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: Artificial Horizon
    From: Richard M Pisko
    Date: 2011 Jul 24, 20:16 -0600

    On Wed, 13 Jul 2011 06:08:37 -0600, G Becker 
    > The plane table is a lost art, what are you mapping? How are you
    > transferring the north information from the sextant to the location of
    > the table?
    I did not see an answer to your question, possibly because it was a
    private communication or possibly my server did not pick it up.
    At any rate, my best guess for the use of a sextant would be for
    determining differences of elevation between objects of known distance,
    although an Abney level would be more convenient.  For traditionalists,
    the Indian pattern Clinometer has an angle scale and a tangent scale.
    More accuracy, both in reading the vertical angles and in sighting the
    objects, may be had from various telescopic alidades, most of which will
    have tangent scales or Beaman stadia arc scales in addition to the
    vertical angle and accompanying vernier scales.
    The table may be roughly oriented by a compass and a line on the sheet
    pointing to magnetic north (allowing for magnetic variation), and more
    accurately by a Solar compass sheet, knowledge of Latitude and Longitude,
    and an accurate watch; but the table is most easily oriented by trial and
    error as a three point resection problem (if suitable known points are
    already plotted on the sheet).
    Richard . . .
    Using Opera since the"Dog" died

    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