I’m a man of the clock. For as long as I can remember back I’ve lived by a timetable of one sort or another. More rigidly, or less so, depending on the circumstance. Shortly after I was toilet trained my Dad would wake me up at about the same time every night, in the middle of the night, to take me to go pee. Thus, I never wet the bed. This nightly by-the-clock exercise was living on a timetable, even at two years of age, to an extent.
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The study of time and timekeeping is known as horology.
Horology [from the Greek; “hṓra” for “hour” or “time”, and “logy”, study of] is the study of the measurement of time. Clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of instruments used to measure time. In current usage, horology refers mainly to the study of mechanical time-keeping devices, while chronometry more broadly includes electronic devices that have largely supplanted mechanical clocks for the best accuracy and precision in time-keeping.
In the frame of today’s diary, I’m looking at one specific aspect of chronometry, or precision timekeeping, during the late-1600’s/early-1700’s sailing days of yore, back when there did exist a relatively reliable way of determining a ship’s latitude at sea, or how far north/south the ship was relative to the equator at any point on the globe. However, accurately determining longitude, or how far east/west one had sailed from one’s starting point was not much better than an educated seat-of-the-pants guess. Before such things as GPS or inertial navigation, dead reckoning was the only method that even came close. Or, finally running into a known island or coastline on some continent.
In navigation, dead reckoning is the process of calculating current position of some moving object by using a previously determined position, or fix, and then incorporating estimates of speed, heading direction, and course over elapsed time.
The idea is simple: if you know what time you started (and your initial position, of course) and you kept with you an accurate clock, then as long as you know what course and speed you have maintained and for how long, then you should be able to very accurately calculate the distance you have traveled.
By the use of a sextant during the day or by knowing how to read star postions at night, along with a little trigonometry and reference to data tables, figuring out your latitude was well established. You could know, for instance, with little doubt that you were at Latitude 30o North, but where, exactly along that line circling the globe and parallel to the equator, were you? Measurements by sextant and star positions could not determine longitude.
So, with the combination of instrument measurements for latitude and dead reckoning for longitude, you could determine your exact spot out in the ocean. You know, that need-to-know stuff. But there was a problem. Clocks and watches of the day were dreadfully inaccurate, and clocks at sea were next to useless. Except maybe as small anchors or items of trade. Humidity and the rolling and pitching of a sailing ship rendered a pendulum clock as good as a stopped clock; perhaps accurate twice a day, but you never could tell when it was. Leave it to the Brits to do something damn serious about it. Solving this problem was worth money, a lot of money.
The Longitude Act 1714 was an Act of Parliament of Great Britain passed in July 1714 at the end of the reign of Queen Anne. It established the Board of Longitude and offered monetary rewards (Longitude rewards) for anyone who could find a simple and practical method for the precise determination of a ship's longitude.
As transoceanic travel grew in significance, so did the importance of accurate and reliable navigation at sea. Scientists and navigators had been working on the problem of measuring longitude for a long time. While determining latitude was relatively easy, early ocean navigators had to rely on dead reckoning to find longitude. This was particularly inaccurate on long voyages without sight of land and could sometimes lead to tragedy, as during the Scilly naval disaster of 1707 which claimed the lives of nearly 2,000 sailors. This brought the problem of measuring longitude at sea into sharp focus once more.
The Longitude Act offered a series of rewards, rather than a single prize. The rewards increased with the accuracy achieved: £10,000 (worth over £1.54 million in 2021) for anyone who could find a practical way of determining longitude at sea with an error of not greater than one degree of longitude (equates to 60 nautical miles (110 km; 69 mi) at the equator). The reward was to be increased to £15,000 if the error was not greater than 40 minutes, and further enhanced to £20,000 if it was not greater than half a degree.
John Harrison received more money than any other individual, with several rewards from the 1730s–1750s, and £10,000 in 1765.
John Harrison. His story is the story of the marine chronometer, and it’s one heck of a story.
Now, I could go on typing at length, using my own words to give you a summary of that story, but I do possess, on the rare occasion admittedly, the acumen to know when not to do that, and rather let someone else do it, because their telling of the story is so much better than any effort on my part could accomplish.
Do then, please, watch this entire video. It’s quite well done, succinct, and complete. Rather rare qualities as is more often not the case with something from YouTube.
For those who aren’t able to take the time for the video, this excerpt from the book Longitude (Dava Sobel, 1995, Walker and Company).
With no formal education or apprenticeship to any watchmaker, Harrison nevertheless constructed a series of virtually friction-free clocks that required no lubrication and no cleaning, that were made from materials impervious to rust, and that kept their moving parts perfectly balanced in relation to one another, regardless of how the world pitched or tossed about them. He did away with the pendulum, and he combined different metals inside his works in such a way that when one component expanded or contracted with changes in temperature, the other counteracted the change and kept the clock’s rate constant.
His every success, however, was parried by members of the scientific elite, who distrusted Harrison’s magic box. The commissioners charged with awarding the longitude prize — Nevil Maskelyne among them — changed the contest rules whenever they saw fit, so as to favor the chances of astronomers over the likes of Harrison and his fellow “mechanics”. But the utility and accuracy of Harrison’s approach triumphed in the end. His followers shepherded Harrison’s intricate, exquisite invention through the design modifications that enabled it to be mass produced and enjoy wide use.
An aged, exhausted Harrison, taken under the wing of King George III, ultimately claimed his rightful monetary reward in 1773 — after forty struggling years of political intrigue, international warfare, academic backbiting, scientific revolution and economic upheaval.
Lives saved, and you get to use GPS today. All thanks to an 18th century carpenter.
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