National Museums Scotland acquire rare sea clock

The Bruce-Oosterwijck longitude pendulum sea clock, one of only two examples in the world, has been acquired by National Museums Scotland. The clock is the first mechanical attempt to crack the case of how to calculate longitude during long transatlantic voyages. It didn’t work. Scientists, naval experts and clockmakers would spend another hundred years trying to solve the problem of longitude, but this first failure marks a pivotal moment in maritime history.

Latitude (the north-south position) can be calculated by the height of the sun and stars in the sky; navigators had that one figured out thousands of years ago. Longitude (the east-west position) was a much harder nut to crack because it required a timepiece that could keep accurate time during a voyage that would allow sailors to calculate how far east or west they’d traveled from their point of origin.

Alexander Bruce, 2nd Earl of Kincardine, commissioned the clock in 1662 from The Hague clockmaker Severyn Oosterwijck. The pendulum clock had only been invented a few years earlier and was by far the most accurate timepiece ever created up until that point. (It would remain the most accurate timekeeper until the 1930s.) Oosterwijck had played an important role in its development by horologist Christiaan Huygens. Since the pendulum kept such precise time for so long, perhaps it could solve the longitude problem.

The first practical pendulum clock was invented in 1656 by the Dutch mathematician and astronomer Christiaan Huygens (1629–95). He then turned his attention to the creation of an accurate sea clock for the determination of longitude.

Huygens collaborated with Bruce on the project, with the Scot introducing a number of new features to the Dutchman’s designs before having four sea clocks made, two of them by Severyn Oosterwijck.

By the end of 1662, Bruce’s initial sea-trials were proving promising. More formal sea-trials were carried out, with reports suggesting that the clocks had performed exceptionally well.

However, these reports eventually proved to be inaccurate. Captain Robert Holmes, who had been entrusted with the trials of the clocks (though his attention was clearly more devoted to plundering Dutch merchant shipping), had reported implausible success beyond even the best hopes for the clocks. Samuel Pepys was asked to investigate, and it transpired that the glowing reports were entirely fictitious. Despite the optimism of the 1660s and extensive discussions over patents and profits, the new marine timekeepers turned out not to be the solution that had been hoped for.

Its mission failed, the Bruce-Oosterwijck clock fell into obscurity. It was probably used as a normal household clock from around 1670 through 1972 when it appears again on the record. It was valued as a late 17th century pendulum clock, but its true significance wasn’t discovered until recently.

Thanks to sizeable grants from the National Heritage Memorial Fund and the Art Fund, National Museums Scotland was able to acquire the Bruce-Oosterwijck sea clock. It will go on permanent display in the Earth in Space gallery at the National Museum of Scotland in Edinburgh.

5 thoughts on “National Museums Scotland acquire rare sea clock

  1. The discovery and purchase of the Bruce-Oosterwijck clock is a fascinating story, and (I note with some pride) is another example of 17th century Scottish innovation. Sad that the clocks failed as marine chronometers.

    The practical marine chronometer for calculating longitude was invented by an English carpenter and clockmaker named John Harrison. His H1 model was trialed in 1736. Harrison kept improving his clocks hoping to win a substantial prize offered for the first accurate chronometer to correctly calculate longitude. Harrison’s H4 was tested in 1763-64, and finally accepted by the government in 1765.

    All four of Harrison’s original clocks are on display at the Royal Observatory in Greenwich, and several are kept working. I had the pleasure of seeing them tick away in person many years ago. They are absolute jewels of craftsmanship and the work of a true genius. Harrison’s story is found at the Royal Observatory web site: . A more detailed article with more clock photo is at .

    John Harrison and his clocks were the subject of LONGITUDE, a Granada/A&E television series in 2000. Harrison was played by Michael Gambon (the second Albus Dumbledore). Jeremy Irons played Rupert Gould, the 20th century horologist who restored Harrison’s clocks. The television program was based on Dava Sobel’s 1995 book of the same title. The series is still available on DVD, and is well worth adding to any historian’s library.

    Mungo Napier, Laird of Mallard Lodge (SCA)
    (aka Garth Groff)

  2. What I want in the world is a Museum of Good Fakes – of genuine, scholarly copies of (say) a thousand, or ten thousand, items of great archaeological and historical interest. The point would be that visitors could handle them; indeed in the case of mechanisms would conceivably even be allowed to dismantle them.

    The fact that in current museums we must stare passively at things is, I have always found, a great frustration. I want to get my hands on ’em. Here’s a wonderful opportunity for some great philanthropist/benefactor to make his name immortal.

  3. Dearieme,

    May I suggest that you join the SCA or get engaged with some other re-enactment group. We do a lot of experimental archaeology, or “learning by doing”, and then share our learning by teaching others in formal or informal classes. My own research/teaching has been building replica Tudor war arrows using only hand tools and where possible period materials. I also used data provided by the Museum of London to study the socket sizes of medieval arrow heads and discover if the lighter arrows I shoot could have existed in the middle ages (answer: “yes”). I have also researched and built Scottish targe shields, and hope to delve into this further the next time I’m in Scotland. There is a whole world of knowledge out there to discover and share.

    Yours Aye,


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