A self-taught cabinet maker and watchmaker, the Englishman John Harrison marked the 18th century – and, beyond that, the entire history of watchmaking – thanks to two major inventions: the pendulum and the marine chronometer. Formerly watched with circumspection by his peers, he has, over time, integrated the pantheon of the great names in watchmaking.

John Harrison, or the art of designing timepieces made of wood

The peculiarity of the great inventors is to be able to defy time. John Harrison is one of them. In April 2015, the National Maritime Museum in London hosted the presentation of a Guinness Book of Records award to the “Most Precise Pendulum Clock”, a watch known as “Clock B”, designed by Harrison … 250 years ago! This timepiece proved, in fact, that it could be accurate to within one second over a period of 100 days. A project that at the time was considered “so incoherent and absurd” that it was getting closer to “the symptoms of madness” (read in this article in English).

This anecdote, on its own, sums up perfectly who John Harrison was: a genius of his time, ignored by his peers, whose innovative and meticulous work will only be recognized much later.

Man has, all his life, embodied a sort of logic of precision. So much so that he died the exact birthday of his birthday, March 24, 1776, in London, at the age of 83 years. Coming to the world in Yorkshire County, the young John Harrison is very interested in watchmaking. And for good reason: at age 6, the boy, suffering from chickenpox, is sentenced to spend long days in bed, locked in his room. To distract him, his parents offer him a watch, which little John explores for hours. This is the beginning of a passion that he will perfectly accommodate with his other talent: cabinetmaking.

As an adult, Harrison distinguishes himself by making wooden clocks, which are opportunities to produce innovative mechanisms. Around 1720, he honors an order placed by the city of Brocklesby Park for a new clock: his creation, all in oak wood and guaiac, is decked out with a house invention, the “grasshopper escapement”, a movement devoid of friction that does not require lubrication. Then, between 1725 and 1728, with the help of his brother James, also a cabinetmaker, he designed three pendulum clocks – another invention of his own. The bimetallic pendulum pendulum, resistant to temperature changes, will become a major creation in the history of watchmaking.

But the other invention that will make Harrison famous, to which he will literally devote most of the rest of his life, is the manufacture of marine chronometers. An object that has profoundly changed the way of sailing.

Here is a selection of the watchmaking inventions that we owe to Harrison:

  • The bimetallic grill clock made of steel and brass – an alternative to George Graham’s mercury clock.
  • The “Grasshopper Escape”, a recoil escapement for pendulums – but so difficult to adjust that it will be used primarily by Harrison himself.
  • The birch bearing.

History of the invention of the marine chronometer

In the field of maritime exploration, the precise determination of longitude (the east-west position of the ship) has always been a problem, causing sometimes very large differences in direction. To solve it, scientists have been exploring two solutions since the sixteenth century: the first is to use the position of a celestial body like the Moon; the second requires the use of a precision clock, aboard the ship.

Among other European states anxious to remedy in a sustainable way, the British government launches a contest rewarding the first one who will find a way to achieve a correct calculation of longitude: it is the Longitude Act, voted in 1714, and proposing a very high remuneration of 20,000 pounds to the winner.

In the wake of Henry Sully who proposed his own invention to the French Academy of Sciences, the “sea watch” in 1716, Harrison launched in 1730 in the design of a marine chronometer. Supported financially by the clockmaker George Graham and astronomer Edmond Halley (the comet), Harrison works for five years to present the H1, his first ever marine chronometer. He embarked in 1736 for a crossing to Lisbon, then back, calculating, with the help of his invention, the exact position of the ship. Impressed, the Board of Longitude Board of Judges, who was in charge of judging the candidates, awarded him a 500-pound bursary to continue his research – to get the full award, the method had to be tested in a transatlantic crossing.

There follow two more compact and more precise versions, the H2 and the H3. The H2 is finalized in 1741, after three years of work, but a war between England and Spain is triggered then that prevents it from carrying out the experimentation at sea. The forced waiting gives him the opportunity to work on his H3, with which he corrects an error of design of the pendulums specific to the H2.

Inspired by a new escapement that he designed for a precision watch in 1752-1753, Harrison set out to build the H4 chronometer. This titanic work takes him six years. Completed in 1759, this chronometer, called “sea watch”, comes in two silver hulls, with winding, for a total diameter of about 13 cm. It’s past time for this life-size test: Harrison sends his son, William, to prove the reliability of the H4 on a trip to Jamaica. On arrival, the stopwatch error is only 5 seconds, or 1.25 minutes in longitude. The British Parliament believes that this is not sufficient proof. A second trip takes place to Barbados with the same William and the same stopwatch. This time, the error is 39 seconds, about 15 km. But it should be noted that each time, the error detected by the chronometer was infinitely less important than that of the calculation, performed in parallel, based on the position of the Moon. Once again, he was refused in 1765, offering him only half the price.

It was only in 1773, and in favor of the H5, the latest version of the marine chronometer, that the Parliament will eventually pay Harrison his just reward … Which still only reaches half of the total reward planned! And this is made possible only by the intercession of King George III, solicited directly by Harrison, and positively impressed by the results of H5. Harrison is then 80 years old.

John Harrison’s place is in a museum


Although rewarded during his lifetime, in 1749, by the Copley Medal for his watchmaking, Harrison suffered from his whole existence of a certain lack of consideration, including the obstinacy of the Board of Longitude and the reactions to his project. “Clock B” were just examples. It was not long after his death that his genius was recognized at its fair value. 

After the First World War, Harrison’s clocks were rediscovered by a retired naval officer, Rupert T. Gould: they were picking up dust somewhere in the Royal Greenwich Observatory. Gould has given much of his time to research and restore these precious timepieces. He also published in 1923 a book that continues to be authoritative in his field: Detailed history of the chronometer and its pioneers, in which he leaves a large space for Harrison’s inventions. 

Now, the watchmaker and cabinetmaker of Yorkshire has its place in museums. His wooden clocks and clocks are on display at the Leeds Museum and Galleries, Science Museum, Nostell Priory, and the Worshipful Company of Clockmaster’s Collection. As for the marine chronometers, they found their place in the observatory of Greenwich, in London. An observatory founded in 1675 by Charles II to solve the problem of calculating longitude at sea.