----- Original Message ----- From: "John Carmichael" <[EMAIL PROTECTED]> >I think it would be more useful for a sundial designer to have the table in a > more useable form that lists the maximum distance of visibily for different > widths. (I picked 1/16 inch increments because these are the sizes of > hardware like rods, cables and spheres available) > Line width (inches) & maximum distance of visibility(feet) > > 1/16" = 17.9 ft. (from 1/16/.0035) > 1/8" = 35.7 ft. (from 1/8/.0035) > 3/16" = 53.6 ft. etc.
Someone already mentioned that the arc second is no good for us with poor eye sight, and suggested using 3 or perhaps 4 arc seconds. If I've followed the math, then taking a value in the middle (3.438) gives a convenient relationship which allows for unadjusted myopia: - every millimetre of width gives 1 metre of viewing distance - every 1/16 inch gives 5 feet (actually a little over) Steve
