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: Lewis and Clark Celestial Navigation Procedures
    From: Greg Boyles
    Date: 2002 Nov 24, 11:43 -0700

    unsubscribe
    ----- Original Message -----
    From: "George Huxtable" 
    To: 
    Sent: Sunday, November 24, 2002 11:31 AM
    Subject: Re: Lewis and Clark Celestial Navigation Procedures
    
    
    > Arthur Pearson asked about the lunar navigation of Lewis and Clark.
    >
    > A reference appeared recently on this list to a paper about Lewis and
    > Clark's navigation,  The paper was "The accuracy of the Astronomical
    > Observations of Lewis and Clark", by Richard S Preston, in Proceedings of
    > the American Philosophical society, vol 144, No 2, June 20000, pages 168.
    I
    > think it was available from a website but am sorry to say I have lost that
    > address. Arthur would find it a most interesting read.
    >
    > That paper referred to an Astronomy notebook kept by Lewis, which
    contained
    > instructions, in manuscript, written by the astronomer Robert M Patterson,
    > in the form of solutions to 5 "problems".
    >
    > I am most grateful to Bruce Stark (well known to this list), for sending
    me
    > a photocopy from a photographic negative of that Patterson document. It
    had
    > many flaws which made it difficult to read, but I have completed a
    > transcription to make it more readily understandable to the reader. I have
    > added a detailed commentary to explain aspects of the document to a modern
    > reader who is familiar with celestial navigation but unfamiliar with the
    > concepts and practices of the early 1800s.
    >
    > This has been written in two parts as two separate emails: the first
    > dealing with solutions to problems 1 to 3 and the second with problems 4
    > and 5, and both these documents need to be taken together. These are long
    > emails (and Lewis and Clark may be a minority interest) so I will not
    > burden the Nav-L list with them (but if anyone asks for them to be posted,
    > I will). Instead, if anyone interested contacts me off-list, I will be
    > happy to send a copy directly. If any readers would like to check this
    > stuff out and inform me of errors or flaws, that would be appreciated.
    >
    > Arhur says- I am particularly curious
    > >about how closely their methods conformed to our recent discussion, "Re:
    > >Use of Sun Sights for Local time, and Lunars for Longitude".
    > I can say that Patterson's writeup has helped me to understand how the
    > altitudes of the bodies involved in a lunar can be calculated rather than
    > measured.
    >
    > It seems that Lewis and Clark always omitted to measure altitudes for
    their
    > lunars, and instead left them to be calculated at a later date. In that
    way
    > they could avoid setting up a reflecting pool, which would otherwise have
    > been necessary for their lunars.
    >
    > It appears from the Preston paper that some of their latitude observations
    > were greatly in error, which might imply that their use of a reflecting
    > pool was somewhat error-prone. However, I have made no further
    > investigations of my own into the Lewis and Clark results, nor have I seen
    > the Ambrose book.
    >
    > George Huxtable
    >
    > ==================
    > Arthur Pearson said-
    >
    > >Ladies and Gentlemen:
    > >
    > >I am interested in learning more about Lewis and Clark's navigational
    > >procedures.  There has been some tangential mention on this list about
    > >their lunar methods of obtaining longitude. I am particularly curious
    > >about how closely their methods conformed to our recent discussion, "Re:
    > >Use of Sun Sights for Local time, and Lunars for Longitude". Stephen
    > >Ambrose's book "Undaunted Courage" provides glimpses into how they
    > >worked, including the following:
    > >*       In Philadelphia, 1803, Lewis acquired "A Practical Introduction
    > >to Spherics and Nautical Astronomy" and "The Nautical Almanac and
    > >Astronomical Ephemeris" as well as "tables for finding latitude and
    > >longitude" (p. 91).
    > >*       At one location along the Missouri, Lewis "measured the distance
    > >between the sun and the moon's nearest limb forty-eight times.. He
    > >faithfully recorded whatever he could whenever he could, leaving up to
    > >experts back east to work out the meaning of the figures" (p. 148).
    > >*       Ambrose states that "...he wrote a thousand-word description of
    > >the instruments he was using, how he was using them, what he was
    > >measuring, and so forth.  It seems Lewis wanted to be as sure as he
    > >could tat someone someday would take all his figures and make some sense
    > >of them."
    > >
    > >Has anyone on the list examined that thousand word description of how
    > >Lewis made his celestial observations?  Would the tables he acquired in
    > >Philadelphia have been Bowditch's recently published "New American
    > >Practical Navigator"? Is there an essay or paper anywhere on this topic
    > >of his celestial procedures? Any insight or direction to additional
    > >sources would be most welcome.
    > >
    > >Thanks,
    > >Arthur
    >
    > ------------------------------
    >
    > george---.u-net.com
    > George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    > Tel. 01865 820222 or (int.) +44 1865 820222.
    > ------------------------------
    >
    
    
    

       
    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