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The inverting scope is used for all day time observations, for example for Sun altitudes
of Sun-Moon distances of for measuring angles between the  objects on the shore, or for use
of the sextant as distance meter.

The purpose of wires is double.
They help you to hold the objects near the center of the field of view,
and they are used for collimation check (and adjustment if it is adjustable on this sextant).

For some aplications it is useful to measure and record the "distance" between these wires.
That is the angle between directions to the objects which match the wires in your field of view.

Alex. 
________________________________________
From: NavList@fer3.com [NavList@fer3.com] on behalf of Jerry Gorman [NoReply_Gorman@fer3.com]
Sent: Sunday, November 16, 2014 10:56 PM
To: eremenko@math.purdue.edu
Subject: [NavList] Kelvin Hughes Sextant

Hi As a yachtsman new to astro nav, I acquired a Kelvin Hughes sextant serial 
no 50117, it's grey ex admiralty. In the box is a fairly large dia lens which 
is the one I use as well as a telescopic eyepiece with 2 changeable lenses 
one has a pair of parallel lines the other 2 pairs of lines at 90 degrees. 
These invert the image. What are they used for. Also I have 2 shaded what 
appear to be replacement lenses not screwed and don't appear to fit anywhere. 
Can anyone explain the purpose of these please  . Thanks Jerry Gorman




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