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Bruce Hamilton asked-

"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 inthe US 
patent 2519532 , attached. It could be the prototype, perhaps 
theone-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 
presumablyresult in a fix from a pair of star altitudes. I admit to not 
having studiedthe details of the patent in any detail. These things are 
written in aspecial arcane language that seems intended to obscure more than 
it reveals.It seems to be a development of the armillary sphere, an 
analoguerepresentation of the Earth and sky, allowing spherical triangles to 
besolved. Such armillary spheres first appeared in China in the 
first-centuryBC. The nearest thing to this device I've seen (in print) is the 
Mariner'sCalculator, in Janet Taylor's "Navigation simplified" of  1849, but 
thatcould 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 beenspared in its construction; 
which may be why it wasn't developed further. Itwould be interesting to 
discover what accuracy was achievable.It's the sort of instrument I would 
love to own. You could play with it forhours. I expect it will fetch a lot 
more than the present bid, and shouldreally find a home in a museum. Perhaps 
a Museum of Complication, if such aspeciality exists.George.contact George 
Huxtable, now at george@hux.me.ukor at +44 1865 820222 (from UK, 01865 
820222)or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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