NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Chronometer question.
From: George Huxtable
Date: 2006 May 13, 07:42 -0500
Greetings, NavList members, from George.
I'm after a bit of real help, to answer a silly question that has been
bugging me.
It comes from a log of a whaling voyage, to the Greenland sea, between
Spitzbergen and Greenland, in 1818.
It is really very simple.
Departing from Shetland, with its Northerly point in sight, at a
certain time-by-chronometer, an alt. of the Sun (supposing the N. end
of Shetland to lie in long. 38'W) gave the Chronometer slow of
Greenwich 3 minutes 39 seconds ...
However, even in British home waters, the less-frequented parts had
not all been well surveyed by 1818, and the charts carried may have
been somewhat defective. Anyway, a modern atlas puts the N end of
Shetland at about 0 deg 50' W, rather than 0 deg 38' W as had been
assumed; quite a difference.
In the light of that information, what should the chronometer error
have really been?
Of course, working out the AMOUNT of the necessary change is a rather
trivial exercise. What I find to be challenging is working out the
DIRECTION to apply that correction. Each time I sit down and work
through the logic of it, my brain gives me opposite results. It's
certainly not rocket-science, this one, but it's got me close to
banging my head on the wall.
Is anyone else prepared to have a shot at it? Really, there are only
two possible answers, so there's a 50% chance of being right just by
guesswork. That being so, as they say in the exams, extra marks will
be given for showing your working. That would certainly make it more
useful to me.
George.
contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
From: George Huxtable
Date: 2006 May 13, 07:42 -0500
Greetings, NavList members, from George.
I'm after a bit of real help, to answer a silly question that has been
bugging me.
It comes from a log of a whaling voyage, to the Greenland sea, between
Spitzbergen and Greenland, in 1818.
It is really very simple.
Departing from Shetland, with its Northerly point in sight, at a
certain time-by-chronometer, an alt. of the Sun (supposing the N. end
of Shetland to lie in long. 38'W) gave the Chronometer slow of
Greenwich 3 minutes 39 seconds ...
However, even in British home waters, the less-frequented parts had
not all been well surveyed by 1818, and the charts carried may have
been somewhat defective. Anyway, a modern atlas puts the N end of
Shetland at about 0 deg 50' W, rather than 0 deg 38' W as had been
assumed; quite a difference.
In the light of that information, what should the chronometer error
have really been?
Of course, working out the AMOUNT of the necessary change is a rather
trivial exercise. What I find to be challenging is working out the
DIRECTION to apply that correction. Each time I sit down and work
through the logic of it, my brain gives me opposite results. It's
certainly not rocket-science, this one, but it's got me close to
banging my head on the wall.
Is anyone else prepared to have a shot at it? Really, there are only
two possible answers, so there's a 50% chance of being right just by
guesswork. That being so, as they say in the exams, extra marks will
be given for showing your working. That would certainly make it more
useful to me.
George.
contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
