Chronometry: John Poole marine chronometer 3364

Discussion in 'Chronometers' started by MUN CHOR-WENG, Nov 4, 2015.

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  1. MUN CHOR-WENG

    MUN CHOR-WENG Registered User

    Sep 5, 2000
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    This John Poole marine chronometer # 3364 c 1865 is now housed in a later day box most probably by Thomas Mercer.

    IMG_1852.JPG IMG_1863.JPG IMG_1871.JPG

    IMG_1899.JPG IMG_1901.JPG IMG_1881.JPG

    Mun C W
     
  2. Ralph

    Ralph Registered User
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    Jan 22, 2002
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    Mun, your chronometer has Poole's auxiliary compensation for middle temperature error applied to the balance. Some of the better makers implemented it into their chronometers. Dent, Barraud and others among them.


    Ralph
     
  3. Tom McIntyre

    Tom McIntyre Technical Admin
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    Aug 24, 2000
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    I have a chronometer with Poole's auxiliary that is not nearly in as nice condition as this one. Mine does have the auxiliary noted on the dial.
    View attachment 278933
     
  4. MUN CHOR-WENG

    MUN CHOR-WENG Registered User

    Sep 5, 2000
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    #4 MUN CHOR-WENG, Nov 5, 2015
    Last edited: Nov 5, 2015
    In an article published in CLOCKS July 1984, Vaudrey Mercer investigates the errors that besets the makers of early chronometers and the diverse methods they use to overcome them. In the article John Poole's chronometer balance with auxiliary compensation was discussed. His balance prevents the rim from moving outwards to its fullest extent and hence it is suitable for exposure to extreme cold. His chronometers were much in use in the vessels sent to find the North West passage. This type of balance halves the middle temperature error and greatly reduces the error in low temperature.

    Mun C W
     

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  5. Ralph

    Ralph Registered User
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    #5 Ralph, Nov 5, 2015
    Last edited: Nov 5, 2015
    Mun,

    Here's another Poole, a little earlier than your's. It is serial number 3312. It started life in a brass bound rosewood box, that regretfully has lost the upper two tiers. It was my understanding the plate spotting on this one is actually associated with John Poole. I've seen the same decoration on other Poole chronometers. Naturally, chasing around the internet, I can't find any examples to support that claim.

    This one also has auxiliary compensation and it is not noted on the dial.

    IMG_6832.jpg IMG_6833.jpg IMG_6834.jpg

    Ralph
     
  6. Paul Regan

    Paul Regan Registered User

    Mar 4, 2003
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    Here is a close-up of the dameskeening on my Poole #1472.
     

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