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
    Index corr. for back sights
    From: Alexandre Eremenko
    Date: 2004 Nov 20, 15:16 -0500

    George,
    
    "The method hitherto practiced for adjusting that
    part of the instrument, by means of the opposite
    horisons at sea, has been attended with so many
    difficulties that it has scarce ever been used;
    for so little dependance could be made on the observations taken
    this way, that the best Hadley sextants made
    for the purposes of observing the distances of the Moon
    from the Sun or fixed stars, have been always made without
    the horizon
    glass for the back observation; for want of which,
    many valuable observations of the Sun and Moon have been
    lost, when their distance exceeded 120 degrees."
    
    This is from
    "A letter from Mr. Peter Dollond, to Nevil Maskelyne, FRS etc.
    read on March 29 1772
    (Trans Royal Soc., you said you have easy access to this).
    
    Alex.
    
    
    

       
    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