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Top 10 Amazing Facts about John Harrison

John Harrison was a self-educated English carpenter and clockmaker from the 18^th century.

He invented the marine chronometer, a long-sought-after device for solving the problem of calculating longitude while at sea.

His solution transformed navigation and greatly increased the safety of long-distance sea travel. The tools helped sailors navigate with precision.

Harrison’s innovation was timely since it happened after the Scilly naval disaster of 1707. The disaster led the British Parliament to offer him a financial reward of up to £20,000 under the 1714 Longitude Act.

It took another 50 years to perfect his innovation and thus saved countless lives.

Learn more about him in the top 10 facts about John Harrison below.

1. Harrison first worked with his father

Harrison was the first of five children and his family lived in the Lincolnshire village of Barrow upon Humber. His step-father was a carpenter that worked in Nostell Priory estate.

As the firstborn, John worked at his father’s workshop and spent his free time repairing clocks. Harrison’s interest in clocks started when he was about six years old. To keep him distracted while recuperating from chickenpox,  he was given a clock to play with. 

Together with his brother, James, they made several clocks, one with a frictionless, ’almost continuous-impulse, grasshopper escapement and compensating bimetallic gridiron pendulum.

The brothers also used cycloidal cheeks and maintained power as Huygens had done.

2. I have the solution! Well not exactly what Harrison said to Edmond Halley

Photo by Mika Baumeister on

Harrison came from a humble family; a carpenter father and not much is said about his mother. Furthermore, there are no records of his education.

While not much is known about his upbringing, what is certain is that Harrison was self-educated and loved working on clocks. His love for numbers made him learn mathematics, astronomy, physics, metallurgy, and mechanics.

In 1720 Harrison created a grandfather clock that was accurate to one second per month. This was an unthinkable precision in those days.

Additionally, Harrison devised a maritime clock that was used on a ship to accurately keep time regardless of weather, temperature, or rough seas.

He pitched his idea to England’s Astronomer Royal, Edmond Halley, a member of the Royal Society. While Halley was impressed by his ideas and drawings, he declined to introduce Harrison to the Board of Longitude.

3. It took Harrison 16 years to complete the manuscript of his inventions

In 1714, the United Kingdom parliament offered £20,000 to anyone who could create a reliable, accurate method of finding longitude at sea.

Harrison was convinced by George Graham to take an unsecured loan to invest in his clock business.

Sixteen years later, in 1730, Harrison completed a 23-page manuscript on experiments and inventions applied to clocks and outlined a timekeeper for use on ships to determine longitude.

All this time, he was aware of the prize offered by Parliament in 1714. He submitted his first chronometer in 1735 for the prize.

This invention was followed by three more instruments, each smaller and more accurate than its predecessor.

It was in 1762 that his famous No. 4 marine chronometer was found to be in error by only five seconds after a voyage to Jamaica.

4. Harrison’s first Marine clock was complex

Harrison’s second sea clock (H2). Photo by Jonathan Cardy –

He returned home and produced a heavy marine clock using his earlier inventions. This clock had two interconnected bar balances designed to be immune to the lurching of a ship.

It was tested in 1737 on a voyage to Lisbon. The clock correctly indicated the ship’s position to be off the Lizard, 57.5 nautical miles further west.

5. All Harrison knew to do was work!

There is a portrait of Harrison dating back to 1770 showing an aging watchmaker’s thin lips distinctly downturned.

He was always working. The author of his autobiography described him as always working and never once use the words happy, joy, or contentment to describe Harrison.

It was only once when the author used the word satisfaction. This was when Harrison got an idea for solving the Longitude Problem worth pursuing.

Harrison worked on the clock for 19 years and this caused a strain on his relationship with his family. Even at 72, Harrison was still bent on working.

6. Seen as a commoner, Harrison had to prove himself to his mentors

Harrison’s Chronometer H5, (Collection of the Worshipful Company of Clockmakers), in the Science Museum, London. Photo by Racklever – Wikimedia

The English society was dominated by powerful elites to whom birth, title, and education mattered. To put it simply, Harrison was a commoner and came from an unknown family.

While preparing to present his marine clock idea to the Board of Longitude, he was advised by Halley to first share it with George Graham, Graham was the premier clockmaker in England, to gain his support.

The next day, Harrison met Graham about to open his London clock shop. Their first encounter was rather embarrassing and degrading for Harrison, he was dressed like a delivery man.

Harrison quickly informed him he had been sent by Edmond Halley. He was invited in.

Halley and Graham later became powerful mentors and guides for Harrison. They were going to be very useful in influencing members of the Board of Longitude.

7. Hold up! There was no way the underdog, John Harrison, could solve the complex problem or so the Board of Longitude thought

Harrison came from a humble background and did not have any formal education. This background made the Board of Longitude doubt his ability.  

Others saw him as a threat to the elite group. To them, an uneducated commoner could not solve the greatest scientific problem of the age.

His lack of credentials made it even harder to convince the Board. Lucky for him, he had sought the help of Edmond Halley and George Graham.

To top it, Harrison used his greatest asset, his brilliant mind.

Still unconvinced by his background, the Board referred to Harrison as a mechanic, a sarcastic name for people who engage in physical labor.

8. Unfazed by the Board of Longitude’s almost deception, Harrison kept on improving his invention

The clockwork in Harrison’s H4 watch. Photo by Mike Peel –

Almost convinced, the Board of Longitude offered to give Harrison £500 to encourage further experiment. Harrison worked with his brothers to create a stronger and slightly smaller version of the marine clock.

Unfortunately, the clock did not meet the required standards and was not tried at sea. Shortly after, his brother James returned home from London.

Harrison was left to work on a third clock that was tested in 1757.    

Unluckily for Harrison, all the rights to his four clocks were owned by The Board of Longitude.  

9. King George III supported Harrison’s new invention

There were accusations that the Board of Longitude was unfair to Harrison. This reached King George who took Harrison’s side.

In 1772, despite his old age and failing eyesight, Harrison finished the fifth clock (H5). His first two watches required to be identical to the original H4. It took him three years to make H5 and two more years to test and adjust it.

With age quickly catching up with him, Harrison asked his 45-year-old son, William, to plead with the King of England since he was the only one who could not be questioned.

He delivered a letter to King George III explaining his frustrations with the Board of Longitude.

Harrison’s last clock was tested at the king’s private observatory at Kew. In 1773, the Board of Longitude dropped their opposition and awarded Harrison for his invention.

10. As a determined man, John Harrison worked on the watch for two decades

A John Harrison ship chronometer. Photo by Bjoertvedt –

Harrison only made £2,500 over that entire two-decade stretch. To get his due, Harrison spent several years fighting with the Parliamentary board. They only gave in after the intervention of King George III.

In 1773, at age 80, Harrison was given £8,750. Although the money came in handy in old age, Harrison did not own his patent.

The only feature of his chronometers used by later manufacturers was a device that keeps the clock running while it is being wound.