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D Walsen and I both found our way to the same US patent, and both posted it
as an attachment, so I will not do so again. But somehow, my text got
hopelessly garbled. I'm not sure how it happened, but here's the text part
again, with my apologies.

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

Bruce Hamilton asked-
"Can someone identify this

Anyone need something for their collection? What exactly is it?


http://cgi.ebay.ca/ASTRONOMIC-CALCULATOR-SEXTANT-theodolite_W0QQitemZ190265697439QQcmdZViewItem?hash=item190265697439&_trksid=p3286.c0.m14&_trkparms=72%3A1215%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318 
"

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

It's a Zerbee "Fix Finder".Perhaps it's THE Zerbee Fix Finder. described in
the US patent 2519532 , attached. It could be the prototype, perhaps the
one-and-only, because it's labelled serial number 1; the invention of LouisB
Zerbee, patent granted 1950. You can dial up the details in GooglePatents.

I've never seen one or even heard of it before. It claims to be able tosolve
one OR MORE spherical triangles, simultaneously, so could presumably result
in a fix from a pair of star altitudes. I admit to not having studied the
details of the patent in any detail. These things are written in a special
arcane language that seems intended to obscure more than it reveals.

It seems to be a development of the armillary sphere, an analogue
representation of the Earth and sky, allowing spherical triangles to be
solved. Such armillary spheres first appeared in China in the first-century
BC. The nearest thing to this device I've seen (in print) is the Mariner's
Calculator, in Janet Taylor's "Navigation simplified" of  1849, but that
could solve only one spherical triangle at a time.

But this one is FAR more sophisticated. Just look at the profusion of
arcscales, each fitted with its own micrometer readout. No expense has been
spared in its construction; which may be why it wasn't developed further. It
would be interesting to discover what accuracy was achievable.

It's the sort of instrument I would love to own. You could play with it for
hours. I expect it will fetch a lot more than the present bid, and should
really find a home in a museum. Perhaps a Museum of Complication, if such a
speciality exists.

contact George Huxtable, now 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.Navigation List
archive: www.fer3.com/arc


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