John Harrison (April 3, 1693 - March 24, 1776) was an English horologist, born in Foulby, Yorkshire, England. He invented the first accurate marine chronometer, enabling navigators to calculate their longitude accurately at sea.
During that era, sea navigation was risky due to the problem of longitude. The issue led to losing four ships and 1,300 sailors in the Scilly Naval Disaster in 1707. To find a solution, the British Parliament announced a reward of £20,000 to anyone who could find a way to calculate longitude while navigating at sea. Harrison, who was a self-taught clock-maker and carpenter, was up for the challenge.
To solve the longitude problem, Harrison thought of devising a portable clock that kept time to within three seconds per day. It made the method of time-keeping more accurate than the best watches during that time. In 1730, Harrison made his first chronometer and submitted it for the reward. The device was accurate, and sailors could use it as a portable time standard for computing longitude. Harrison’s next three chronometers were smaller and more accurate than the previous one.
In 1762, there was a voyage to Jamaica to test the accuracy of Harrison’s famous No. 4 marine chronometer. During the trial, it was found that the device was only five seconds (1 1/4′ longitude) short of the accurate longitude. Despite all the chronometers of Harrison meeting the set standards, he did not receive any reward money until 1763, when he received only £5,000. He was paid the full reward amount in 1773.
Once Harrison claimed that the marine chronometer he developed in 1735, which was powered by the motion of the ship, was accurate within a second after ticking for 100 days. He was ridiculed for that claim. After 250 years, in 2015, the Guinness World Records committee declared that clock as one of the most accurate pendulum clocks in the world. Harrison was proven right.