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: The Observer’s Book on Astro-N avigation - Coutinho sextant
    From: David Pike
    Date: 2016 May 2, 14:41 -0700

    The diagram opposite page 187 of ‘Precision Astrolabe’ isn’t very clear.  The diagram on page 163 of ‘Taking the Stars’ is better, but it still doesn’t tell you everything.  I went to the British Library and photographed the pages of ‘Precision Astrolabe’ covering Figs 22 and 23.  These pages don’t seem to be available on-line. Unfortunately, I didn’t record the page number, but my photograph can be found here:
    http://fer3.com/arc/m2.aspx/What-this-this-sextant-DavidPike-mar-2016-g34846 .  Looking at it again, I can see that if I’d looked at it properly the first time, I wouldn’t have had to ask Bill the questions I did.  Presumably, you had to tilt the frame a fraction the get the body to appear on the natural horizon, in the centre, or in the bubble.  DaveP

    Look at page 187 of "Precision Astrolabe" that I previously posted.

    On Sat, 4/30/16, David Pike wrote: Subject: [NavList] Re: The Observer’s Book on Astro-Navigation - Coutinho sextant To: garylapook---.net Date: Saturday, April 30, 2016, 4:43 PM BillIt would be very useful if in addition to your other excellent photos you could get a photograph of the view of the bubbles down the eyepiece to supplement the diagrams on page 163 of 'Taking the Stars'.  Also 1, does the Coutinho require fiduciary marks for the longitudinal bubble, or is the radius of the level cunningly matched to something?  Also 2, how does the Coutinho allow for the fact that the body is focused at infinity, and the levels are about nine inches in front of the observer’s face?  DaveP

    View and reply to this message

    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