Chronometry: Dent marine chronometer

Discussion in 'Chronometers' started by Michael J Delaney, Jul 31, 2017.

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  1. Michael J Delaney

    Michael J Delaney Registered User
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    I have just acquired a dent 2 day chronometer about 1847. It looks good seems to run well and is nice and clean, no damage to the balance spring, but it looses 3 seconds an hour. Should I leave it as is, or try and find a man who can
    have a go at rating it? I don't suppose it will ever be in a ship again. It would be nice to have your comments...
    Regards, Michael Delaney.
     
  2. MartyR

    MartyR Super Moderator
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    Photos would be nice :) And it would be helpful to know the serial number :D

    If you intend to run it all, it sounds as though your chronometer might need a complete clean and overhaul in addition to being rated. I believe that might cost a lot of money, and maybe some members here might be able togive you a clue.

    Your decision depends largely on how you feel about it ... and how much money you want to spend.
     
  3. gmorse

    gmorse Registered User
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    Hi Michael,

    I don't recommend letting anyone 'have a go' at this; it needs a skilled person with experience of these instruments.

    Regards,

    Graham
     
  4. Marco C.

    Marco C. Registered User

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    If it has been cleaned and overhauled recently, you should be able to regulate it yourself. I did this with my McGregor, which was running 7/8 seconds late per day and is now running about 1.5 seconds late. I followed the instructions given in two books, "The Mariner's Chronometer" by W.J. Morris and "The Marine Chronometer" by J. Croning. To speed up the chronometer you should turn the timing screws on the balance wheel clockwise. Turn them very, very little, just a few degrees, because the regulation is extremely sensitive. And of course turn both screw exactly the same, to preserve the balance poise.

    Of course it is better to have this done by an experienced person, if you have one at hand!

    Marco
     
  5. Snapper

    Snapper Registered User

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    Hi Michael,
    I too have a Dent chronometer (amongst others). Unless you are very confident working with clocks I would council against a DIY job. It is true that these instruments are not cheap to service but the price of the job could treble should you be unfortunate enough to cause damage. If you are UK based there are two rstorers I am aware of:

    http://marinechronometers.co.uk/profile.html

    and

    http://www.chronometers.biz/

    I haven't used either yet but I have an Eiffe chronometer that at some stage will have to go to one or other of these chaps. (the second reference is the author of the book mentioned above).

    As already stated above you will need to find someone with experience as they are very specialised. Let us know how you get on.
     
  6. gmorse

    gmorse Registered User
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    And the first reference is Roy Harris, who is Master of the Worshipful Company of Clockmakers this year.
     
  7. Michael J Delaney

    Michael J Delaney Registered User
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    #7 Michael J Delaney, Aug 2, 2017
    Last edited by a moderator: Oct 8, 2017
    Dent No 2044, just taken some photos. Don't know where it has been, but No 1978 has spent time in the University of Aberdeen and at sea during the last war. Antiquarian Horology March 2013. Having read up about rating and looked at it running, I have decided to leave well alone.
    So I will now try to find something about it's history. Regards, Michael Delaney.

    View attachment 249407 View attachment 352328 View attachment 352326 View attachment 352324 View attachment 352323 View attachment 352329 View attachment 352327 View attachment 352325 View attachment 352322
     
  8. Michael J Delaney

    Michael J Delaney Registered User
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    Thanks for all your replies, Regards, Michael Delaney.
     
  9. Michael J Delaney

    Michael J Delaney Registered User
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    Didn't realise the first lot of photos had been sent...
     
  10. Tom McIntyre

    Tom McIntyre Technical Admin
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    I will hide the extra post and I applaud your decision. Before I read it, I had intended to say it should be left alone if you were not intending to keep it running. If it were to be kept running, it could probably be cleaned and oiled at a relatively modest cost.
     
  11. MartyR

    MartyR Super Moderator
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    Great photos, Michael :coolsign:

    Mercer's book on Dent contains a list of Dent chronometers used on Admiralty ships. That list consists of extracts from the ledgers of the Royal Greenwich Observatory (now part of the Royal Museums Greenwich) and I assume the list shows all such Dents. #2044 is not included. That suggests to me that #2044 was not purchased by the Admiralty. One entry helps to date your chronometer - #2035 was purchased by the Admiralty on August 9th 1848. Of course that purchase may have been made some time (even years) after the chronometer was made.

    In a different section of the book, Mercer states that chronometer #1504 to #2375 were made between 1840 and 1853. That gives an average production rate of 62 chronometers per year, and that would date #2044 to about 1848, which ties in very well with the same date given for #2035.

    So taking both piece of information into account, I think a date between 1846-8 would be right for your piece.

    It is astonishing to note how well these marine chronometers survived. #2140 was made in about 1861 and continued in active Royal Navy service until about 1930, and you have quoted #1978 which must have been made in about 1845 which was in active service during the Second World War! Especially when you consider the conditions in which they were used, these marine chronometers were a tribute to the skill of the craftsmen who made them.

    When you find out more about it, please do post some further information here :)
     
  12. burt

    burt Registered User
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    #12 burt, Aug 4, 2017
    Last edited: Aug 4, 2017
    The United States Naval Observatory seemed to be a big fan of the Dent chronometers as they purchased quite a few (without actually counting) only behind the Negus Brothers and Parkinson & Frodsham in numbers. I don't think they purchased 2044 as it doesn't appear on the list I was privileged to view. In my experience I've concluded many chronometers were regulated to commercial service and that unfortunately makes researching their history nearly impossible. One exception I encountered was the Mercer that I wrote the story of on the Mississippi Shipping Company "The Delta Line".

    I think Marty's pretty close with his estimate of its age (or build date) as the box certainly is of a early style chronometer of that time period.
     
  13. Michael J Delaney

    Michael J Delaney Registered User
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    where have my photos gone?
     
  14. novicetimekeeper

    novicetimekeeper Registered User
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    They still exist, they have had a few difficulties with the transfer to a new board.
     
  15. Michael J Delaney

    Michael J Delaney Registered User
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    Just thought I would send the photos again, Michael Delaney.

    DSC06944.JPG DSC06950.JPG DSC06938.JPG DSC06948.JPG DSC06943.JPG DSC06946.JPG DSC06949.JPG DSC06947.JPG
     
    musicguy likes this.
  16. Tom McIntyre

    Tom McIntyre Technical Admin
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    Thanks Michael. If the image project goes as planned the two sets of files will be merged so long as you loaded the same pictures.
     
  17. novicetimekeeper

    novicetimekeeper Registered User
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    Looks wonderful, I can see why people like chronometers. I think I read he submitted one in the 50s to the Royal observatory some time in the 1820s. One went with the beagle in 1831 and that was number 633. He died in the early 1850s before completing the great clock, yours is one from the last years before his death.
     
  18. gmorse

    gmorse Registered User
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    Hi Nick,

    The best part is if you can see the escapement on one that's running.

    Regards,

    Graham
     
  19. musicguy

    musicguy Registered User
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    This is a great photo, it really is a nice looking chronometer.
    277830-704e5e91ab96c2ac55f154b1cade07b5.jpg


    Rob
     
  20. novicetimekeeper

    novicetimekeeper Registered User
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    Not sure I will ever afford one Graham, they go for more than I would have to pay for a half decent bracket clock.
     
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