Hello Fer, Excuse me for my ignorance. Being a new member of NASS, going through the references in the Repository CD, I see references to a T. J. de Vries and to a F. J. de Vries. I take it that you are the F. J., who is the T. J. ?
I am very interested in sundials with uniform indications of time movement and was attracted to your Cycloid Polar design as well as the comment in Fred Sawyer's Equant article from T. J. de Vries on mapping the horizontal dial gnomon shadow crossings of a curve into uniformly spaced parallel lines. I've tried mapping the curvature of a gnomon to map the shadow of a vertical south dial into uniform parallel lines such as your cycloid unit at specific dates. The curves for several times of the year are so different that I've not yet been able to envision what a solid would look like for the whole year ( If there is one ).(For Local Mean Time) btw: Doesn't the equant curve shape remind you of a "Cardioid curve"? (The Cardioid being related to the cycloid by the moving circle being on a circle of equal size rather than a straight line.) Your software and other articles have also been very helpful and informative. I wish to thank you for your thoughts, information and the obvious time you have given. Thanks! Edley McKnight [43.126N 123.526W]
