In October 1707, Admiral Sir Cloudesley Shovell wrecked four Royal Navy warships upon the Western Rocks of the Isles of Scilly, losing nearly two thousand sailors in a single fog-shrouded night because no navigator aboard could calculate their true East-West position.

The resulting Longitude Act of 1714 offered a king’s ransom of £20,000 for a practical method. Astronomers demanded complex celestial calculations of the Moon’s lunar distance; an unassuming Yorkshire carpenter named John Harrison instead built a clock of brass, oak, and lignum vitae.

The Board of Longitude was scandalised. How could a mechanical escapement surpass the celestial clockwork of Almighty God? Harrison’s fourth sea watch, the H4, proved accurate to within a fraction of a second across a voyage to Jamaica and back.

Alfred reminds us that accurate timekeeping transformed lighthouse beacons and global trade; Baxter simply notes that Harrison deserved a knighthood and a free bucket of cockles.