Orrery planetary model

orrery with brass gearwork and paper scale showing eight planets out to Neptune with wooden case by Newton and Company, London, mid 19th century.

Dated to the middle of the nineteenth century this planetary model was made by the London instrument makers Newton and Company. Called an orrery or planetarium, it is a demonstration model to show the motions of the Earth, Moon and planets around the Sun. This example has a wooden base with paper calendar scales and eight planets out to Neptune on long rod-arms. Such devices became popular during seventeenth century especially after Sir Isaac Newton published his universal theory of gravity. To reproduce the motions of the solar system this model employs a hand crank to drive gear wheels. Models of this sort were commonly employed in schools or colleges to teach astronomical principles.