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Subject: Re: Lunar stuff (was: Calculating accurate apparent-angles between stars)
From: William Allen (allen@XXX.XXX)
Date: Wed Jan 08 2003 - 15:35:11 EST
George,
I for one will be very appreciative of any work you can provide and I will
wait as long as it takes. I can only imagine how time consuming this must
be!
And I agree that we hope Bruce will take to heart the serious interest that
many of us having in not only using his book of tables but also
understanding the theory behind the tables.
As for the targetted lunar epoch, I would suggest that we aim for the heyday
of lunars, which might be just before chronometers become widely available
at reasonable prices. Would this be a period around 1800 to 1850? I'm not
as expert on this as many of the other members, but this is my first
thought. Without the benefit of the Cotter book, I am wondering what year
did Borda (and others) first publish his (their) methods?
Thanks for the reminder about the various Cotter books. I own the History
of the Sextant, but you are right, there are other navigation titles written
by this Cotter. I am trying to get the History of Nautical Navigation from
my library. The prices mentioned by other helpful members seem a bit steep.
Regards,
Bill
-----Original Message-----
From: Navigation Mailing List
[mailto:NAVIGATION-L@XXX.XXX]On Behalf Of George Huxtable
Sent: Wednesday, January 08, 2003 2:47 AM
To: NAVIGATION-L@XXX.XXX
Subject: Lunar stuff (was: Calculating accurate apparent-angles between
stars)
Bill Allen said. in a thread: Calculating accurate apparent-angles between
stars
>I have been silently following the lunar discussion with fascination for
the
>last year or so. You might say I am on the lunar-tic fringe.
It has surprised me how many listmembers with an interest in lunars have
bobbed up to the surface over the last year. It's been most gratifying.
>I agree with George and his assessment of our needs for some detail behind
>Bruce's tables (which I own and have used, but like many, I wish I knew the
>rationale for what I am doing).
I hope, and think, that Bruce is hearing these messages.
>Also, George, I really appreciate the write-ups you did explaining lunars.
>Am I correct that there are only 4 parts or have I missed number 5?
Thank you, Bill. You are quite correct, sorry to say. I would be deeply
embarrassed about the situation, if I were the embarrassable kind. It's
become a family joke, here.
>I don't know if you
>had given any thought to going back through these and making any additions
>or corrections that might apply.
Well, what's on the stocks just at the moment is a revision of part 4, in
particular that section that deals with the possibility of calculating
predicted altitudes of the Moon and other-body, instead of measuring their
altitudes. This is a point that I got quite wrong in the original message,
and have been steered in the right direction by helpful interventions from
listmembers, for which I am most grateful. I'm going to be off-watch, away
from this coming Saturday 11 Jan for about 6 weeks, and it's touch and go
whether I can complete this revision and get it out to the list before
then. I will if I can. The intention is to tie up the series in a final
message (or maybe two) after my return in late Feb. Whether this
good-intention prevails over other commitments and a certain natural
indolence, remains to be seen...
The aim then will be to tie together all the parts of a lunar observation,
up to deducing the longitude. One problem is this: lunars play no part in
present-day navigation, so anyone making lunar observations nowadays is, to
some extent at least, delving into the past. But what period in the past?
The historical aspect becomes important, because the details of nautical
tables, and indeed the way navigators have thought about their
position-finding, have changed very significantly over the years. To some
extent at least these changes will need to be reflected in the final part
(or parts) of my series about lunars, when it appears. The intention is
that it WILL appear, and I appreciate the occasional nudges from
listmembers such as Bill, encouraging me to finish the thing off.
=========================
Now for Cotter's book on "A history of Nautical Astronomy". Don't order the
wrong book: he wrote several others on nautical technology, including a
good one on "A history of the navigator's sextant". I am glad that my
listing of errors to be found in Nautical Astronomy hasn't put off
potential readers.
I bought my copy about 3 years ago, which had to come from the US, at about
$90, as I remember. I put it on the Abebooks waiting-list, where it
languished for about 3 months before a copy turned up. Don't give up; it's
worth waiting for, in spite of its defects.
========================
By the way-
We will be away in New Zealand, and this is the story behind it. I come
from a big family, the oldest of seven siblings, and my youngest sister Syl
is over 20 years younger than me. She has cohabited with her New Zealand
partner for 16 years, producing two now-teenage daughters. Now, for some
reason, they have decided to get married. Not one to rush into things, our
Syl. So a lot of Huxtables are travelling to Christchurch, and as the
bridegroom is also one of a large family, it's going to be a big and
enjoyable shindig.
Or it will be, if President Bush doesn't manage to set the world on fire in
the meantime.
George Huxtable.
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