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    Re: Camel-train Navigation.
    From: Rodney Myrvaagnes
    Date: 2003 Nov 2, 20:21 -0500

    On Sun, 2 Nov 2003 17:35:39 +0000, George Huxtable wrote:
    >Rather to my surprise, even modern GPS and modern mapping resulted in
    >problems, in that several features recorded by the early explorers had
    >become corrupted, with their names for certain hills transferred in error
    >to other hills. Perhaps one shouldn't expect perfect maps in such a
    >seldom-visited land.
    This shouldn't be such a big surprise. GPS receivers come with a
    built-in chart datum list. Modern charts name the appropriate datum,
    but Capt Cook neglected to do so.
    No doubt the Admiralty charts in the Channel and surrounds have been
    refined to a fare-thee-well over the centuries, but I can find survey
    errors in modern charts of the Maine coast, based on Admiralty surveys
    in the 17th and 18th centuries.
    For a notorious modern survey error, for which Admiralty surveys bear
    no blame, recall the expensive grounding of the QE II off Cuttyhunk
    Island in Massachusetts a few years ago. The Coast Guard was in the
    process of surveying the bottom in 1939, and had a grid of
    rectangularly spaced soundings. WW2 interrupted, and charts used those
    soundings, with nothing between them, even though there was clearly an
    unlocated peak between some of them.
    I have saved my pre-QE II chart for historical reference. It makes an
    interesting comparison to the new one.
    Sorry for wandering, but this is important for anyone using a really
    tight navigation system like GPS.
    Rodney Myrvaagnes                     J36 Gjo/a
    "I met about a dozen people who voted for me, and generally I can't say I 
    really agree with their reasoning."
    Bernard Goetz, subway gunman

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