Hello Sarah, The 2 threads or edges may be straight or curved and may have any orientation. As long as there are 2 shadows of which the intersectionpoint is used as the point where to read the dial I call the dial a bifilar dial. This is based on historical reasons as I wrote in another message.
The original idea by Micknik was a dial with equiangular hourlines. New ideas with one curved thread and one straight thread give dials with parallel datelines or with parallel hourlines. Many other ideas are just for fun to show what happens with the patterns. Theoretical it is possible to use 2 curved threads or edges, however I never saw such a dial. With 1 curved thread a number of examples may be found in literature and even there is an example with 2 cylinders as shadowcasters. Best wishes, Fer. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E ----- Original Message ----- From: Sarah Edmondson-Jones <[EMAIL PROTECTED]> To: <sundial@rrz.uni-koeln.de>; John Davis <[EMAIL PROTECTED]> Sent: Saturday, October 21, 2000 5:46 PM Subject: Re: Bifilar Again! > Hello John et al, > I'm still trying to come to grips with the possibilities that bifilar dials > offer. Is it necessary for the 'lines/wires/planes' that cast the shadow to > be parallel with the dial plate? > best wishes > Sarah Edmondson-Jones > >
