November's Object - John Evan's Rolling Ball Clock

Discussion in 'National Watch and Clock Museum' started by Noel Poirier, Nov 2, 2012.

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  1. Noel Poirier

    Noel Poirier Registered User
    NAWCC Member

    Jul 30, 2007
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    Shelf Clock, c. 1885, John Evans. Two-day brass and steel time only movement. Fusee driven. Inclined brass plane underneath the movement has track for steel ball. As plane tips, escape wheel is released. Made by John Evans after the design of its inventor, Sir William Congreve. Three dials. Hours represented on left most dial, and seconds on the right. Central dial indicates minutes and is printed, "Sir William Congrieve [sic]. Inventor." Engraved on signature plate, "89 Mount St, J. Evans, Grosvenor Sq. W." Brass movement is mounted on square wood base with velvet-upholstered top. Glass cover over movement.

    See this clock in operation on Youtube
     

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  2. MartyR

    MartyR Moderator
    NAWCC Member

    Dec 16, 2008
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    One thing that always surprised me about these clocks is that the ball and the grooves in which it ran withstood the ravages of friction sufficiently to maintain (presumably) some acceptable level of accuracy over many years.

    Is there any measure of the degradation of accuracy over time, and what material did the ball/grooves need to be made of?
     

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