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Ken Gebhart wrote-


>Re Mr. Piccer?s 5 min error.  Such an error with a plastic sextant is not
>unusual no matter how careful one is. As has been mentioned before,  the
>critical areas of a sextant are the pivot of the arm, and the worm screw of
>the micrometer.  Granted that plastic injected molding should yield
>identical parts, but the assembly is still done by hand.  Any variation in
>inserting the pivot, and glueing the holding cap on it could easily
>contribute to such an error.  Same goes for the worm screw.  Add in the many
>other sources of error that have been discussed earlier, and I am not
>surprised at all.

Because it's a measurement by reflection, to get a discrepancy of 5'
requires an error in sextant reading of 10'. Ken knows a lot more about
plastic sextants than I do, and I am not familiar with the Davis sextant
that was used. But I would be VERY surprised to detect an error of 10' in
my plastic Ebbco.

George.


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5HX, UK.

   

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