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    Re: 100:1 ratio distance measurements
    From: Richard M Pisko
    Date: 2003 Apr 5, 01:24 -0700

    On Fri, 4 Apr 2003 17:39:07 -0800, Royer, Doug wrote:
    >measurement of the distance traversed (to the inch at longer ranges) while
    >moving the 10 mil angular distance is critical to keeping the measurement
    >consistant.I used a tripod and a plumb connected to the Bussol and measured
    >that distance from the start to the finish of the 10 mil angle.
    I asked about the standard Soviet artillery compasses,
    because I couldn't remember the figure before, and they are
    generally graduated to 6,000 mils in a circle according to a
    source I believe.  In other words, they essentially declared
    "Pi" was equal to an even "3" instead of 3.14159... the way
    it really is, or 3.200 the way the US military says it is.
    I have been making assumptions as to the amount of accuracy
    and portability you need, which may not be warranted.
    Rather than carry a tape and tripod to measure so
    accurately, walk through a 100mil arc and then the object
    will be away from you only ten times the distance you paced.
    Alternatively, if you can keep yourself on a straight course
    as on a road or with two bearing objects in line, the "broad
    and beam" angles of 45 degrees and 90 degrees to the third
    object with the unknown distance is probably easiest.  This
    is just a special case of the "double angle" problem.  Walk
    along a course "A-B" until the object "C" is at an angle of
    45 degrees off to the right (or left) front.  Start counting
    the paces while still heading along course "A-B" until "C"
    is off to the side at 90 degrees.  Then "C" will be as far
    away from you as the length of the leg you measured.
    All of this should be explained with diagrams in a book of
    coastal navigation, along with how to use the sextant on its
    side to get the angles more accurately than possible with a
    hand compass.  A cheap plastic sextant is not that heavy to
    carry with you while hiking, and is a lot of fun.
    It does not replace a map and compass, just makes (for
    example) planting and finding a cache a lot more accurate
    using at least three permanent natural reference objects not
    on a circle with your cache location.  These can be hundreds
    of yards apart.
    An old survey text with references to plane tables and
    mapping will make the methods more clear.
    The most difficult job of locating yourself is with the
    stars, sun and moon as your only guides; then you also need
    accurate instruments, timepieces, and tables.
    Perhaps the easiest is with a good orienteering map of the
    area, with land forms such that you can recognize where you
    are without even a compass.
    Richard ...

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