Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Advice on Box Sextant
    From: Geoffrey Kolbe
    Date: 2016 Mar 31, 12:54 +0100


    On 30 March 2016 at 16:28, Alexandre Eremenko <NoReply_Eremenko@fer3.com> wrote:

    I own a very similar sextant, but made by Troughton and Simms.
    It works remarkably well, much better than one can expect.
    ​That was my reaction too​. I bought mine after you had said how impressed you were with yours.
     
    The telescope is a Galileo one, and the telescope filter is lost.
    It has two index glass filters. The absence of the telescope filter
    prevents me from measuring Index error with the usual method using Sun.
    But all observations I took with it indicate that there is no perceptible
    index error.
    ​The side error and the ​index error can be removed using the little key, the top of which is the smaller of the two knurled knobs on the top
     
    In general, I find this telescope inconvenient (too small, too small field of view).
    For most observations I just do not use it. It does not seem to influence accuracy.
    
    The true purpose of Galileo telescope on a sextant is to collect more light
    in twilight observations. But this telescope has so small diameter that
    it is completely useless for this purpose.
    
    For sun observations is helps just a little.
    ​I figured as much. I contemplated making a small telescope for this instrument - but the sextant really is very small​ and making a usable telescope on a suitable scale seems a lot more effort than the return would justify. A small slip-in filter holder is another matter though..... I will give that some serious thought.

    Geoffrey Kolbe
       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    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