The obvious, but critical, point about the capital in which the Act of Longitude was passed was its size. It was a tiny fraction of modern London, still focused almost entirely around the City.
During the course of the 18th century, London expanded rapidly to incorporate new developments like Mayfair and Bloomsbury. But Belgravia, Chelsea, Fulham and Hammersmith remained well outside the city limits.
The 18th Century was good to the growing city. London became healthier, wealthier and considerably grander than the old wooden town that had gone up in flames in 1666. The new St Paul's was completed in 1708; Westminster Bridge - only the city's second after London Bridge - was completed in 1750.
The 18th Century brought newspapers and a regular police force to London: the first daily was published in Fleet Street in 1702; the Bow Street Runners were founded in 1749 by the author Henry Fielding. Coffee houses became popular, and began hosting stock and commodity traders and auctions, leading eventually to the formation of Christie's, Sotheby's and the London Stock Exchange.
The 18th century was the last golden age for wooden sailing ships, before the 1800s made steam and iron prerequisites for modern navies and trading fleets. It was a golden age too for maritime exploration, with the voyages of James Cook amongst others opening up the Pacific and the South Seas.
Onboard, however, conditions were very far from golden. Sailors lived in cramped accomodations, subsisted on dreadful diets of rock-hard ship's biscuit and putrified meat, and died in their thousands from scurvy, shipwreck, dehydration or drowning. Naval officers frequently treated their men - many of whom were press-ganged into service - to the harshest of discipline. Murderous naval engagements between the great European powers were commonplace.
Trade was, as it always has been, the key driver of seafaring activity. Britain in particular built her 18th-century fortune on maritime trade. The East India Company reached the apex of its political and economic power during the 18th Century. Vast flows of tea, silk, spices, saltpetre, opium and cotton crisscrossed the world in British merchant ships, protected by the Royal Navy.