Next message: Frank Reed: "Re: Buying a sextant- a cautionary tale."
George,
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). 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.
Alex
P.S. I am in this star distance business for two years already,
and I find it extremelly tricky to measure well (that is to 0.1'-0.2')
But I am pretty confident now that as a result of my effort
I did find that my arc is bad on the interval 0-5d,
approximately. Unless it is something else that I don't understand.
A
On Mon, 1 May 2006, George Huxtable wrote:
> Alex wrote-
> | George,
> | In a previous message I suggested some alternative
> | to displacing the index method.
> | How large is the area on the arc that you cannot read?
>
> From 5 deg on the arc to 5 deg off the arc,
> the fine divisions were completely gone.
> Between 5 and 10 on the arc, they could be
> read against the Vernier with great difficulty.
>
> Do take account of the fact that a sextant may be used
> to measure lunar distances in the night, and small angles such as height
> of a
> lighthouse, for distance-off, in the daylight.
>
> George.
>
> ===============
>
> contact George Huxtable at
> or at +44 1865 820222 (from UK, 01865 820222)
> or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
>
