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Dan Allen wrote:

>Does anyone have any clever ideas about determining one's elevation above sea 
level using a sextant?  What if one knows one's
>latitude and longitude exactly -- would that help?
>
Assuming you have a good horizon, meaning you are on a mountain by the
sea, simply:

1. Determine a line of position using the usual sight reduction using a
zero dip, or for slightly increased accuracy an assumed dip.
2. Assuming everything else is exact, the amount by which your estimate
is off your actual position represents the error in dip.
3. dip = 0.9692 * sqrt(h) (h in feet), therefore h = (dip/.9692)^2

If you assume zero dip, there will be a slight error due to the
difference in refraction but it will be negligable, I wouldn't bother.

You only need one line of position because you already know your
position, but two will help verify your answer.  You could average the
two results.

Dov

   

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