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    London symposium
    From: Wolfgang K�berer
    Date: 2006 Nov 24, 15:34 +0100

    Dear List,
    
    although Frank Reed has asked George about the London symposium, George and
    I agreed that I will report on it.
    
    The symposium was attended by list members George, Clive Sutherland,
    Geoffrey Kolbe and (new member) Nicolas de Hilster who brought along � as
    George mentioned today in his post � an instrument most of us (including me)
    never knew about: a spiegelboog. Nicolas has written a very interesting
    article on it in the Bulletin of the Scientific Instrument Society and will
    � I assume � provide a copy for anyone interested in it. Sadly I missed his
    demonstration of the use of the instrument during lunch break.
    
    The first two speakers talked about the problems of collecting post 1950
    navigational devices. In the extreme you would have to preserve the complete
    ship for integrated navigation systems if you wnt to show it later on, as
    parts of that system are on the top deck, others way down and the display is
    on the bridge. The museums try to overcome this problem by turning more to
    other kinds of documentation: collecting manuals, pictures and oral
    history/videos showing the actual use. Although this is not a problem of
    this list I still think these talks reflected the two sides of the coin that
    this list has to look at: the instruments, methods and procedures of
    navigation in a rather clinical, theoretical view on one hand and the actual
    practice of navigation on the other. The latter is � in my opinion � rather
    undervalued and I enjoy every contribution from someone like Henry Halboth
    who can tell about actual experience with the things that are discussed
    here.
    
    The next two talks dealt with well-known istruments: Guenther Oestmann
    reported on the reconstruction of a mariner�s astrolabe � and promptly drew
    the question from Alan Stimson in the audience whether he marked the
    instrument as a replica. Captain Malhao Pereira � former captain of the
    Portuguese sail training ship �Sagres� - reported on his experiments with
    replica astrolabes, cross staves and back staves and the accuracy
    attainable. He also talked about his research in the use of figures of
    magnetic declination as position indicator. His research in portuguese log
    books of the 17th and 18th century shows that declination values seem to
    have been used to estimate the distance westward of the Cape of Good Hope on
    voyages to the Far East. This coincides � by the way � with observations
    that Art Jonkers made in his book on magnetism in the age of sail.
    
    In the afternoon Jeremy Spencer from the National Museum of Australia
    presented his findings on Cook�s mapping methods on the coasts of New
    Zealand in 1769. From what I understood � and I admit that the Australian
    accent sometimes baffled me � he thinks that Cook was essentially making a
    running survey from aboard ship. After that Dr. Morrison-Low talked about
    the evidence on the navigational expertise of Alexander Selkirk � the real
    Robinson Crusoe. It isn�t much: just the tip of something that could have
    been a pair of compasses. As Selkirk was taken off the island alive one
    wouldn�t suspect that he left any navigational instrument of value, but the
    excavation of the site is still going on.
    
    Then Rob van Gent talked about the tobacco boxes of Pieter Holm and
    explained their use. In a worked example he showed that the tobacco box was
    able to predict the time of high water for the day of the symposium in
    London � though I am not sure whether he was just pulling our collective
    leg. Anita McConnell talked about the development and use of the marine
    barometer resulting in more efficient routeing of ships. Finally Robert
    Hicks talked about �Shadow theory and the evolution of altitude-measuring
    navigational instruments�. As far as I can understand he thinks that the
    development of altitude-measuring instruments in the West is owed to the
    works of Arab scientists on optics and shadow theory at the beginning of the
    last millenium. I was not quite able to see how much of this was pure
    conjecture based on the fact that some Western scientists (on land) most
    probably read books by Arab scientists. But there is obviously a lot still
    to be discovered about the exchange of nautical science between East and
    West.
    
    I was very pleased to meet not only George, Clive and Geoffrey in person,
    but also some people whose books are on my book shelf and who generously
    share their knowledge with others (like Alan Stimson, Guenther Oestmann, Rob
    van Gent, Otto van Poelje just to mention a few). For me it was a  special
    pleasure to meet again Willem M�rzer Bruijns which I last met 22 years ago
    at an exhibition on Lucas Jansz. Waghenaer in Enkhuizen and who is at the
    moment catalogueing the sextants, octants and circles in the NMM collection.
    As I sat on a table with him at dinner after the symposium I  did not take
    part in a lot in the fraternizing going on after the meeting. George will
    have to fill you in on that.
    
    The next morning George, Clive, Jeremy Spencer and I were allowed by Gloria
    Clifton and Willem to have a look at the instruments � especially circles -
    in the storage area of the NMM. George and Clive were able � as I understand
    - to falsify their notion that on circles the horizon mirror must get in the
    way at certain angles. It seems that these mirrors are so small � at least
    at the one I looked at � that you literally look around it. I myself had the
    opportunity to look at some calculating devices that I had never seen before
    and to look at the first � and probably only � circle made in the 21st
    century: �Clive Sutherland facit 2005�, a truly amazing piece of workmanship
    made from surprisingly simple materials. 
    
    On the whole it was really worth the trip.
    
    Wolfgang
    
    Dr. Wolfgang K�berer
    Wolfsgangstr. 92
    D-60322 Frankfurt am Main
    Tel: + 49 69 95520851
    Fax: + 49 69 558400
    e-mail: koeberer@navigationsgeschichte.de
    
    
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