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Alex wrote-

| Yesterday, I tried a back sight of the Sun for the first time.
| My pocket sextant has an unusually long scale up to 150d.
| The Sun was at 45d. What I discovered is that my hair
| on the top of my head obscure the Sun somewhat...
| because my pocket sextant is very small, so that the index mirror
| is too close to my face.
| (So I had to wet and comb my hair). The sight was within 1'
| as it almost always happens with my pocket sextant, which reads
| to 1'.
| 45 degrees is probably the lowest altitude that I can measure with
| a back sight with this sextant.

Comment from George-

A trick to minimise this effect is to turn your head to one side, so
that the sextant mirror is trying to look past your ear, rather than
over the top of your head. That depends a bit on your skull shape; the
"dolicephalic index", I think, beloved of ethnologists. And, of
course, on how far your ear sticks out.

contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.


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