Next message: Bill: "Re: A few new questions"
contact George Huxtable at
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
----- Original Message -----
From: "Red" <>
To: <>
Sent: Sunday, May 14, 2006 7:19 PM
Subject: Re: [NAV-L] sextant calibration
| George, failing to use a zero-adjustment, after obtaining a sextant
that was
| designed and built and sold at extra cost in order to enable you to
make that
| adjustment, is certainly possible. You are right. And building one,
at
| unnecessary expense which places your product at a marketing
disadvantage, does
| not mean the user MUST use it. You're right again.
|
| But failing to use the device, which can and often will eliminate
one potential
| source of math error from your reductions, makes absolutely no sense
at all. It
| would be what I call "belligerent ignorance", taking pride in NOT
obtaining or
| using the information and resources that in this case are literally
at your
| fingertips.
|
| While you've got a sextant in your hands for the first time, and
presumably you
| are taking the time to check it for errors and adjust them out, you
would have
| to be a particularly stubborn old coot to refuse to use one of the
simplest and
| most obvious tools on it to remove one step from all subsequent
observations.
|
| I expect those people wouldn't bother using a sextant at all, when
they can
| simply look at their own feet and announce just as confidently "I am
HERE!"
|
| ----- Original Message -----
| From: "George Huxtable" <>
| To: <>
| Sent: Sunday, May 14, 2006 1:34 PM
| Subject: Re: sextant calibration
|
|
| > Red appeared to argue with my earlier statement-
| >
| > | "But one adjustment that does NOT EVER
| > | need to be made is the zeroing of index error, whatever it may
be."
| >
| > in writing
| >
| > | The Plath companies apparently disagree with you, George. Their
| > sextants are
| > | built with an extra wheel and scale to allow the user to zero
out
| > the index
| > | error. Would I do this every time? No, certainly not. But it is
| > something that a
| > | user certainly would do the first time they got the sextant, and
| > were trying to
| > | set up a baseline of adjustments on it, including the mirror
| > positions.
| > |
| > | More like, to quote Gilbert & Sullivan's Mikado, "Never? Well,
| > hardly ever!" <G>
| >
| > What I said was that the index error adjustment, to bring it to
zero,
| > does not ever need to be made, and that's a correct statement. The
| > fact that Plath have arranged things so that if you want to adjust
it,
| > it's easy to do so, does not invalidate what I said. That's not
the
| > only instrument for which such provision has been made. I remember
| > seeing an ebony octant, from the early 1800s, provided with a
| > lever-on-lever mechanism for fine-tweaking the angle of the
horizon
| > mirror, for just that purpose. It provided just the right
sensitivity
| > of adjustment, and stayed nicely put when you let it be.
| >
| > But just because you CAN make such an adjustment doesn't mean you
NEED
| > TO. When Red says it's something "a user would certainly do the
first
| > time", I wonder where he gets that certainty from.
| >
| > George.
| >
| > contact George Huxtable at
| > or at +44 1865 820222 (from UK, 01865 820222)
| > or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
| >
|
