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Subject: Accuracy of Lewis and Clark Observations
From: Paul Middents (pmiddents@XXX.XXX)
Date: Fri Jun 14 2002 - 18:46:50 EDT
I have just found a very interesting article which addresses Lewis and
Clark's observational methods: "The Accuracy of the Astronomical
Observations of Lewis and Clark", Richard S. Preston, Proceedings of the
American Philosophical Society, Vol 144, No. 2, June 2000
http://www.aps-pub.com/proceedings/jun00/Preston.pdf
I am still absorbing the details but in summary, Preston determines why
simultaneous altitudes were not measured in conjunction with the lunar
distances. These altitudes were to be calculated from an assumed
longitude and then used to clear the lunar distance of the effects of
refraction and parallax. He finds that this method as recommended by
Andrew Ellicott and Robert Patterson is technically correct. It should
yield reasonable results with a single iteration for most cases. Had
Lewis and Clark's results been calculated, Most would have been
reasonable.
He speculates why F.R. Hassler (Mathematics professor at West Point)
might have given up in despair when trying to calculate from Lewis and
Clark's data. I was most surprised to find out that the data had never
been computed.
Preston developed computer programs based on a method developed by
Robert Bergantino of Montana, to calculate positions and finds that
Lewis' data supports positions within about 30 minutes of arc in
longitude.
I find this article extremely interesting. It seems to solve a long
standing mystery concerning Lewis and Clark's methods and somewhat
vindicates their observational ability.
I have followed the thread between George Huxtable and Bruce Stark on
the question of calculated altitudes. Bruce is acknowledged by Preston
in the article so I know he is familiar with this. I find no other
reference to either Preston or Bergantino in the Navigation-L archives.
I would appreciate the opinion of the "lunarians" on this list of
Preston's work.
I would also like to express my appreciation and admiration for George
Huxtable's series, "About Lunars".
Paul Middents
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