1693-1776, horologist and clock-maker, English

1713 - earliest extant clock.

1726 - first heard of the

1714 Longitude Act.

1735 - completed construction of his 'sea clock', H1.

1736 - sent on a voyage with H1 to determine the longitude of Lisbon.

1739 - after being awarded £500 by the Board of Longitude, completed construction of H2.

1749 - awarded the Copley gold medal by the Royal Society for his experimental work.

1759 - completed H3.

1760 - eventually produced his fourth timekeeper, the H4, the size of a large pocket watch.

1761 - H4 was sent on a trial to Jamaica.