Hi Mac, I am finally putting to use your design manual for vertical sundials which show the hours to sunset. Your concept for using such a dial at an airport to show pilots flying VFR the number of hour till sunset was an ideal application. I am proposing a similar dial to the Royal Astronomical Society of Canada for the dark sky site of the Alberta Star Party near Caroline Alberta. All these amateur astronomers will be pacing around their scopes impatiently waiting and wondering when it is going to get dark. They need a dial with Italian hour lines labeled in countdown fashion to determine how long it is till sunset. Constructing such a dial can be my contribution to the club. I keep preaching to them the utility of sundials so this can prove my point.
Thanks for providing the design information. Thanks as well to Fer de Vries for including Italian hour lines in the Zonwvlak program. This made the basic design very easy. Maybe I should also add the sidereal time option suggested by Karl Schwarzinger. Star time on a sundial! Now that would really impress a bunch of astronomers. Roger Bailey Walking Shadow Designs N 51 W 115
