>P.S. Does anyone know how the Wheatstone sundial works? All I know is:
In Cousin's sundial book, Wheatstone is credited with inventing a dial that tells time by means of the polarization of sunlight, which varies in a given direction as the sun's angle changes. It shows a photograph of his device, which resembles (to me) a rotatable microscope and which contains a polarizer and prism. I also would be interested in any sources of further detail. Ron Doerfler
