Hello again Patrick: you wrote: > >There will be a problem in mid winter as well as in mid summer. It will be >necessary to ensure that in mid winter when the sun is low and the shadow >point moves out, you can still see it and the observer can still draw an >imaginary line back to the dial's origin in order to estimate the time. >This will mean that an area just outside the normal circumference of the >dial may have to be as flat as the dial plate itself or that the dial plate >may have to designed to be bigger than would otherwise be necessary for an >horizontal dial. In this design you won't have the usual benefit of a >conventional horizontal dial of the shadow being formed from different >parts of the gnomon at different seasons....
YES! This is a very important detail that I must consider in the design of your horizontal "head nodus" sundial. Even though my(your) interactive head nodus horizontal dial will not have actual declination lines drawn on the face, I must to consider the winter and summer solstice dec lines in the design phase because these will tell me how far out the hour lines should extend. Unlike traditional monofilar horizontal dials which tell time from sunup to sundown, this dial will function like a horizontal dial with a perpendicular vertical gnomon. This means that the shadow of the head nodus will reach infinity at sunrise and sunset. These dials can not tell time in the early morning and late afternoon because the shadow is too long. I'll have place a size limit on the dial face. Patrick, have I interpreted this correctly? John > >It will be interesting to hear how you get on! > >Regards > >Patrick > >
