Re: Sundials at Train Stations

[Richard Koolish]

The eye/brain is very good at seeing lines, and can see lines thinner
than the usual 1 arcminute given as the resolution of the eye.
20/20 vision is based on reading letters that are 5 arcminutes high
that have 1 arcminute features (line width and gaps).  So this might
give you an idea of how big to make lines and numbers on a sundial,
although I would guess that you shouldn't require 20/20 vision among
the viewers.