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    Re: Children's land-locked "Sextant"
    From: Bill Noyce
    Date: 2007 Nov 27, 10:46 -0500

    This may not give the level of precision you're looking for, but it's
    simple and easy for kids to understand:  Make a quadrant out of
    cardboard.  Print the protractor with a laser printer, either directly
    onto light cardboard, or onto paper that you glue to heavier
    cardboard.  Make sure the zero is parallel to one edge of the
    cardboard.  Cut around the arc so you have a quarter-circle, or a
    half-circle, or something in between.  Poke a tiny hole exactly at the
    vertex, and insert a thread.  Tape it in place on the back, and tie a
    weight (I used washers or nuts) so the thread hangs taut just below
    the arc.  Tape a drinking straw along the edge of the cardboard for a
    sight, so it is supported by the edge like this:  O==  To sight stars,
    you look through the straw with one eye, and around it with the other,
    and place the star at the center of the circle.  Rock the quadrant
    until the stationary thread just grazes the cardboard, pinch it in
    place, then read it.  You should be able to read to 15' or better with
    a reasonable-sized scale, though your sights will likely have more
    scatter than that.  For the sun, don't look through the straw --
    instead, watch the quadrant's shadow, and point the straw at the sun
    until its shadow becomes an "O".  Again take care that the quadrant is
    in the vertical plane, and pinch the thread.  (This measures to the
    center of the sun, not to either limb.) You should check each quadrant
    for index error -- assuming your printer is properly adjusted, and the
    thread pivots in the center of the arc, other errors should be
    negligible.  Good luck!
        -- Bill
    On 11/27/07, Isonomia  wrote:
    > I'm camping next summer with a load of 11year old kids and wanted to
    > do some celestrial navigation and plot a position to within
    > 10-20miles.
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