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    Re: Cable Time
    From: Fred Hebard
    Date: 2003 Mar 23, 22:28 -0500

    I apologize if I'm repeating myself.  But it seems to me there is a
    circular argument going on here.
    The navigators in the story very clearly were determining the error in
    their chronometers by land observations of sun or stars.  There would
    be no need to do so if accurate time could be transmitted by cable.  So
    one concludes that accurate time could not be transmitted by cable, or
    was not transmitted very often.  (To do so, one would need to establish
    accurate time at the transmitting station.  If that station were
    located near the shore, and relayed signals from Paris or London by
    land-borne telegraph, then I expect that accurate signals could not be
    propagated to the station by land-borne telegraph, due to the time
    delays introduced by relays along the way).
    It would seem to me to be much easier to determine time at the
    transmitting station by observing the moons of Jupiter or some such, in
    place.  This also could be done at each cable station to determine
    longitude accurately.  Once the longitude of a station were known, one
    could determine the error of one's chronometers as described.  As
    George Huxtable describes, simple triangulation from the level spot to
    the benchmark spot could determine the location of the level spot, if
    the location of the level spot differed from that of the benchmark
    spot, which it might not.

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