A
tellurion (also spelled
tellurian,
tellurium, and yet another name is
loxocosm), is a
clock, typically of French or Swiss origin, surmounted by a mechanism that depicts how day, night and the seasons are caused by the movement of the Earth on its
axis and its orbit around the sun. The clock normally also displays the age of the moon, and the four-year (
perpetual) calendar.