Dear Heiner & all, Dials such as the one in Pompeii were more common in the Roman world than the obelisk-type dials, I think.
I have written a paper on the origin of the pole-style principle in the Bulletins of the Flemish and the Dutch Sundial Societies (2003-2004). My conclusion was that the pole-style appeared in the Western world around 1400 in Germany. Zinner found a manuscript dated 1430, giving instructions for laying out the hour lines of vertical pole-style dials. He also found a mention to a diptych dial from 1417. The oldest still surviving, dated pole-style dial appears to be the one at the church of Weissenfels (Germany, near Leipzig). With respect to a possible Arabic connection, Len Berggren (NASS Compendium June 2001) wrote: "By the end of the tenth century Muslim scientists had invented the polar dial, the equatorial dial, and the horizontal dial with the gnomon parallel to the polar axis", referring to studies by David King. The suggestion that the pole-style principle might have been imported in the West by returning crusaders was discussed and rejected by Karlheinz Schaldach in BSS Bulletin 1996 (3). Armillary-type astronomical instruments were used by the Greek already, such as Ptolemy (2nd c. AD). Armillary spheres, as navigational instruments, were the basis for the Portuguese maritime expansion in the 15th century, as was illustrated by Roger Bailey in a talk at the 2001 NASS conference. I have been unable to find when armillary spheres were first used specifically as clocks. Best regards, Frans W. Maes 53.1 N, 6.5 E www.fransmaes.nl/sundials/ ----- Original Message ----- From: "heiner thiessen" <[EMAIL PROTECTED]> To: "'Sundial Mailing List'" <sundial@rrz.uni-koeln.de> Sent: Wednesday, July 13, 2005 7:20 PM Subject: Armillary Dial After Roman dials with their vertical obelisk type gnomons, when did sundials with gnomons in parallel to the planet's axis first appear? I found an entry in the BSS Glossary 2000 for the introduction of an armillary dial in 1598 by Valentin Pini. Would he have been the first one to have installed a 'modern' dial? Is there a history of the development of the dial ? Best wishes Heiner Thiessen 51N 1W -
