Dear Fer de Vries, I can't begin to tell you how much I appreciate your sharing, via your homepage, the procedures for computing flat sundials. I have been wanting very much to know how you computed the lines generated by Zonwvlak, but I hadn't built up the courage to ask you for so much explaining. Now, suddenly the explanations appear. Thank you. You have given us a wonderful holiday present!
Best regards, Mac Oglesby
