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    Re: Lunar distance accuracy
    From: Wolfgang K�berer
    Date: 2007 Oct 27, 19:10 +0200

    George
    
    The Whipple Museum of the History of Science in Cambridge
    
    (I most now be out of favour in that reputable institution having relocated
    it to that other dreadful place)
    
    possesses 2 sextants on pillar stands according to J.A. Bennett's "Catalogue
    3: Astronomy and navigation": Accession numbers 1295 (Troughton c. 1795,
    pillar frame) and 821 (Ramsden c. 1795, double frame). That confirms my
    suspicion that there are "pillar sextants" on pillars.
    They also have reflecting circles on pillar stands (accession number 2123,
    Troughton c. 1805 and accession number 1079, Troughton c. 1810).
    
    I have already mentioned the instrument in the Science Museum.
    
    Hill and Paget-Tomlinson, "Instruments of Navigation", LOndon 1958,p. 39,
    mention a sextant stand in the NMM (Shelf mark S. 65). The shelf mark must
    have been changed in the meantime; Gloria Clifton should know.
    
    There are two more sextants on pillars in the "Museo Naval" in Madrid (No.
    inventario 1251 and 1322) according to L�pez Calderon, Cat�logo de la
    secci�n de instrumentos n�uticos y cient�ficos del Museo Naval de Madrid,
    Madrid 1996.
    
    I suspect that there are some more in other European collections. I'll keep
    you posted.
    
    -----Urspr�ngliche Nachricht-----
    Von: NavList@fer3.com [mailto:NavList@fer3.com]Im
    Auftrag von George Huxtable
    Gesendet: Donnerstag, 25. Oktober 2007 14:30
    An: NavList@fer3.com
    Betreff: [NavList 3576] Re: AW: [NavList 3563] Re: Lunar distance
    accuracy
    
    
    
    Wolfgang K�berer wrote-
    
    
    Two local museums (The Whipple museum for the History of science in Oxford,
    UK, and the National Maritime Museum in Greenwich,UK) list sextants mounted
    on pillars among the objects they possess. They are not "pillar sextants" of
    the double frame type, but clearly not for use on board. So it seems they
    are a special type intended for surveying on land.
    
    and added later-
    
    White himself uses the term "pillar sextant". But that doesn't necessarily
    mean a sextant mounted on a pillar: He said it was a Troughton sextant of
    the beginning of (his) century (i.e. the 19th). As Troughton is said to have
    invented the "pillar sextant" (double frame sextant) in 1788 it is possible
    that White was writing about such an instrument.
    
    And there is a "pillar sextant" on a pillar in another local museum, the
    Science museum in London, UK. Have a look at their web site:
    
    http://www.sciencemuseum.org.uk/objects/astronomy/1931-95.aspx
    
    ===================
    
    Thanks, Wolfgang, that's helpful. I now think it likely that White was
    indeed referring to the handheld double-frame sextant.
    
    Just a Minor niggle. The Whipple museum is in Cambridge, not Oxford, and in
    view of the long-held enmity between those two institutions, it's important
    to decide which is which. I am aware of the instrument at the Oxford museum;
    is there one also in Cambridge?
    
    George.
    
    contact George Huxtable at george---.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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