John Harrison, a British watchmaker and inventor best known for having devised a system for determining longitude at sea, was born on April 3 325 years ago.

John Harrison H1 Marine, 1735

The invention of his marine chronometer was instrumental in the development of navigation starting in the eighteenth century and, together with other technologies, helped enormously extend the possibilities of navigation and orientation on the high seas. His father was a carpenter, from whom he learned various carpentry techniques. While attending the village schools, he became passionate about mechanics and when he was twenty he built his first watch, without ever having practiced with a watchmaker. It was a pendulum clock made entirely of wood. Building further models allowed him to practice and improve his knowledge of watchmaking.

George Harrison H2, 1739

In 1714 the British government created the Office of Longitude, offering 20 pounds to anyone who found a way to make it easier to calculate longitude while traveling, at distances greater than 30 miles from the coast. Harrison accepted the challenge and began work on a first marine chronometer in 1728, completing the job in 1735.


In the following years he would have created even better ones, smaller and cheaper than the first model. Thanks to his invention, Harrison made a fundamental contribution to making shipping safer, offering a very important advantage to the British Navy and commercial ships.

His most famous marine chronometers are 5 and are named Harrison 1, 2, 3. All specimens are kept at the Greenwich Observatory in perfect working order, except for the H4 which requires continuous lubrication to remain active without being damaged. the gears. Harrison died at 83 after dedicating a lifetime to calculating his position in the world thanks to the passage of time.

John Harrison H4, 1759