Literary Meditations

A Mind's Journey

Dava Sobel’s ‘Longitude’ and Harrison’s clocks.

Dava Sobel’s Longitude narrates the stories behind the resolution of the longitude problem. Especially, attention is given to George Harrison’s efforts to find a technological solution to it and all problems he needed to face with the Board of Longitude. The horologist’s story is one of struggle, constancy and determination which will lead him to the creation of H4, a timeless masterpiece in scientific history.

Finding a solution to the longitude problem became always more pressing considering the growth of international trade in the 17th and 18th centuries. Indeed, shipwrecks caused by the lack of orientation due to the uncertainty of geographical position could no longer be tolerated considering the economic interests of these voyages. Although pendulum clocks already existed in the early 18th century, these would not work on a moving ship, becoming useless for finding longitude at sea. Measuring and mapping stars could help, but these methods were not enough accurate to find the exact longitude in open sea. By 1700, seamen could calculate their latitude but not their longitude.

In the year 1714, the British Government set high rewards for whoever was able to solve the longitude problem. By 1726, this news reached Harrison, who worked for nearly fifty years to solving this scientific dilemma. Harrison had humble origins, coming from a working-class family. Nevertheless, he learned by himself the arts of clock-making, creating his first clocks in 1721-2. His first major work was a turret-clock that needed no lubrication because done entirely from tropical wood; moreover, it also contained the “grasshopper escapement”, a new technological system introduced by the same Harrison. With the creation of his first clock, Harrison already presented two revolutionary changes ahead of his times. Afterwards, he started to create clocks that would not be affected by external temperatures.

Having heard about the Longitude prize, Harrison moved to London, finding support in Graham, the best watchmaker of his time. Harrison, in a time frame of nearly two decades, built his three marine timekeepers; although they carried great improvements and discoveries, Harrison started to believe that the solution lied in a different design. By 1760, he created H4, a watch instead of a clock; it had a “high energy balance” (the timekeeping element) that was less affected by the ship’s movements. H4 is a true jewel not only for its technological value but also for its refined design and the presence of precious stones (rubies and diamonds, to reduce friction into the watch’s mechanisms).

H4 was repeatedly and successfully tested; however, the Board of Longitude complicated things for Harrison, continuously postponing the reward. This was also due to the presence of Nevil Maskelyne into the Board’s commission; he was Astronomer Royal at Greenwich and worked himself on the longitude problem, believing that the solution lied mainly in the observation of celestial bodies. Harrison had to show the secrets of his watch to a tribune of judges, dismantling H4 piece by piece; his marine timekeepers were mistreated by the same Maskelyne, which kept them at the Greenwich’s Observatory to taste their capabilities once subjected to different temperatures. This not being enough, the Board asked Harrison to create a cheaper model of H4, because the original one was too expensive to reproduce on a larger scale. Kendall helped Harrison with this task, creating the H4’s twin, K1. The last was tested by Captain Cook during his second and third voyages in the Pacific, who considered K1 a perfect watch and a great companion during his journeys. Curious fact, K2 will travel with Captain Blight on the HMS Bounty, a voyage destined to become legend.

Finally, thanks to King George III’s influence, Parliament ordered that Harrison ought to be awarded the balance of the prize’s money ( he borrowed different sums to work on his clocks) in 1773. After this public recognition, Harrison died only three years later, just in time to see his masterpiece awarded for its merits.

Reading Sobel’s book is a journey in the past of science and technology, fusing together maritime, scientific and astronomical history. Her writing is crystalline clear, making the book easy to read even for people ignorant of scientific topics. Moreover, it is full of details and facts which make the story interesting, involving and entertaining for the reader, creating a natural sympathy towards Harrison, a lonely genius with an invincible determination.

If you haven’t read it yet, consider to do it. You will not be disappointed.

See you for the next adventure!


Atena Longo


P.S. I read Sobel’s book after visiting the Royal Observatory at Greenwich, where it is possible to admire H1, H2, H3 and H4 all in one gallery. Here below a picture of H4:



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