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On Sun, 20 Feb 2005, Fred Hebard wrote:

> Alex,
>
> I couldn't find the accuracy of the C+P on their website, at
> ,

Neither did I. That's why I asked.

> I would expect something
> on the order of 0.5'
> to 1.5'.

Then I do much better with Davis/oil for $22, not counting oil.
Some mess and inconvenience this creates does not seem
to we $900 worth. (I'd rather buy another sextant:-)

> Most bubble sextants have
> accuracies in that range, usually
> around 1.0'.

You mean aircraft sextants?

> The Frieberger may be limited by the levels,
> so that more accurate
> levels would give a higher accuracy.
> I'm guessing here that the mirror
> itself is ground considerably flatter than 0.5'.

I hope it is ground considerably flatter:-)
The top of my balcony table ($40 in Wall mart,
surface area 7 sq feet) is probably ground flatter.
Again, for $900 they could use finer levels.
I see "transit instruments/theodolites" on the web that
have 1" precision. As these instruments are not reflecting ones,
(not relying on the natural horizon)
I assume their bubble levels have this precision too.

Alex.

   

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