Pocket Chronometer

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  1. #1
    Member aratron's Avatar
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    Pocket Chronometer

    I often see in literatures the term "pocket chronometer". But I do not see much description regarding these highly sought after pieces. What is pocket chronometer exactly?

    With railroad standard of the yesteryears or modern day COSC, there are certain accuracy standard to meet, isochronism, position timing .. etc. Is it the same way with pocket chronometers?

    I see many are English in origin, so I am assuming in the early 1800s the English lever escapement was used. The escapement teeth were known to be extreme prone to damages and if made earlier, verge escapement were the standard ... which were even worst time keepers.

    I am very interested to learn a bit more about these curiosities.
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  2. #2
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    Re: Pocket Chronometer

    Well, I'll get the ball rolling. "Chronometer" was originally a generic term applied to any type of watch regardless of timekeeping accuracy. Similarly, "chronoscope" was the generic term for a watch used to measure short periods of time, ie, stopwatch. When the first timing tests were conducted by astronomical observatories, they applied the term "observatory chronometer" to indicate those that passed. This was following the precedent of marine chronometers, which also had to pass testing. Many manufacturers used the "chronometer" label to infer a quality that wasn't earned! It wasn't until COSC patented the term "chronometer" in 1973 that the word took on the meaning we understand today. I'm really quite ignorant of the English pieces but Radger's recent thread has been very enlightening.
    Tick Talk says, "A watch in the hand is worth two on the wrist"

  3. #3
    Member aratron's Avatar
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    Re: Pocket Chronometer

    Thanks for the insight.

    Interesting, this puzzling question came exactly from astronomical events. My local NAWCC meeting this week. We were watching presentation regarding the passing of Venus and the timing instrument used for these events the past 400 years. Many scientist used multiple clocks and pocket chronometer if they were in remote locations. Hence my question.

    One of the instrument they used was the "chronodrometer". I am assuming they are similar to the "chronoscope" you are referring to. Measuring only the passing period of time.

    If no common standard was used for these pocket chronometers, how would one identify a true pocket chronometer from standard pieces?
    Rolex Explorer II, Rolex Sub 16610, Rolex Speedking, Omega Planet Ocean, Omega 1930s Deco, Breitling Avenger, Girard-Perregaux Gyromatic, PAM 111, Movado WWII Bumper, Gruen 1930s Tonneau, Poljot Mechanical Alarm Caliber 2612, & Chrono 3133, Tudor Prince Oysterdate, Debaufre GMT Ocean 2893-2, Movado Kingmatic, Sea-gull 1963 Re-issue, Marathon GSAR, Tissot T-Touch, Steinhart SAWLE, Sea-gull ST8000SK Skeleton, Seiko 7002, Parnis Portuguese ST25, Orient Worldtimer, Orient Retro Camera, Orient Mako, Omega Speedmaster, Rolex Airking, Vostok Amphibia, Tudor Submariner, Sea-gull M199S, Seagull ST5 Export, Bulova Accutron Spaceview 214, Omega Constellation Pie Pan, Beijing Galaxy GMT

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    Re: Pocket Chronometer

    Quote Originally Posted by aratron View Post
    If no common standard was used for these pocket chronometers, how would one identify a true pocket chronometer from standard pieces?
    A compensated balance.
    A spring detent escapement.

  6. #5
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    Re: Pocket Chronometer

    Thanks, learned alot by reading up on spring detent escapement

    Pocket chronometers with detent escapement

    A compensated balance = bimetallic balance (notice how the two layers of metal used in the balance)



    A spring detent escapement.





    But would a bimetallic balance and spring detent escapement really be all that accurate vs say a railroad standard watch?

    Quote Originally Posted by trim View Post
    A compensated balance.
    A spring detent escapement.
    Rolex Explorer II, Rolex Sub 16610, Rolex Speedking, Omega Planet Ocean, Omega 1930s Deco, Breitling Avenger, Girard-Perregaux Gyromatic, PAM 111, Movado WWII Bumper, Gruen 1930s Tonneau, Poljot Mechanical Alarm Caliber 2612, & Chrono 3133, Tudor Prince Oysterdate, Debaufre GMT Ocean 2893-2, Movado Kingmatic, Sea-gull 1963 Re-issue, Marathon GSAR, Tissot T-Touch, Steinhart SAWLE, Sea-gull ST8000SK Skeleton, Seiko 7002, Parnis Portuguese ST25, Orient Worldtimer, Orient Retro Camera, Orient Mako, Omega Speedmaster, Rolex Airking, Vostok Amphibia, Tudor Submariner, Sea-gull M199S, Seagull ST5 Export, Bulova Accutron Spaceview 214, Omega Constellation Pie Pan, Beijing Galaxy GMT

  7. #6
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    Re: Pocket Chronometer

    Quote Originally Posted by aratron View Post
    Thanks, learned alot by reading up on spring detent escapement


    A spring detent escapement.
    Here is my take on the use of the term 'chronometer'

    Nowadays the term chronometer seems to apply any accurate watch, usualy adjusted to position.

    In the distant past, the term chronometer was used for a specific type of super accurate timepiece
    used by ships as a navigation aid. For 150 years until the advent of quartz accuracy these chronometers
    used the detent escapement of which there are two main types, the spring detent and the pivoted detent.

    The detent escapement, because it was used in ships chronometers was termed the 'chronometer escapement'
    and so for many years when the term 'chronometer' was used for a time piece it was expected to have the chronometer
    escapement.
    A pocket chronometer, until the late 19thC, would have a detent escapement and the reasons as to why these are
    predominantly English are many.
    The UK was, at these times, the predominant maritime nation accounting for a large percentage of the worlds shipping,
    and solving the 'longitude problem' was upermost in the early history of English horology. The best clock and watchmakers
    were producing chronometers for maritime use and so they would use their skills to produce pocket versions for selected
    clients, rich ship owners perhaps.

    In the accounts of Usher & Cole of 1870 a marine chronometer of best quality with rate, cost £21.00.
    A pocket chronometer in 18c gold case cost £35.00
    A Geneva watch from the same price list in 18c gold with gold dial and dome was £4.10s

    The cost to produce these early pocket chronometers and subsequent high price is why they are rare, the reason
    why they are English is because the best English watchmakers, drawing on their heritage, were competent
    to produce them.
    English chronometers used the spring detent escapement as used in marine chronometers. The detent escapement
    that you illustrate with your link is a later early French/Swiss? 20thC pivoted detent.

    The bottom illustration is a spring detent chronometer escapement.

    Anyways, as technology progressed and other escapements besides the 'chronometer escapement' became increasingly
    more accurate, they were entered for testing to prove that they could pass the testing that a 'chronometer' passed and
    so these to were called chronometers and assured a customer that his watch was supremely accurate.


    Quote Originally Posted by aratron View Post
    But would a bimetallic balance and spring detent escapement really be all that accurate vs say a railroad standard watch?
    It would be an unfair competition, the chronometer escapement is the most detached escapement of any and the most accurate.
    Even with an early bi-metalic balance with its inherent mid temp errors, a quality chronometer escapement of the spring detent type would
    beat a railroad watch for accuracy hands down.

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    Re: Pocket Chronometer

    Hi radger,

    Quote Originally Posted by radger View Post
    Even with an early bi-metalic balance with its inherent mid temp errors.....
    Even this problem was solved like in this movement:



    Here the compensation was linearized by splitting the usable temperature range into
    four sections. Further details here:
    bidfun-db Archive: Watch Movements: Ganthony 19'''

    Regards, Roland Ranfft

  9. #8
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    Re: Pocket Chronometer

    Thank you, Radger. For all the wonderful information.

    I was aware of the fact that English clock and watchmakers were at those times, the best in the world. The Swiss were in a sense, the Timex of its days. Making inexpensive pieces for the common folks.

    Sort of related to the pricing information you provided. According to book I am currently reading, an average grade jeweled Waltham pocket watch movement in 1890 was $10.89. (At those time movements were paired with cases at the jobber/ jeweler, so unfortunately, we could not compare it with your 1870s data.) But by 1899. The average grade Waltham movement has plummeted to just $4.49. Thanks to industrialization and automation of machineries. Waltham produced not only cheaper watches overall. But more accurate and precise timepieces on a mass scale.

    So an English marine chronometer of the best quality for £21.00, actually sounds very reasonable.

    My understanding is that detent escapement has some inherent problem. For one, they are none self starting. Besides that, if they are such good time keepers. I wonder why we do not see them being used more frequently? Expect for a few marketing gimmickry escapements or low cost pin levers, the short swiss lever escapement practically dominate the market after the 1900s. Even if pricing was a concern, if the detent escapement is so much better, I am certain more makers would have adopted this system. Why didn't they?











    Quote Originally Posted by radger View Post
    Here is my take on the use of the term 'chronometer'

    Nowadays the term chronometer seems to apply any accurate watch, usualy adjusted to position.

    In the distant past, the term chronometer was used for a specific type of super accurate timepiece
    used by ships as a navigation aid. For 150 years until the advent of quartz accuracy these chronometers
    used the detent escapement of which there are two main types, the spring detent and the pivoted detent.

    The detent escapement, because it was used in ships chronometers was termed the 'chronometer escapement'
    and so for many years when the term 'chronometer' was used for a time piece it was expected to have the chronometer
    escapement.
    A pocket chronometer, until the late 19thC, would have a detent escapement and the reasons as to why these are
    predominantly English are many.
    The UK was, at these times, the predominant maritime nation accounting for a large percentage of the worlds shipping,
    and solving the 'longitude problem' was upermost in the early history of English horology. The best clock and watchmakers
    were producing chronometers for maritime use and so they would use their skills to produce pocket versions for selected
    clients, rich ship owners perhaps.

    In the accounts of Usher & Cole of 1870 a marine chronometer of best quality with rate, cost £21.00.
    A pocket chronometer in 18c gold case cost £35.00
    A Geneva watch from the same price list in 18c gold with gold dial and dome was £4.10s

    The cost to produce these early pocket chronometers and subsequent high price is why they are rare, the reason
    why they are English is because the best English watchmakers, drawing on their heritage, were competent
    to produce them.
    English chronometers used the spring detent escapement as used in marine chronometers. The detent escapement
    that you illustrate with your link is a later early French/Swiss? 20thC pivoted detent.

    The bottom illustration is a spring detent chronometer escapement.

    Anyways, as technology progressed and other escapements besides the 'chronometer escapement' became increasingly
    more accurate, they were entered for testing to prove that they could pass the testing that a 'chronometer' passed and
    so these to were called chronometers and assured a customer that his watch was supremely accurate.




    It would be an unfair competition, the chronometer escapement is the most detached escapement of any and the most accurate.
    Even with an early bi-metalic balance with its inherent mid temp errors, a quality chronometer escapement of the spring detent type would
    beat a railroad watch for accuracy hands down.
    Rolex Explorer II, Rolex Sub 16610, Rolex Speedking, Omega Planet Ocean, Omega 1930s Deco, Breitling Avenger, Girard-Perregaux Gyromatic, PAM 111, Movado WWII Bumper, Gruen 1930s Tonneau, Poljot Mechanical Alarm Caliber 2612, & Chrono 3133, Tudor Prince Oysterdate, Debaufre GMT Ocean 2893-2, Movado Kingmatic, Sea-gull 1963 Re-issue, Marathon GSAR, Tissot T-Touch, Steinhart SAWLE, Sea-gull ST8000SK Skeleton, Seiko 7002, Parnis Portuguese ST25, Orient Worldtimer, Orient Retro Camera, Orient Mako, Omega Speedmaster, Rolex Airking, Vostok Amphibia, Tudor Submariner, Sea-gull M199S, Seagull ST5 Export, Bulova Accutron Spaceview 214, Omega Constellation Pie Pan, Beijing Galaxy GMT

  10. #9
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    Re: Pocket Chronometer

    Quote Originally Posted by aratron View Post
    Even if pricing was a concern, if the detent escapement is so much better, I am certain more makers would have adopted this system. Why didn't they?
    I guess one way of describing them is fragile. They needed exaggerated care, which does not make for a practical day to day watch for the average joe.

  11. #10
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    Re: Pocket Chronometer

    Quote Originally Posted by aratron View Post
    Thank you, Radger. For all the wonderful information.

    I was aware of the fact that English clock and watchmakers were at those times, the best in the world. The Swiss were in a sense, the Timex of its days. Making inexpensive pieces for the common folks.
    The Swiss produced their share of high grade watches mid 19thC but they couldn't produce a hairspring good enough for chronometer
    accuracy. If a Swiss maker wanted to produce a very accurate watch then he had to source a hairspring from the UK and, as you can imagine,
    he would have a job getting hold of the very best.

    Quote Originally Posted by aratron View Post
    Sort of related to the pricing information you provided. According to book I am currently reading, an average grade jeweled Waltham pocket watch movement in 1890 was $10.89. (At those time movements were paired with cases at the jobber/ jeweler, so unfortunately, we could not compare it with your 1870s data.) But by 1899. The average grade Waltham movement has plummeted to just $4.49. Thanks to industrialization and automation of machineries. Waltham produced not only cheaper watches overall. But more accurate and precise timepieces on a mass scale.

    So an English marine chronometer of the best quality for £21.00, actually sounds very reasonable.
    That's interesting pricing info for the Walthams, strangely enough I was trying to find cost new of
    a high grade Waltham from 1870 but no joy.

    £21.00 for a Marine chronometer might sound reasonable, but £35.00 for a pocket version!!! I'll bet
    that was a lot of money in 1870...in fact if I spend that kind of money on a watch today, then it
    better be good.


    Quote Originally Posted by aratron View Post

    My understanding is that detent escapement has some inherent problem. For one, they are none self starting. Besides that, if they are such good time keepers. I wonder why we do not see them being used more frequently? Expect for a few marketing gimmickry escapements or low cost pin levers, the short swiss lever escapement practically dominate the market after the 1900s. Even if pricing was a concern, if the detent escapement is so much better, I am certain more makers would have adopted this system. Why didn't they?
    I think that if they had been cheaper we would definately see a lot more pocket chronometers despite their inherent problems.

    As you say, they are not self starting and are also liable to 'set' (stop) if subjected to a sudden rotational force at the
    wrong time. As Trim says they had to be used carefully, you could get away them in a pocket watch but no chance in
    a wrist watch.
    It is an escapement that was always very labour intensive to produce and required high skills.
    It wasn't until the 20thC, that the U.S Hamilton managed to introduce machine process to the making of
    marine chronometers with any success.
    Last edited by radger; May 27th, 2011 at 15:26.

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