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: Today's octant sights - Back Sights
    From: Jeremy C
    Date: 2010 Mar 26, 20:46 EDT
    My Cassens and Plath Horizon Ultra sextant has such a pad as well for writing down sight data.  I have never used it.
    In a message dated 3/19/2010 2:22:48 A.M. Bangladesh Standard Time, FrankReed@HistoricalAtlas.com writes:

    Brad, you wrote:
    "It does seem technically possible and the existence of octants with a back sight feature confirms that (why add a feature that cannot ever be used)."

    The answer to this question is... drum roll please... "marketing". :-) People will pay money for what they can be convinced they need, not that they ever get around to using it! But mostly I would say that it's design inertia. It seems like every octant has that little chip of ivory on the back that was used as their version of a "post-it note" --a little spot where you could record sight data. But I've never seen a sextant with anything even remotely similar (I'm sure that some existed, just in very small numbers). And nearly every octant I've looked at up close has a substantial knob on the back so that the horizon mirror could be rotated to null out the index error. Sextants have various small screws or tiny knobs that might just barely be adjusted by hand but never with the intent of easy adjustment. Index error was to be measured, not nulled in sextants. Some of this is just evidence of the different original functions of the instruments. Sextants were developed *specifically* for shooting lunars with several design details that we retain today that are only there because they originally made sense for lunars. But a lot of it really has to be attributed to design inertia. Octant design stabilized with that ivory chip on the back. The back sight option was dropped somewhat before that stabilization.

    And no, my octant can't do back sights unfortunately...


    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    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