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    Re: Early Land Navigation.
    From: Frank Reed
    Date: 2015 Feb 9, 14:31 -0800

    David Pike, you wondered:
    "What did you mean the sun is so low it makes the use of an artificial horizon impractical?"

    I believe he said that the Sun is so far south that it makes the use of an artificial horizon impractical. But you see... he is in the southern hemisphere, so a far southerly declination for the Sun actually implies that the Sun is too high for an artificial horizon. Assuming a sextant has a maximum practical angular measurement of 120° (some manage a bit more but we'll ignore that), that implies a maximum altitude of 60°. How did 19th century explorers/surveyors in Africa and Australia, for example, measure latitudes on land with a sextant when the Sun at noon was higher than 60 degrees?

    Frank Reed
    ReedNavigation.com
    Conanicut Island  USA
     

       
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