NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
London symposium
From: Wolfgang K�berer
Date: 2006 Nov 24, 15:34 +0100
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 --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---