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Alex E, you wrote:
"Probably, if I were on your place, I'd follow  Frank's advise
and try to sell it on the same e-bay. (And recover at least a  part of the
loss). "

That advice was in a test message to "NavList". I don't think GH has  signed
up though most everyone else has.

And:
"But if you prefer to experiment with it
(which does not exclude the  selling option!),
you may try to determine the index correction by  carefully
observing star distances at say 10 or 15 degrees, where the arc  is
usable, and then use it for the Lunars. But not for distances  to
lighthouses."

Unless I mis-read his note, GH already got his money  back from the seller
when he went to pick up the instrument. I was simply  proposing a 'hypothetical'
and actually I assumed you would reply since that's  exactly the problem
you've got, too, though on a smaller scale.

In a  real sense, a table of arc errors is a table of index corrections as a
function  of angle. The important difference from the standard index
correction is that  arc error is not usually adjustable. So if you had a sextant like
this, if you  adjust the index mirror, you would need to re-measure the arc
error at one  specific angle. All the values at other angles should offset by the
same  amount.

-FER
42.0N 87.7W, or 41.4N  72.1W.
www.HistoricalAtlas.com/lunars

   

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