Marine: Marine "box" chronometer accuracy

Discussion in 'Chronometers' started by burt, Sep 8, 2015.

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  1. burt

    burt Registered User
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    I recently received an email from clock maker Bernie Tekippe of Atlanta Georgia. Bernie makes his own design of precision regulator which is capable of accuracy of .008 +/- seconds per day. Bernie had read my article on the Negus marine chronometer #1273 in the Sept/Oct 2015 Bulletin. He wrote to tell me he liked the article and of a lecture he attended many years ago given by the late Dana Blackwell. Blackwell was commenting on the Venus transit expeditions and that he learned the "box" chronometers used on that expedition preformed better than many of the precision regulators some of the scientists elected to use. While the observatory instruments could normally out preform the portable chronometers they needed their massive concrete support bases and temperature controlled rooms to gain the advantage. In the field and set up on less than perfect platforms they were not capable of their inherent accuracy or performance. This no doubt because of the very sensitive to disturbance pendulums they used.This is where the more portable and more robust box marine chronometer had the advantage. How would it have ever been possible to survey and explore the American West without the portable and accurate box chronometer? While designed for navigation at sea the marine or box chronometer found many other uses. These timekeepers were, when properly adjusted, capable of keeping very accurate rates of time and certainly good enough for successful navigation at sea, hydrographic/ geographical survey work and scientific expeditions.
     
  2. doug sinclair

    doug sinclair Registered User

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    This might be a simplistic view of how these surveys might have been made possible. Perhaps, before box chronometers (aka marine chronometers), surveyors would have perhaps used the same instruments as mariners had. The advantage on land is that, once you had figured out your co-ordinates, you were likely still in the same place! You weren't concerned with calculating speed and direction, and you weren't on a pitching deck. The terrain around you offered all sorts of landmarks that might be included on the charts you were making. Quite unlike the tractless surroundings that the mariner had to contend with. If you were unable to take a reading on a particular day, it was easier to stay where you were until you could take a reading. Anyway, that's how I see it.
     
  3. Luis Casillas

    Luis Casillas Registered User

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    One thing that would perhaps be valuable here is to assemble a bibliography of references that contain detailed performance records of chronometers. I'll throw one in to start us off:

    • Whitney, Marvin E. 1984. The Ship's Chronometer. American Watchmakers Institute Press.
    This contains reproductions of original trial records for a number of chronometers and similar timepieces. Many of them were tested by the author himself at the US Naval Observatory. It also has a very interesting chapter on chronometer trial scoring systems.
     
  4. doug sinclair

    doug sinclair Registered User

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    One might add:

    -The Illustrated Longitude, Sobel & Andrewes
    -Time Restored, Betts
    -The Marine Chronometer, it's History & Development, Gould
    -Two Bureau of Ships Manuals on Hamilton models 21 & 22
     
  5. Luis Casillas

    Luis Casillas Registered User

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    Thanks for the references!

    Question: how does The Illustrated Longitude differ from the regular edition, and from this book:


    • Andrewes, William J.H., editor. 1996. The Quest for Longitude: The Proceedings of the Longitude Symposium, Harvard University, Cambridge, Massachussetts, November 4-6, 1993. Harvard University: Collection of Historical Scientific Instruments.
    I remember seeing reviews that recommended this over Sobel, but perhaps the illustrations in the one you've recommended make it worth having as well?
     
  6. doug sinclair

    doug sinclair Registered User

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    #6 doug sinclair, Sep 9, 2015
    Last edited: Sep 9, 2015
    The ones I listed, I own. I don't know the one you refer to. But I can offer this. Will Andrewes and Dava Sobel were both presenters at the Longitude Symposium in Cambridge, Mass. in 1993 (?). After that symposium, both went their own way. Andrewes wrote The Quest for Longitude that you refer to, and Sobel wrote the original (small) version of Longitude. There was such a groundswell of encouragement from the public for a longer, in depth version of Longitude, that Andrewes and Sobel pooled their material, skill as writers, and ability to ferret out more information, that The Illustrated Longitude to which I refer, was compiled, co-written, and published. I have Sobel's original mini-Longitude, and enjoyed it so much that I jumped on the Illustrated Longitude when it became available.

    The reviews you read that recommended Quest for Longitude over the Sobel book, might be referring to Sobel's original work. I am not aware of such critical comment as may exist, comparing the Quest for Longitude with The Illustrated Longitude which they do-wrote.
     
  7. Tom McIntyre

    Tom McIntyre Technical Admin
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    Will did not write the Quest for Longitude, he is the editor and compiler. The book is the collection of submissions from the presentations at the Longitude Symposium Many attendees purchased advance copies at the Symposium that were delivered quite a few years later after all the manuscripts had been accumulated and a few permissions were sought and granted.
     
  8. Rich Newman

    Rich Newman Chair
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    We've all at one time or another assumed by reading chronometer books that tout the great chronometer makers like Harrison, Arnold, Earnshaw, Mudge, etc., that the machine was invented and "poof" longitude was solved. That's complete nonsense. The best book I've read on the topic is rather recent, 2014, from the Royal Museums Greenwich called "Finding Longitude" by Richard Dunn and Rebekah Higgitt. It's an excellent resource that really sets the record straight on the development and adoption of chronometers.

    To Burt's thread, it would be relatively easy to explore the American West without a chronometer. While absolutely helpful to have, instruments not subject to easy damage were always taken on expeditions including the Lewis & Clark 1804 expedition that was meticulously provisioned with many instruments including astronomical tables and an Arnold chronometer (that was lost). The chronometer apparently had variations so was an issue. Astronomical methods were absolutely reliable for navigation on land, the issue at sea of course was the moving ship and not having the luxury for weather to clear for observations. Regarding chronometers, they were rare to have throughout the 18[SUP]th[/SUP] century, the huge expense, reliability and adoption to new technology was a big issue - - all the early important English explorations always had more than one due to reliability (human and mechanical) issues, often three or more, and dead reckoning was still the standard for merchant shipping way into the 1800's.
     
  9. doug sinclair

    doug sinclair Registered User

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    So very true! The ship that brought John Harrison back to England from Portugal I believe was the same ship (without H1) that was lost some years later as it tried to find Juan Fernandez Island. I very much doubt that one ship in a thousand would have had a chronometer prior to 1800 or so. Leaving dead reckoning as the means of navigation. Solving the longitude was restricted to luck, and the ship that had a working chronometer, and proficient navigator. At least, that's how I see it.
     
  10. Tom McIntyre

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    Dead Reckoning is correct, but the actual form used was to "sail the latitude." Doing so, reduced the error to just the log accuracy and eliminated the computational errors of spherical trigonometry that not many were up to handling.

    Latitude had been easy to find in the 16th and 17th centuries. Prince Henry the Navigator described the technique (1394 - 1460).

    With knowledge of Longitude, it was possible to sail a direct route between points a and b on the globe arriving at the destination much quicker.
     
  11. Luis Casillas

    Luis Casillas Registered User

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    I remember reading through some of the writing on this topic and being left with the lingering suspicion that there was a big pro-chronometer, anti-lunar distances bias running through a lot of the secondary sources.

    Another one for the reading list! Thanks!

    As I understand it so far, the use of chronometer ensembles was by no means a peculiarity of those early days. When a timepiece becomes erratic, you need to be able to compare it to at least two in good order to pinpoint the bad one. If I recall correctly, Mercer's Chronometer Makers of the World mentions that for this motive in the early 19th century the Royal Navy would issue two​ chronometers to expeditions whose captains already owned a chronometer of their own, and only one to other expeditions.

    Whitney also mentions that even in the 20th century, navies were not at all able to issue chronometers to all their ships. The French Navy around the turn of the 20th century would issue lever timepieces for shorter journeys (e.g., to France's African colonies) and chronometers for longer ones (e.g., to Hong Kong). He also talks a bit about the number of timepieces and type (spring-detent chronometer vs. lever watch) allocated to different classes of US Navy ships.

    So if anything, I would guess that the practice of using multiple chronometers in one ship probably became more common, not less, as chronometers became more common. And also, the existence of lever timepieces for navigation suggests that chronometers were never made in enough (spring detent) chronometers to outfit every ship that could have used one. Though the development of wireless time broadcasts probably figures into the equation as well in the 20th century.

    It's also worth mentioning that clock ensembles remain standard practice for precision timekeeping to this day. Cesium atomic clocks are often run in ensembles, not just for detecting erratic clocks but also because there are statistical techniques for partially averaging out the random instability of multiple clocks. For example, the US Naval Observatory's master clock is in fact an ensemble of a few dozen atomic clocks:

    http://www.usno.navy.mil/USNO/time/master-clock/precise-time-and-the-usno-master-clock
     
  12. Snapper

    Snapper Registered User

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    Interesting thread. I have always had a fascination for precision timepieces, particularly the marine chronometer of which I have a very modest collection.

    Anyway to add a couple more publications to the list above:

    "The Mariner's Chronometer, structure, function, maintenance and history." by W J Morris
    and John Cronin's "The Marine Chronometer, its history and development". (No, not Gould's masterpiece!).
     
  13. doug sinclair

    doug sinclair Registered User

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    I just finished re-reading Dava Sobel's pocket version of Longitude. On page 164, she indicates that, in 1860, when the Royal Navy had fewer than 200 ships, it had close to 800 chronometers. To say nothing of the great number of ship's captains that owned chronometers. She also said that, in 1831, when H M S Beagle set out to fix the longitude of foreign lands, it carried 22 chronometers, six of which were owned by Captain Robert Fitzroy, plus five which he borrowed, the rest being supplied by the Admiralty.

    Some survey ships carried as many as 40 chronometers! Two or three was more common.

    This says nothing of chronometers that might have been owned by merchant marine, private shipping companies, private owners, and others. She also says traditional means of navigating existed long after marine chronometers be came common in marine usage.
     
  14. Luis Casillas

    Luis Casillas Registered User

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    I just received my copy of this yesterday, started reading it and it's hard to put it down. I wholeheartedly second this recommendation!
     

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