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    Re: Time and N.A.
    From: Steven Wepster
    Date: 2001 Jul 13, 9:52 AM

    Herbert Prinz wrote:
    
    > George Huxtable wrote:
    >
    > > However, I have since found that the lunar distance predictions in the
    > > Nautical Almanac switched from apparent time to mean time somewhere in the
    > > early 1800s.
    >
    > Not just the lunar distances, but the argument of the entire ephemerides used
    > to be apparent time up to the early 19th century. (An interesting exception are
    > the eclipses of the satellites of Jupiter, which were tabulated in mean time.
    > E.g. in Blunt's edition of  Nautical Almanac and Astronomical Ephemeris for
    > 1819.)
    
    I take the switch from apparent to mean time as an indication that mechanical
    devices were taking over as time keepers from the heavens. Well, of course we tried
    (and still) to keep some kind of relation between the clocks and the heavens. But
    basically when most practitioners switch over from one system to another, in a
    relatively short time span, something must have changed in their attitude towards
    time. Any views on this?
    
    _Steven.
    

       
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