NavList:

Hewitt Schlereth wrote-
"One of the good things about celestial is you can learn all you need to
know without going to sea - just ask Lewis or Clark."

Lewis and Clark may well be icons of American history, but they should not
be held up as examples of celestial navigation. They may have been
competent leaders of a military expedition into then-alien lands. Their
dead-reckoning along the river may have been workmanlike. But as celestial
navigators, they were inept.

It wasn't really their fault. Wich no experience of navigation between
them, Lewis was pitched into a crash-course on celestial navigation with
the astronomer Robert M Patterson, in Philadelphia, before the journey
started. He was provided with a handwritten document, Patterson's
"Astronomical Notebook", which he carried throughout the great journey. It
was not at all "user-friendly", and did not address the special
requirements of a land-navigator. I have made a transcript of its contents
available, with an explanatory commentary, at-
http://www.hux.me.uk/lewis01.htm

After leaving Philadelphia, Lewis had no other source of navigational
advice. When Clark joined, he was instructed by Lewis, so it was a case of
the blind leading the blind.

I have made a detailed analysis of the early part of their journey, in
http://www.hux.me.uk/lewis02.htm .
This covers their ascent of the Mississippi, from its junction with the
Ohio, near modern Cairo, to winter near its junction with the Missouri,
close to St Louis. From this point, the expedition proper commenced, up the
Missouri. So these were their days of self-learning about navigation, in
which they would make every conceivable blunder. Unfortunately few of those
errors were recognised, and most continued right through the voyage. As a
result, not one of their deduced positions was ever correct, and even
simple latitudes were grossly in error.

So, fine explorers they may have been, and they certainly made a momentous
journey. But Lewis and Clark should not be held up as exponents of
celestial navigation.

George

contact George Huxtable, at  george{at}hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

----- Original Message -----
From: "Hewitt Schlereth" <hhew36@gmail.com>
To: <NavList@fer3.com>
Sent: Saturday, September 18, 2010 6:04 PM
Subject: [NavList] Re: sextant practice and time keepers


| Good Afternoon, Alan -
|
| Well, welcome to a quaint old art. It's always heartening to see a new
mind
| engaged by it.
|
| I'm curious about the sextant you're using and what sight reduction
method.
|
| Also be interested  to know what general (landlocked) part of the world
you
| are in.  One of the good things about celestial is you can learn all you
| need to know without going to sea - just ask Lewis or Clark.
|
| Hewitt
|
| On Sat, Sep 18, 2010 at 12:46 PM, Alan <alan202@verizon.net> wrote:
|
| > For reasons unknown, during the last few years I became interested in
| > celestial navigation, strange as that might be, for I'm not a
| > boating/sailing type.
| >
| > In any case, getting "good" with a marine sextant requires practice
with
| > the thing, an activity that living inland makes difficult. A while
back,
| > looking though a Celestaire catalog, I came on the Davis Artificial
Horizon,
| > and purchased one. They also offer a Practice Bubble Horizon that
mounts on
| > the sextant. I have yet to obtain success with the latter, though he
former
| > works, assuming that one reads the brief instruction sheet that comes
with
| > it.
| >
| > Working against a Known Position (GPS coordinates), my calculated fix
| > (estimated position) often falls well within 5 NM of KP. Granted, I'm
not on
| > a small boat, bouncing all over the place, however granting that, one
can
| > get about as much practice as they can stand with the Davis Artificial
| > Horizon.
| >
| > As to time keepers, a while back I purchased a Casio G-Shock Atomic
Watch,
| > via Amazon. Paid about $50.00 for it. The thing is, and remains dead
nuts
| > on, as far as I can determine via checking with Official Time via
computer,
| > time data coming from The Naval Observatory.
| >
| > For the sake of clarity, aside from being, in a small way, a customer,
I
| > have no connection with either Celestaire or Casio.
| >
| >
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