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Ken has asked a very fair question, and I'll do what I can to answer his
challenge. But first, let me be clear that I'm not claiming that
navigators' logs will show a preponderance of star-Moon observations. Most
will be of Sun lunars, because that's the easier option. What I'm claiming
is that, at times when a lunar was desirable, and a Sun lunar was
unavailable, mariners were expected to be able to use a star; and did so.

Unfortunately, the two sets of ship's-logs, that I have recently studied in
detail, don't help.

One was of an arctic whaler who only ever took Sun lunars, because no stars
were ever visible in his Arctic summer whaling seasons.

The other was of Cook's transatlantic crossings over 1764 to 1767. Although
the new Nautical Almanac appeared in the last year of those voyages, making
lunars practicable for the ordinary mariner, Cook had not then learned to
use them. It was not until 1768, on his first circumnavigation in
Endeavour, that he learned the art from the astronomer Green.

So I took a look in the Beaglehole account of that voyage, which started
from Plymouth on 23 August 1768.. I will list the body used with the Moon,
when a lunar was recorded, on the first leg of the journey as far as Rio de
Janiero..
5 September. Sun
6 Sun
4 Oct. Sun
15 Sun
16 Sun
17 Sun
20 Sun
21 Sun
28 Arietis, Pollux
2 Nov Aldebaran, Sun
3 Sun
4 Sun
14 Arrived Rio

Perhaps Ken might object that these were atypical, being of a famous
navigator (though not so famous then) in a well-found research vessel, in
the process of being trained up by a professional astronomer. Which, if he
did, I couldn't deny. What we really need to compare is the log from a more
ordinary trading voyage, such as one of the thousands made by the East
India company somewhere round 1800. I don't have any such at hand, but will
see what I can find.

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: "Ken Muldrew" 
To: 
Sent: Friday, March 19, 2010 3:40 PM
Subject: [NavList] Re: {Spam?} Sobel and Longitude. was:: Re: David Thomson
and his lunar tables


| On 18 Mar 2010 at 23:38, George Huxtable wrote:
|
| >  But in the
| > lunar era, a conscientious navigator would take a lunar when
| > the opportunity arose, when the Moon was visible in a clear sky. It was
| > part of the "professional pride" that Henry has referred to.
|
| George,
| Do you have any historical evidence to support this claim? Although
| instructors of navigation may have wished for such zeal in their
students,
| without historical evidence, such as logbooks, one should be skeptical.
| The logbooks that Frank has studied, and written about here, provide a
| different view of how navigators depended on lunars in that era. It may
be
| that his sources (primarily American whalers) have a bias toward a
certain
| type of navigator, but anyone proposing that hypothesis is obligated to
| provide some evidence to support it. Frank's historical evidence from
| primary sources has to be considered a trump card in this debate until
| such time as other sources can be shown to contradict, or at least
temper,
| his conclusions.
|
| Ken Muldrew.
|
|
|

   

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