"Professor Young's Gravity Escapement"

Discussion in 'Clock Construction' started by MTROMAN, Mar 9, 2014.

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  1. MTROMAN

    MTROMAN Registered User

    Mar 5, 2014
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    Ann Arbor, MI
    Hi,

    Perhaps this is the right forum for this question:

    In the old literature (late 19th century, early 20th century), there are occasional references to "Professor Young's gravity escapement." Does anyone know for sure precisely what this is referring to? I am familiar with Denison's gravity escapement (as in the one at Trinity college and so many tower clocks), and I was wondering how different or similar Young's gravity escapement may be. Perhaps Denison's and Young's are one in the same, with Young's being the former name, since I don't see it used in more modern texts. Anyone have an illustration or description of the Young gravity escapement?

    Thanks,
    Mike
     
  2. tok-tokkie

    tok-tokkie Registered User

    Nov 25, 2010
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    I doubt if the Denison Gravity Escape could have been called Young's Gravity Escape previously.

    There is a complication because Denison had 3 names during his lifetime. Beckett, Denison & Grimthorpe http://en.wikipedia.org/wiki/Edmund_Beckett,_1st_Baron_Grimthorpe

    His escape of 1851 came directly after Bloxam's Gravity Escape and he discusses the Bloxam escape in his book about clocks & bells available from Google & Gutenberg http://www.gutenberg.org/ebooks/17576 I have it as a pdf & Young is not mentioned in it.

    In writing this reply I came across the Google copy of

    Big Ben: the Great Clock and the Bells at the Palace of Westminster

    By Chris McKay
    which gives a pretty detailed account of the development of Denison's gravity escape. It has no mention of Young - but some pages are not available to viewers outside the USA.
     
  3. Dick C

    Dick C Registered User

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    Here is a couple of references that might add to the discussion. If I read these correctly, Professor Young was an astronomer in Cornell University around 1883 or so.
    Evidently in his lab there was a gravity escapement clock.
    Please let me know what you think. When you read these documents, do searches for YOUNG, for ESCAPEMENT, etc. in order to narrow down having to read the complete documents.

    http://books.google.com/books?id=BLsCAAAAIAAJ&pg=PA540&lpg=PA540&dq=%22Professor+Young's+gravity+escapement%22&source=bl&ots=GADKoIMBm3&sig=e4-ererCy6qA9WAohJragKV3XHA&hl=en&sa=X&ei=JOcdU-L0KcXR2AWNz4DIAw&ved=0CCoQ6AEwAQ#v:^nepage&q=%22Professor%20Young's%20gravity%20escapement%22&f=false


    http://archive.org/stream/cu31924031322104/cu31924031322104_djvu.txt
     
  4. MTROMAN

    MTROMAN Registered User

    Mar 5, 2014
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    Thanks for the links. I do believe the Professor Young in question is likely the Astronomer Charles Augustus Young (1834-1908),mentioned in these texts. I believe he was a professor at Dartmouth and later Princeton, and he was evidently well known enough to be referred as simply Professor Young in texts discussing other Universities, like Cornell. He seems to have been an expert on the Sun as well as an early eclipse chaser. I think I'll likely find at least a description of his escapement by looking through his papers, but if someone beats me to it, please share your findings.

    Thanks!
    -mtr
     
  5. Dick C

    Dick C Registered User

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    Thanks for the link to Dartmouth and Princeton....following this up look at Page 229 of this reference:

    http://adsabs.harvard.edu/full/1908PA.....16..218P

    It appears that he started the design at Dartmouth and finished it at Princeton....for telescopes.
     
  6. Dick C

    Dick C Registered User

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  7. MTROMAN

    MTROMAN Registered User

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    Hmm.. that last reference is proving difficult to locate...
     
  8. mackerm

    mackerm New Member

    May 16, 2010
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  9. tok-tokkie

    tok-tokkie Registered User

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    mackerm, many thanks for that link. I have made a gravity escape and was delighted to read that article as it has some excellent quotes - a piece with blue marking alongside in particular.
    As a side not I note that you have been a member since 2010 but this was your 1st post. You save your comments for when they count! (said with respect & amusement.)
     
  10. MTROMAN

    MTROMAN Registered User

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    Excellent. Thanks for the helpful link! It would be neat to find a photo of an actual specimen, but I gather not many were ever constructed.

    Best,
    Mike
     
  11. Vickie Williams

    Vickie Williams New Member

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    My name is Vickie Williams I work in the Copy Department of the Cheshire County Registry of Deeds in Keene New Hampshire. My work # is 603-355-3001. I actually have a plan of Professor Youngs Gravity Escapement directions included from 1877
     
  12. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    I find it interesting the arguments of the author's arguments about
    "center of oscillation" that Mackerm posted. I do know what it refers
    to but believe his understanding of the issue is incorrect.
    Not to draw the thread off subject, if someone close to Vickie could
    get a photo copy of the document, that would be great.
    Tinker Dwight
     
  13. scottmiami

    scottmiami Registered User

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    Vickie, thank you very much for taking the time to register to reply to this thread with your wonderful find!

    If it is at all possible, it would be fantastic if you are able to scan or take pictures & upload them here for historical purposes, and to be able to share it with the rest of us here trying to save what information we can on this part of history.

    Tinker, I think after 2 years, it's perfectly reasonable to go off thread, particularly for such a good reason.

    Cheers!
    Scott
     
  14. Tinker Dwight

    Tinker Dwight Registered User

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    #14 Tinker Dwight, Jul 1, 2016
    Last edited: Jul 1, 2016
    On an object, there are two centers. One is the center
    of mass and the other is the center of inertia.
    This is often called the center of oscillation.
    Imagine a rod balanced with two weights. One
    weight is 2 lb while the other is one lb. They balance
    such that one is 1 foot away while the other is 2 feet,
    from the balance point, or center of gravity.
    Now if one pushes at the center of gravity, the longer
    end will tend to stay still, causing the rod to rotate.
    This is because the longer end has more moment of inertia.
    It is 1*2*2 where the other end is 1*1*2.
    Where the two moments balance out is the center of oscillation.
    The thinking is that if the two were at the same point, it
    would make a better oscillator.
    Actually one would want it to be slightly above the center
    of mass such that the pivot point would be stationary while
    the bob end moved. This way there would be minimum side
    thrust on the suspension.
    Tinker Dwight
     
  15. tok-tokkie

    tok-tokkie Registered User

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    Thank you for that explanation of the difference between CoG & CoO. I have read several discussions about it but never understood it properly.
     
  16. Tinker Dwight

    Tinker Dwight Registered User

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    It is also often refer to is the difference between static
    balance and dynamic balance.
    The center of oscillation is an issue for things that are changing
    velocity ( like a pendulum ).
    The flipped pendulums used to measure gravity would have
    its center of oscillation right at the pivot point not currently
    being used, as the pivot, at the bob end. This is why the length between
    the pivots exactly matched the simple pendulum equation.
    One could then time such a pendulum and determine g at
    your location to an accurate level.
    I'm not sure what doing this has to do with making an accurate
    time pendulum.
    I would think you'd want to keep it the CoO some place above the
    CoM so that the pivot wouldn't be taking all the side thrust of
    the rotational inertia of the bob and rod.
    One would want it to be such that if one was to push on the
    CoM in a circular path, the pivot point would stay stationary
    as the bob rotated around it.
    The fellow in the article seemed to imply that it would be better
    if it were at the bob, exactly as was the case of the double
    ended pendulums.
    That would put all the rotational mass of the bob as a side
    thrust on the pivot:???:?
    Tinker Dwight
     
  17. Tinker Dwight

    Tinker Dwight Registered User

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    Tok, for testing your pendulum, hold it in between your fingers,
    at the balance point, push it towards and away from your
    self. If it had a good CoO, the pivot point would stay
    stationary.
    If it moved with your motion or backwards, it would indicate
    not having at the optimum CoO.
    Tinker Dwight
     

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