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This is really a topic to be adressed by people who know a lot more about it 
than me ( Willem Mörzer Bruyns or Peter Ifland for instance). But going 
through the literature one can find that there are indeed quite a few early 
sextants with ebony frames:
The NMM possess a some (Nos. S. 42, S. 114, S. 142, S. 168; in: Hill/Paget 
Tomlinson, Instruments of Navigation, London 1958) of  English and French 
origin. So does the Peabody Museum in Salem (Nos. 104 and 106; in: 
Brewington, Navigating instruments, Salem 1963) and the Museo Naval in Madrid 
(Nos. I-42, I-43 and I-122; in: Garcia Franco, Instrumentos Nauticos en el 
Museo Naval, Madrid 1959).

Peter Ifland's "Taking the stars" also has several pictures of sextants with 
wooden frames (Figures 35, 39, 47, 77)

Finally Cotter (History of the sextant, p. 142) states:
"From the time of the introduction of the sextant instrument-makers bagn to 
produce instruments with metal frames. Up to about 1760 the frames of 
quadrants were made from a combination of wood, brass and iron...
Although reflecting instruments having brass frames were manufactured long 
before the dawn of the nineteenth century, metal frames were not common until 
the middle of that century".

That could and should be checked against the contemporary descriptions of 
instruments in trade catalogues and manuals, of
course.

Wolfgang

-----Ursprüngliche Nachricht-----
Von: NavList@fer3.com [mailto:NavList@fer3.com]Im
Auftrag von George Huxtable
Gesendet: Mittwoch, 9. Juli 2008 19:03
An: NavList@fer3.com
Betreff: [NavList 5764] Wooden sextants. was; [NavList 5753] More on
Lunars



Henry Halboth's thoughtful posting, [5753] in the thread "more on lunars" 
raises lots of stuff to ponder, but I will ask here about just one aspect; 
the question of wooden sextants. I've started a new threadname..

He wrote-

 "I also certainly cannot believe that some of the earlier instruments made 
of wood with ivory arcs, although works of art, could be relied on as 
respects accuracy over a wide range of condition to be met at sea."

Yes. They might have been well-calibrated when first made, but any wood, 
even ebony, shifts over time as its wood, and its joints, age. It's the 
long-term stability of a metal instrument that makes it worthwhile dividing 
it to great accuracy in the first place.

Henry continues- "Frank knows as well as I do that there were also wooden 
sextants manufactured – how many I don’t know, but enough have wound up in 
collections and museums to give us a good sample."

That's the bit that specially interests me here. I don't doubt that such 
wooden sextants were made; indeed, I've handled one. It was a particularly 
small instrument, which you might think of as a "ladies' sextant", or 
perhaps one intended for teaching small boys. Certainly, it didn't call for 
wooden construction in order to minimise weight, if it was intended for use 
by grown men!

The excess angle-capability of a sextant, above the 90 degrees of the 
quadrant / octant, was required only for measuring lunars, which called for 
high precision, to at least some extent incompatible with a wooden 
construction. So a wooden sextant was rather a contradiction. But how common 
were they, ever? How many have "turned up in collections and museums", as 
Henry claims?

Here we have to be rather careful. Sometimes, a quadrant / octant can be 
wrongly described or catalogued in a collection as a "sextant", even by an 
experienced curator. Not because he's got it wrong, but because "sextant" 
has become a generic, accepted name for all instruments of this family.

And if they do turn up in a museum, does that indicate how common they were, 
or (perhaps) how rare? Museums often like to show the unusual, rather than 
the commonplace.

Perhaps they were more common in American collections than in European ones. 
After all, American mariners' technology had a lot of catching-up to do, a 
history of having had to import precise instrumentation from Europe, and 
well-developed woodworking skills. Silvio Bedini has written some useful 
stuff about that, in "Thinkers and tinkers".

So, I would like some enlightenment, please. Were wooden-framed sextants 
indeed commonly used by American navigators, and are they commonly found in 
American museums today?

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.




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