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Thanks to Wolfgang, who really is a magnificent mine of information.

I can straighten it out a bit further, however.

Wolfgang wrote-

| The original astronomical observations, made in the course of a voyage
| towards the south pole, and round the world, ... in the years MDCCLXXII,
...
| MDCCLXXV, by William Wales, ... and Mr. William Bayly, ... Published by
| order of the Board of Longitude, ...Wales, William. - London 1777.
|
| This is about the first voyage and contains the observation that George
| mentioned.

But no: it was from Cook's second voyage, not the first.. And the
attachment, though named by Wolfgang "4 August 1777", actually related to 4
August 1773.

Neither Wales nor Bayly were on Cook's first voyage, on which the
astronomer was Green. Green died on the return journey, and left his papers
in considerable disorder. Quite long after, in 1777, Wales sorted them out,
and published them, with those of observations of other early navigators,
in-

"Astronomical observations, made in the voyages which were undertaken by
order of His present Majesty, for making discoveries in the southern
hemisphere, and successively performed by Commodore Byron, Captain Wallis,
Captain Carteret, and Captain Cook, ... Drawn up and published by order of
the Commissioners of Longitude, ... By William Wales, ... Illustrated with
maps of New Zealand and the eastern coast of New Holland, ..."


Like the others, this is in the ECST (Eighteenth century short title)
catalogue, which means it is available through an (academic?) library, but
not by you and me at home.

But thanks to Wolfgang, it's good to learn that the third voyage
(presumably because of the exploration of the Canadian West Coast) has been
made available to all by the Canadians. We should make the most of it.

=====================

That page, of Bayly's observations from "Adventure", kindly supplied by
Wolfgang, is of great interest, and repays a close look; not just for that
one extremely-large lunar distance of 155� 13' 7", which , you may note,
was arrived at by everaging no less than 8 lunar observations.

Of those 38 lunars, three exceeded 120�, for which the Almanac predictions
provided no help, and it was necessary to calculate the Moon's position
from  Mayer's ephemeris, a formidable task.

You can see that the preference was always for a Sun lunar, when that was
possible, and that extreme observation of 4 August was the first chance of
a Sun lunar as the Moon was starting to wane from the full. And previous to
that, near full, a couple of star lunars had been taken, with Antares. The
previous Sun lunar had been a last-ditch try at over 145�, four days
earlier. So, by using those back observations, Bayly had shortened, by
several days, the period around full moon over which star lunars were
normally the only possibility.

At the top of the page, soon after the previous full moon, star lunars were
being taken also. There's a dead-patch, after 12 July, when no lunars were
taken around new moon, until 25th, though we don't know whether those
time-limits were affected by weather. Interesting things happened on 27
July, when two Sun lunars were taken before sunset, and two different star
lunars after, providing remarkably consistent results. Presumably, those
stated longitudes came from the lunars rather than from the Arnold
chronometer. I wonder whether that may have been some sort of training
exercise for the midshipmen on board.

From that evidence, all the altitudes appear to have been observed rather
than calculated, and the star-moon altitudes can't all have been in
twilight, so somehow, trustworthy night-time altitudes were being taken
from a moonlit horizon.

Latitudes were not quoted for every day, so presumably, there were days
when the sun failed to appear at noon. But it can be seen that lunars were
being taken every day or night, sometimes more than once, whenever it was
possible to do so.

There's more to be got, out of such a page of observations, than from a
whole chapter in a navigational textbook. But it should be kept in mind
that this wasn't an ordinary vessel, manned by ordinary navigators. The two
vessels were  Royal Navy research ships, commissioned for the purpose,
provided with the very best navigational equipment that was obtainable,
with two professional astronomers from Greenwich.

Thanks to Wolfgang for supplying such stuff to work with. The
freely-available text of the third voyage should also provide useful
material, particulatly after the chronometers had failed

George.

contact George Huxtable, at  george@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: "Wolfgang K�berer" 
To: ; 
Sent: Sunday, March 28, 2010 4:22 PM
Subject: [NavList] AW: Re: AW: Sun Moon Lunars to 155 degrees


| Antoine,
|
| I got confused, so let me straighten it out:
|
| the book which you can download from
| http://www.archive.org/details/cihm_17414 is:
|
|
| The original astronomical observations made in the course of a voyage to
the
| Northern Pacific Ocean, for the discovery of a North East or North West
| passage : wherein the north west coast of America and north east coast of
| Asia were explored in His Majesty's ships the Resolution and Discovery,
in
| the years MDCCLXXVI, MDCCLXXVII, MDCCLXXVIII, MDCCLXXIX, and MDCCLXXX /
by
| Captain James Cooke [sic], ... and Lieutenant James King, and Mr. William
| Bayly, London 1782
|
| It is about the third voyage of Cook. I misidentified it in my first
post.
|
| The page I sent is taken from this:
|
| The original astronomical observations, made in the course of a voyage
| towards the south pole, and round the world, ... in the years MDCCLXXII,
...
| MDCCLXXV, by William Wales, ... and Mr. William Bayly, ... Published by
| order of the Board of Longitude, ...Wales, William. - London 1777.
|
| This is about the first voyage and contains the observation that George
| mentioned. A digitized version is in the 'Eighteen Century Collection on
| line' and can only be accessed through a library. Then you can download
it
| completely - though not for commercial purposes.
|
| Hope that helps
|
| Wolfgang
|

   

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