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

    ----- Original Message -----
    From: "George Huxtable" 
    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.
    > 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
    > 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
    > a photocopy from a photographic negative of that Patterson document. It
    > 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
    > lunars, and instead left them to be calculated at a later date. In that
    > 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.
    > ------------------------------

    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