Words by Bremont Co-Founder, Giles English

To take your mind off the current lockdown, and to celebrate a great Briton who we as a business may not be here without, we are commemorating the birthday of the horological pioneer that was John Harrison. Born on 3rd April, in 1693, Harrison, like Shakespeare, actually died on the very same day of the year; a statistical phenomenon known as ‘the birthday effect’.

John Harrison was a genius engineer and master craftsman who invented a marine clock that enabled the measurement of longitude at sea. Up until 1761, when Harrison’s H4 clock went live in sea trials, there had been no accurate way of measuring longitude so sailors had literally been sailing blind only knowing their latitude with any certainty. The reason being that to measure longitude you need to know the time very accurately to be able to measure your position against the stars. Pendulum clocks were the only accurate clocks but, being so sensitive to movement and temperature, new technology was needed to make them work at sea. It was like envisaging the internet in the 1920s!

John Harrison's H1 Marine Timekeeper, image credit Royal Museums Greenwich

In 1709 there was the Scillian Naval Disaster where up to 2000 sailors were lost at sea coming back from a siege off the coast of France. This had devastating effects on the Navy and the government at the time. As Britain was a naval empire, the government brought in the 1714 Longitude Act to promote the science behind the measurement of longitude at sea and offered a reward of over £3m to anyone who could prove they could measure it. In many circles it was thought impossible and the mapping of the stars was at an early stage. However, the government was inundated with mad suggestions, such as using the direction that fish were swimming in or positioning static boats around the oceans with cannons on.

Enter John Harrison, a talented carpenter from Grimsby in the North of England, who was obsessed with clocks (he created a wooden clock that still runs today). He set out to create a clock that would have the required accuracy and in 1730 created his first patent. People doubted that a clock would ever be accurate enough or that it would take up most of the aft cabin of a ship like some colossus time machine, so he was battling against the sceptics. Eventually in 1761 he delivered H4 to the admiralty and it looked like a pocket watch with a diameter not much bigger than a saucer. Harrison, then aged 68, had been working on the project for over 30 years, but in the process had made a mammoth leap in watch/clockmaking. 

The original Bremont B1 Marine Clock, inspired by John Harrison

Harrison invented the gridiron pendulum, consisting of alternating brass and iron rods assembled so that the thermal expansions and contractions essentially cancelled each other out. Another example of his inventive genius was the grasshopper escapement – a control device for the step-by-step release of a clock's driving power. Developed from the anchor escapement, it was almost frictionless, requiring no lubrication because the pallets were made from wood. This was an important advantage at a time when lubricants and their degradation were little understood.


The H4 went on the sea trials and accumulated a loss of 3 minutes 36.5 seconds at the daily rate over the 81 days and 5 hours of the voyage which was the equivalent to 1nm of error. Captain James Cook used K1, a copy of H4, on his second and third voyages. With political hoops to jump through, further trials and a personal intervention from King George, it was over 12 years before he received the Longitude prize and by then in his 80s. The money was well received, but it was the recognition of his lifetime’s work that mattered to him more. 

The mechanics of the Bremont B1 Marine Clock

The early marine chronometers were often 30% of the value of the ships they travelled on and were owned by the admiralty. They transformed Britain as a seafaring nation, helping them to trade more efficiently, disseminate information quicker and be more efficient in battle. The impact on British watchmaking was also massively significant, you wanted an accurate clock you came to Britain and that is why so many inventions still used in mechanical watches came from the British. At one point we were making over 50% of the world’s watches/clocks until two world wars changed our manufacturing base forever. 


I hope this gives you a brief insight into one of my great heroes. John Harrison is listed in the Top 100 most influential British individuals of all time, and rightly so.


One of my reading suggestions for those in isolation would be a truly fantastic book by Dava Sobel, ‘Longitude’. Please do share your thoughts with us if you give it a go!


Inspired by John Harrison’s original Ships Chronometer Bremont builds marine clocks as a tribute to this great man. Our B1 and B2 Marine Clocks are made in England and are designed with some unique features not normally found in clocks which include; three time zones, 30 day power reserve, date and 90 day chronograph. In 2011, Bremont worked with iconic British musician and artist Ronnie Wood to hand paint the dial and internal case of a limited edition run of 'Art Clocks'. To find out more about Bremont's Marine clocks contact us directly at

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Great Britain has a wonderful history when it comes to watchmaking and has probably been the home to more advances in horology than any other nation. Bremont is determined to play a pivotal role in the reinvigoration of British watchmaking on these shores. Our goal has always been to bring back as much of the process to the UK as possible and our watches are all designed, manufactured and assembled in England.

Discover our latest range of mechanical watches...


Last year, friend of the brand Nick Butter became the first person to run a marathon in each of the 196 countries on earth. With his upcoming speaking tour having been postponed due to the current situation, he's been taking to the streets to help with food deliveries for those in need. Hear from Nick about how exercise is key during isolation and watch our quickfire Q&A film '60 seconds with...' which we captured upon his completion of 'Running the World 196'.
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