Berthoud, Ferdinand (1727–1807)

Swiss clockmaker and maker of scientific instruments. He improved the work of John Harrison, devoting 30 years to the perfection of the marine chronometer, giving it practically its modern form.

Berthoud was born near Couvet, Neuchâtel, and was apprenticed to his clockmaker brother Jean-Henri at 14. In 1745 he went to Paris and in 1764 was appointed horologer to the navy. He made over 70 chronometers using a wide variety of mechanisms, and wrote ten volumes on horology.

If navigators did not know the time at the zero meridian, it was impossible for them to plot their precise position, so accurate chronometers were vital. Clocks made by Berthoud were tested at sea 1768 and 1769 and showed variations in their working of about 5–20 seconds a day.