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: Sextant accuracy and possibility of future improvement
    From: Brad Morris
    Date: 2016 Jul 20, 11:58 -0400
    A sextant is not just a hand held device, nor is it used solely to measure altitudes, further, it is not limited to use at sea.

    Attached, please find an image of a COUNTERPOISE SEXTANT STAND.  In the image, one can observe not only the stand but also the frame of the prismatic sextant.  This stand will also fit my Circle of Reflection (CoR).  Alas, I do not own the stand, as it was a very pricey attachment when initially offered in the late 1800's / early 1900's.  At the time, the stand listed for $198.50!! 

    Using this stand, the CoR or the Sextant could be held in any orientation, and adjusted just so, until the observation was complete.  A right angle prism attaches to the eye piece such that the observation can be made without contorting the body.  Thankfully, the right angle prism came with the CoR, not with the stand.

    The CoR is marked to only 10", but due to the dual index arm arrangement, the readings are averaged, yielding 5" resolution.  This particular CoR, by serial number, was used to survey the locations of important nautical landmarks for chart making.  Had there been better resolution at the time, the survey would have availed itself.  As it stands, the 5" resolution was utilized.



    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