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    Re: iPhone as artificial horizon
    From: Paul Saffo
    Date: 2008 Sep 10, 10:36 -0700

    "iKamal"... I love it!
    On Sep 10, 3:49�am, frankr...@HistoricalAtlas.net wrote:
    > A simple app that could be written would measure the angular tilt of the
    > device and record it when the screen is tapped. One could then aim the
    > device at the Sun by minimizing its shadow, and then immediately read out
    > the altitude. As you say, these altitudes are only accurate to 30 minutes of
    > arc or maybe somewhat better, but you might still be able to extract some
    > useful navigational information out of it (and this would work even if the
    > device has no access to network information/cell phone capability). It might
    > make a very good digital compass...
    > There are off-the-shelf digital levels available that measure angles to
    > about +/-10 minutes of arc reliably (at 6' nominal precision). You could
    > stick a simple sighting tube on top of one and you have a digital "sextant"
    > in no time. But a device like this is not that useful for manual
    > observations. It abandons the most important trait of the sextant:
    > double-reflection. Without double-reflection, we're right back to the days
    > of the backstaff or the kamal, and shaky hands are the limiting factor in
    > taking sights. So I guess in the end, I would call a device like this a
    > "digital kamal" rather than a digital sextant.
    > �-FER
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