# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Sextant Vernier Scale (correction)
From: Gary LaPook
Date: 2012 Mar 9, 17:51 -0800
I meant the NINTH mark not the eleventh mark, see corrected text  below.

gl

--- On Fri, 3/9/12, Gary LaPook <garylapook---.net> wrote:

From: Gary LaPook <garylapook---.net>
Subject: [NavList] Re: Sextant Vernier Scale
To: NavList@fer3.com
Date: Friday, March 9, 2012, 5:40 PM

 You can prove it to yourself that this is a vernier that reads to 0.1'. Line up the upper mark, the one with the dot, with a mark on the drum. Now count down the marks on the drum and you will find that the tenth mark, the bottom line on the vernier, lines up with the NINTH mark on the drum. To show how this works turn the drum up slightly and the next mark on the drum will line up with the next mark on the vernier. continue slowly turning the drum and you will see that the marks line up consecutively on the drum and on the vernier. Then the last, the bottom, mark on the vernier lines up with a line on the drum you will see that the top mark, the one with the dot, on the vernier now lines up with the next mark on the drum.gl--- On Fri, 3/9/12, Scott wrote:From: Scott Subject: [NavList] Re: Sextant Vernier ScaleTo: NavList@fer3.comDate: Friday, March 9, 2012, 5:15 PMChris,I just noticed your recent post to NavList about my confusion with the Vernier Scale on a Cassens & Plath sextant from a few years ago.What works for me is using the line with the "solid dot" as the reference ZERO for the vernier scale.  I then use the rest of the marks on the scale as .1' ... I have used this with good results and this explains their error statement of .2' accuracy.  Best of luck with your Cassens and Plath Sextant ... I love mine.Scott OwenOn 2/27/2012 5:39 PM, Chris Collins wrote:> I have the same problem actually. Did you ever find the answer?> > Chris Collins> > [this message refers to NavList post 4495 which may be viewed here:> http://fer3.com/arc/m2.aspx/Sextant-Vernier-Scale-ScottOwen-feb-2008-g4495]> ----------------------------------------------------------------> NavList message boards and member settings: www.fer3.com/NavList> Members may optionally receive posts by email.> To cancel email delivery, send a message to NoMail[at]fer3.com> ----------------------------------------------------------------
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