> It looks like a glass sphere held in the center of a small equatorial
> sundial. The image of the sun focuses to a point at some short
> distance away from the surface of the glass sphere. Held in place
> at this distance away from the glass and following the curve of
> the sphere is a piece of waxpaper against a dark background.
> When the sun shines, the waxpaper is scorched. When the sun
> is behind the clouds, it is not scorched. The result is a recording of the
> amount of sunshine seen at that location on that day.
There's one listed at: http://www.inta.net.au/js/Meteorology.html
