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: Graphical lunars
    From: Ken Muldrew
    Date: 2015 Feb 28, 16:21 -0700
    Francis, in 1790 George Margetts published Margetts' Longitude Tables which was a series of graphs that plotted the data in the Cambridge tables for lunar distances. Using this relatively small book one can easily clear a lunar in a few minutes that is accurate to a few seconds. I don't know why this method never took off but as early as 1790 the problem of clearing lunars had been rendered fast and simple to perform.

    On 2015-02-28, at 2:41 PM, Francis Upchurch wrote:

    Thanks Henry,

    This is really a very interesting historical  thing. Just found Dutton 1805 on Google who quotes the original Kelly method as described dating from 1797! So you could do lunar clearance in 1797 easily using these simple graphical techniques? Dutton claims they were accurate to 5’? Perhaps they were not? Otherwise why were they not taken up as routine?

    I shall look into it.

    Thanks again.


       \----------------------------+---------------------------------+   o_,
     O_/ \    Ken Muldrew, PhD      | Voice: (403) 226-6222           |   <\__/7
     <\__  \  Programming/Electrical| Cell:  (587) 890-3502           |     | /
      "\ L  | Arbourealis RDC, ltd. | kbmuldrew@gmail.com             |   / /
       <    +-----------------------+---------------------------------+ / /
                   Morning coffee recapitulate phylogeny               L/

    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