A fine and working German tellurium by Paul Räth, Leipzig c. 1895. Telluria are teaching aids used to demonstrate the earth’s movement around the sun, as well as the moon’s movement around the earth. At the centre of the instrument there is a candle representing the sun. The candlelight is focussed by a concave mirror. If one turns a handle, a mechanism makes the earth move round the sun, and a model of the moon simultaneously circulates around the earth that is also turning around its axis.