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    "Artificial Sights"
    From: Fred Hebard
    Date: 2003 Mar 20, 09:33 -0500

    There is a link to a riveting, first-hand account of undersea cable
    repair in the late 1800s at
    At the end of the link is a detailed description of using sun sights
    through an artificial horizon on land to synchronize the chronometers.
    The author mentions using a sextant stand, reading the sextant to the
    second, and the chronometer to the tenth of a second.
    I wonder what a sextant stand would look like, specifically the part
    that cradles the instrument; ie, how does one attach the sextant to the
    tripod.  I also wonder what sort of sextant would allow one to read to
    the nearest second.
    Regarding the method itself, it would seem to me that one would have to
    know one's longitude in order to solve for time.  The author mentions
    working "Observations for Time" on each of 20 or 30 observations to
    arrive at synchronization to the nearest tenth of a second for the
    These guys also seem to be working sights to the nearest tenth or fifth
    of a minute of arc, although I infer this from the story rather than
    reading it directly.  I would imagine such accuracy would be very
    helpful in finding cable 20,000 leagues under the sea.

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