The History Leading Up to Precision Clocks
The earliest mechanical clocks, dating from the late thirteenth century, used verge escapements and had foliot instead of pendulums. They typically ran for a day, giving their owner a chance to reset them - since they were only accurate to about fifteen minutes per day. It was not until the 1400's that better metallurgy and improved gear cutting techniques justified the addition of minute hands on tower and chamber clocks. It wasn't until around 1670 and the development of the pendulum and the anchor escapement that it was possible to keep time to within 10 to 15 seconds a day.
It was about this time that commercial navigation provided the impetus to determine the longitude (east-west location) of ships at sea. In the ideal the search for longitude was perceived as a project of intellectual and humanitarian concern transcending national interests. By the early 1700's it was a competition between countries. France was more populous and richer, hence a stronger land power, than England. But England had the advantage on the oceans. For both countries the eighteenth century was a period of rapid growth of trade in and competition for what were known as the colonial wares: Sugar, coffee, tea, and tobacco. These commodities were the source of fabulous fortunes and windfall revenues. Their profitability depended on the efficiency and productivity of their merchant marines.