Drum model orrery, 1813-1822.
© Science Museum / Science & Society Picture Library
This planetary model was designed by the astronomer William Pearson (1767-1847) and made in London by John Fidler. Called an orrery or planetarium, it is a demonstration model to show the motions of the Earth, Moon and planets around the Sun. It has a bras drum base with a pedestal stand and seven planets (Mercury-Uranus) on long rod-arms. Such devices became popular during the 17th century, especially after Sir Isaac Newton (1642-1727) published his universal theory of gravity in 1687. To reproduce the motions of the solar system this model employs a hand crank to drive the gear wheels. This elaborate orrery is the only surviving example of several planetary models devised by William Pearson.