At 04:03 AM 5/16/2007, fer de vries wrote: >So far as I know this time sytem isn't seen on any real sundial.
Planetary hours do appear on a fair number of renaissance sundials and astronomical compendia. They are usually given in the form of a table of information that assigns the ruling planet for each hour. This table is associated with a scale of unequal (or seasonal) hours. So despite the subtlety to which Drecker refers, it seems to me that most users of the planetary hours in practice used the durations of seasonal hours for their purposes. As for whether Sacrobosco saw a distinction, as Drecker claims, I would need to read Sacrobosco's words in context. It might be that by a strict (modern) definition there was a distinction, but that Sacrobosco and later scholars like Clavius did not recognize it or think it sufficiently important given the terms of precision in which they worked. In this, as in all things related to past dialling, we must be very careful not to apply modern expectations of precision to earlier works. Sara Sara Schechner, Ph.D. David P. Wheatland Curator Collection of Historical Scientific Instruments Department of the History of Science Harvard University, Science Center 251c Cambridge, MA 02138 Tel: 617-496-9542 Fax: 617-496-5932 --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
