Cambridge Sundials

Sundials have always fascinated me, the gnomon, which casts a shadow, is straight forward it just has to be parallel to the earth's axis. The scale, however, is more complicated as the lines have to represent the points at which the shadow is cast at the appropriate time for every season of the year and requires quite a bit of mathematical calculation. This picture is of three of the sundials on this tower all of which are of unique design.