Hi Patrick & all, More on Fer de Vries' point 3: the first analemma (EoT curve) on sundials.
Marinus Hagen wrote an extensive article on the sundials engraved by David Coster in the Bulletin of the Dutch Sundial Society (1982, XII, p. 553-588). His (tentative) conclusion is that the sundial with analemmas now in the Rijksmuseum is the world's first. Coster's birth date is uncertain; probably in the 1670's. The designer was either Nicolaas Cruquius (1678-1754) or Willem 's Gravesande (1688-1742). Both lived in London for a while, were members of the Royal Society, met Newton and knew about Flamsteed's EoT data. The sundial bears the coat-of arms of Count Unico Wilhelm van Wassenaer Obdam. Based on the art-historical details, the sundial should be made somewhere between 1719 and 1733. I do not know of a later article that pinpoints the date to 1719. Hagen quotes "Gnomonique" by G. Bigourdan (1922), who claims that Grandjean de Fouchy (1707-1788) would have invented the analemma, but who does not mention a date. Hagen writes that he could not find any article by Fouchy about the analemma in the journal of the Paris Academy of Sciences, of which Fouchy was secretary. So it would be interesting to know the source for the claim from Québec. To be continued? Regards, Frans Maes ----- Original Message ----- From: "Patrick Powers" <[EMAIL PROTECTED]> To: "SundialList" <[email protected]> Sent: Monday, October 17, 2005 5:21 PM Subject: Re: equation of time Message text written by "Frans W. Maes" >Much older is a very elaborate copper horizontal dial, engraved around 1730 by David Coster, now in the Rijksmuseum (Amsterdam-4 in the book, with picture). It has analemmas for all hours from 8 to 16.< Hi Frans, this gets more and more interesting! Thanks for that. Just whilst you must have been sending your reply to the list I was looking at the web site of La Commission des Cadrans solaires du Québec (URL: http://cadrans_solaires.scg.ulaval.ca/cadransolaire/toronto.html) which has even more references.... La CCSQ has the following text: "Our French tradition, by its numerous authors of Gnomonics (Deparcieux (1741); Rivard (1742); Delambre (1819); Gotteland and Camus (1993)), has established that the analemma was invented in 1730, by the French astronomer Grandjean de Fouchy . Is it the final argument? I doubt it very much... And I am not alone for doing so! Ms. Gotteland continues her researches on that topic, and she revealed, in 1993, that there was no evidence that Grandjean de Fouchy has ever published a paper about his "invention". More, Mr Hagen, from the Dutch Sundial Society, told her that he found three portable sundials, with an analemma, and all of them were made before 1730: - one armillary sphere on a painting from the Fine Arts Museum of Amsterdam; - one table sundial, in the Greenwich Maritime Museum; let's recall that its sundialist is Mr. Vogler, who deceased in 1725; - and one horizontal sundial, kept in the Rijksmuseum of Amsterdam, with analemmas on each line of the hours. That sundial was carved in 1719 by David Coster...(eleven years before the supposed invention of 1730) According to Ms. Gotteland, de Fouchy would have been the first one, in France, to use the analemma on his sundials, but he did not invent it!" I wonder if there are any other references? Patrick - -
