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
    Re: Latitude and Longitude by "Noon Sun"
    From: Jim Thompson
    Date: 2005 Jun 6, 06:39 -0300

    > -----Original Message-----
    > From: Robert Eno
    >
    > An old friend of mine, who passed away a few years ago, and who was an
    > experienced navigator for over 60 years, once told me that the
    > noon sun shot
    > was overrated; that all you had to do was to take a few shots with an
    > interval of 2 - 3 hours then transfer one of the LOPs. Fred and a
    > number of
    > other list members seem to agree, and so too, do I.
    
    In Sumner's little pamphlet from the 1800's he showed how to do a celestial
    fix from two morning sun sights.  On Page 11 (reproduced in Peter Ifland's
    book):  "And likewise if two altitudes be observed, the times being noted by
    Chronometer, and the two lines, corresponding to the two altitudes, be
    projected as before, then both the true Latitude and the true Longitude is
    found at the intersection of the two projected lines."
    
    That, I think, was the recorded point of discovery of the celestial fix in
    human history.  His ship was becalmed, so that he had only moved about a
    mile between the two sights, while the sun had travelled further during the
    intervening hours, yielding crossing LOP's.
    
    (Michel Vanvaerenbergh and Peter Ifland. Line of Position Navigation: Sumner
    and Saint-Hilaire: the two pillars of modern Celestial Navigation. Unlimited
    Publishing LLC. Includes a reprint of the entire 1843 first edition of
    Sumner's book, and translations of two key articles by St Hilaire.)
    
    Jim Thompson
    jim3 at jimthompson dot net
    www.jimthompson.net
    --------------------
    Outgoing email scanned by Norton Antivirus
    
    
    

       
    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