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    Re: Emergency Meridian Altitude
    From: David C
    Date: 2016 Dec 9, 11:54 -0800

    Intuition told me that the longer the pole (not sure if it is called a gnomon) the less the effect of measurement errors. I decided that I could measure to an accuracy of 1mm. The base value is  height  370mm   length shadow 121mm.  If I change the height by 1mm the altitude changes by 2.6'. I then calculated the error for multiples of the base value.

    x1  2.6'

    x2  1.3'

    x3  0.9'

    x4  0.4'

    It seems the longer the better but........the longer the pole the bigger the error due to it not being vertical. I haven't worked that out yet. There must be an optimum pole height to minimise error.

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