Lastly, John Harrison developed a number of working prototypes of the marine chronometer, culminating within the H4 in 1761, which served as the idea for enhancements by LeRoy and Berthoud, amongst others. Whereas constructing his earlier fashions, H1 by way of H3, Harrison developed a sequence of difficult innovations meant to compensate for motion and adjustments in temperature at sea. In H4, he lastly deserted these, growing a small spring-driven motion with a stability wheel that would oscillate at a better frequency than the stability wheel in a standard watch, which made it rather more usable on a ship. The photographs beneath present postcards in our assortment from the Royal Observatory and the Nationwide Maritime Museum, each in Greenwich, England. They depict John Harrison (picture 8) alongside along with his 4 prototype marine chronometers, H1, H2, H3, and H4 (picture 9).
