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    False Horizons
    From: Mike L
    Date: 2007 Nov 20, 03:43 -0800

    As a separate question to my other post, I want to use a sextant on
    land to demonstrate to children that you can locate your position with
    the sun.
    The obvious first problem is getting an accurate fix on the "horizon",
    and  the obvious answer (even without a book) was to use a reflection.
    All good in theory, but in practice it is full of problems.
    1.  there is the problem of keeping a bowl of water still with kids
    jumping up  and down,
    2. trying to get children to stay one position long  enough to keep
    the reflection in view
    3. using the filters makes it even worse because they can't see the
    bowl of water and  the sun's reflection is quite a bit darker.
    Eventually for my younger child  I tried setting up a plank in the
    garden and tying the sextant up with  string to give a level, but the
    darn sun moved so quick that it ran off the  end before I had a chance
    to set it up with any accuracy. I'd appreciate any ideas!
    Refraction errors on false horizons
    The great advantage with a false horizon for children (as opposed to
    the sea), is that there is no need to pay for icecreams! AKA, taking
    the children to the sea side - but  more importantly there is no need
    to know the size of the sun, the height of  the waves, the height of
    the person or anything else like that as they all  cancel out.
    The great disadvantage is that you still have refraction through the
    atmosphere (though not of the horizon!) and the only table I have
    doesn't  list refraction of the horizon separately from that of the
    direct view of  the sun so I would appreciate some information on this
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