Dear all, [EMAIL PROTECTED] wrote: > > It is true that the first mechanical clocks was on the towers around > the begin of the 1300. And the first vertical sundials with the polar > gnomon was done arond the first half of 1300. The interesting > articles of Curt Roslund in the BSS Bulletin, september 2005, pag. > 116-119, show the vertical sundial of Braunschweig Cathedral of 1346 > with the equal hour lines and a polar gnomon.
The 1346 dial now has a polar gnomon. As recent as 1964 there was no gnomon, merely a large hole (Zinner). It is not known, how the original gnomon was oriented. In my view, it is unlikely that it was a pole-style. The angles were laid out according to the 'Erfurt formula', as Zinner and Roslund point out. This rule does not say anything about the orientation of the gnomon. If it was intended to be pointing at the celestial pole, the formula would most probably have provided accurate instructions for that. To answer Roger's question: The dates of the 1334 and 1346 dials were deduced from the building history of the cathedral, assuming that they were laid out at the time of completion of the particular buttresses. Regards, Frans Maes --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
