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    Re: The length of a meter, was:Timing Lunars with a Rock
    From: Jared Sherman
    Date: 2005 Jul 19, 15:51 -0400

     I think the key word is "theoretically".
    AS  I understand it, UTM is based on a perfect cylinder, a Mercator
    Projection, for the bulk of the world (outside the polar areas) and given
    that distorted projection, your theoretical conversion works perfectly well.
    But from the references online it seems that the system is NOT designed to
    be converted that way. Rather, the linear mileage (meterage?) is marked off
    on each topo quad, and you are supposed to either draw on the quad or use an
    overlay on it. The primary purpose is military, i.e. artillery, where maps
    will be distributed and the only question is how to tell the big guns
    exactly where you are on the map that you were given. UTM works very well
    for that, or for anything else where you are using paper quads.
    See http://erg.usgs.gov/isb/pubs/factsheets/fs07701.html
    and http://ask.usgs.gov/ where the USGS provides PHONE and email contacts
    for folks to ask questions.
    I know there are conversion utilities for computer use, but I suspect they
    are either referencing offset tables, or counting distance and accounting
    for the distorted globe. Not something you'd want to do by hand.
    I'll let you ask the prime authority directly--I know UTM has become popular
    with hikers, but I can work with degrees and have had no need or use for

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