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Thanks Alexander

Quick question:

Does the ^ symbol represent multiplication?

I am having a bit of trouble following the sequence of calculations in the
formula.

Any chance of your scanning in that particular page and sending to me?

I've always wanted a copy of Chauvenet but the $300 plus price tag deters
me.

cheers,

Robert
----- Original Message -----
From: "Alexandre E Eremenko" 
To: 
Sent: Monday, April 17, 2006 2:21 PM
Subject: Re: Error of Perpendicularity


> Dear Robert,
> The only book I know that contains a COMPLETE
> theory of sextant is Chauvenet. (I am sure that there
> are others, but this is really complete, very concise,
> and written in good English:-)
>
> In particular, on p. 115 (vol. 2) the following formula
> is derived:
> Err=-2 L^2 sin1" tan(h/4),
> where Err is the resulting error, in seconds
> L is the deviation of your mirror from
> perpendicularity (in seconds) and h the angle you measure.
>
> In more modern notation this becomes:
> Err=-0.00057 L^2 tan(h/4)
> where both Err and L are in minutes now.
>
> For example, if L=5'
> Then Err=0.008 or 05", which is completely negligible.
>
> Now, according to SNO manual, you can adjust this mirror
> (using special factory-supplied visors in place of dominoes)
>
> That's why visual adjustment (without dominoes) is OK too.
> Two years ago there was a large discussion on the list about
> how exactly to do this adjustment, and the general conclusion
> was that dominoes (or visors) are only recommended for sextants
> with front-silvered index mirros.
> For back silvered mirrors, the usual eye method is OK.
>
> Alex
>

   

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