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    Re: What is this on this sextant
    From: David Pike
    Date: 2016 Mar 16, 14:00 -0700

    Brad Morris you wrote: Hello David  I've always had a great deal of curiosity about the Countinho Sextant.  Thank you for that diagram.  It explains the optical path using the auxiliary mirror quite plainly.  The bubble in the single spirit level is reflected off of the aux mirror.  Does the smaller horizontal aperture provide an unreflected, direct path to that same bubble in the same spirit level?   Or is there an additional spirit level not shown in the diagram?  Thanks! Brad

    Hello Brad.  I must admit I hadn’t considered that the lateral view might be of the same spirit level as you suggest.  As the altitude measuring level is a lengthwise tube in the direction of viewing, I think not. 
    I just checked Ifland to make sure.  The diagram (fig 172 below) in Peter Ifland’s book shows a ‘Hohenlibelle’ (high dragonfly ???? according to Google Translate) and a separate ‘Querlibelle’ (transverse level).  Fig 171 (below) also mentions two levels.  DaveP 



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