring a substantial 56 mm in diameter, its overall quality is outstanding. It’s fitted with a pristine and highly legible enamel dial with elegant blued steel hands. Inside, is a precision movement, featuring a state-of-the-art escapement with Guillaume balance wheel and blued-steel hair-spring ensuring maximum accuracy across the range of temperatures expected at sea. With a superb indirect center seconds complication and adjusted to five positions, its Extract from the Archives confirms the watch as “Top Class” – the very best quality to be produced by Ulysse Nardin. The case back is engraved “H.S. ↑2”, an indication it was used by the British Hydrographic Service, and further confirmed on the extract.

Generously donated by Ulysse Nardin and preserved in excellent overall condition, it is being sold to benefit HSNY’s ongoing education initiatives, in support of international traveling and virtual education programs, scholarships for students of watchmaking, and awards to watchmaking schools.