Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: F. Barker & Son Box Sextant
    From: Sean C
    Date: 2016 Apr 7, 06:11 -0700

    There is something amiss there.....

    -Geoffrey Kolbe

    Yes, but what? I actually just carefully separated the face plate which holds the working parts from the case by removing three tiny screws from the periphery of the case. I could see nothing wrong with either mirror (other than what appered to be some very minor, scattered pitting and a bit of frosting at the edges of the index mirror.) I don't believe there's anything wrong with the telescope since the direct images were not distorted. I even rotated the telescope in its retaining ring while I was looking through it and there was no change in the distortion.

    Before I removed the face plate, I thought maybe the retaining screw for one of the mirrors was too tight, perhaps causing the mirror to bow a little. But upon closer examination out of the case, I saw that the screws are pushing against a retaining clip, which in turn pushes against the edges of the mirror. (See attached drawing.) I didn't dare remove the mirrors from their mounts for fear of damaging them or otherwise screwing something up. So, I'm at a loss as to what could be causing the problem. Any ideas from our resident experts would be greatly appreciated.

    For now, it seems to be in good enough shape to do sun sights, at least.


    Sean C.


    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site