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Subject: Lewis and Clark Celestial Navigation Procedures
From: Arthur Pearson (arthurpearson@XXX.XXX)
Date: Sun Nov 24 2002 - 11:46:12 EST
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
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