NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Th. Jefferson: stop wasting time on longitude
From: Frank Reed CT
Date: 2006 May 8, 00:16 -0500
Herbert, you wrote:
"Thanks for digging up this interesting letter."
You're welcome. I've been trying to find a copy of a letter to Jefferson by
a man named Consider Sterry who was a lunarian from southeastern Connecticut
(born in Stonington in the Palmer clan, he was a distant uncle of Capt.
Nathaniel Palmer, one of the discoverers of Antarctica). He, too, wrote Jefferson
about his new lunar method.
You wrote:
"There seems to have been no explicit instruction to Lewis as to the
method of establishing longitude. Did Jefferson leave this important
"detail" to Ellicott, the instructor? It's unlikely, when we consider
the minute details specified elsewhere in the instruction. How come it
was understood that chronometer plus lunars was the method to be relied
on? This seems rather strange at a time when the rest of the world had
long been using the Jupiter satellites for cartography and exploration
with demonstrable success. Why was this expedition not equipped with
suitable telescopes?"
Interesting point. I think part of the answer is that the early USA had many
knowledgeable sea-going navigators, but almost no astronomers.
And you wrote:
"My preferred answer until now was that Jefferson
knew that the trick to a successful exploit of satellite eclipses was
the availability of control observations. Since the U.S. did not have an
observatory of their own, Jefferson would have had to depend on
cooperation in Europe. Maybe he felt that the moon ephemeris in the N.A.
was sufficiently reliable to stand on its own, at least more so than
that of the Galilean satellites."
Of course, it would not have been difficult to set up a few make-shift
observatories for the duration of the expedition. Just one observer tasked to
watch the eclipses in each of the big cities (towns back then) Washington,
Philadelphia, New York, and Boston would have provided the necessary control
observations. They could have been equipped with telescopes identical to the one on
the expedition. Of course they would have needed proper skill in determining
local time simultaneously, but it seems it would not have been difficult.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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To , send email to NavList-@fer3.com
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From: Frank Reed CT
Date: 2006 May 8, 00:16 -0500
Herbert, you wrote:
"Thanks for digging up this interesting letter."
You're welcome. I've been trying to find a copy of a letter to Jefferson by
a man named Consider Sterry who was a lunarian from southeastern Connecticut
(born in Stonington in the Palmer clan, he was a distant uncle of Capt.
Nathaniel Palmer, one of the discoverers of Antarctica). He, too, wrote Jefferson
about his new lunar method.
You wrote:
"There seems to have been no explicit instruction to Lewis as to the
method of establishing longitude. Did Jefferson leave this important
"detail" to Ellicott, the instructor? It's unlikely, when we consider
the minute details specified elsewhere in the instruction. How come it
was understood that chronometer plus lunars was the method to be relied
on? This seems rather strange at a time when the rest of the world had
long been using the Jupiter satellites for cartography and exploration
with demonstrable success. Why was this expedition not equipped with
suitable telescopes?"
Interesting point. I think part of the answer is that the early USA had many
knowledgeable sea-going navigators, but almost no astronomers.
And you wrote:
"My preferred answer until now was that Jefferson
knew that the trick to a successful exploit of satellite eclipses was
the availability of control observations. Since the U.S. did not have an
observatory of their own, Jefferson would have had to depend on
cooperation in Europe. Maybe he felt that the moon ephemeris in the N.A.
was sufficiently reliable to stand on its own, at least more so than
that of the Galilean satellites."
Of course, it would not have been difficult to set up a few make-shift
observatories for the duration of the expedition. Just one observer tasked to
watch the eclipses in each of the big cities (towns back then) Washington,
Philadelphia, New York, and Boston would have provided the necessary control
observations. They could have been equipped with telescopes identical to the one on
the expedition. Of course they would have needed proper skill in determining
local time simultaneously, but it seems it would not have been difficult.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
