Orreries: Mechanical Models of the Solar System
Image: Orrery, Tellurium & Lunarium detail
Source: Museum Victoria
An orrery is a mechanical model of the solar system. The first orrery was made around 1713 and is generally attributed to watchmaker George Graham. A copy of Graham's machine was made for Charles Boyle, the Fourth Earl of Orrery, who gave his name to the model.
The 18th and 19th centuries were a time of renewed interest in automata, reflecting the idea that mechanical science could unlock the secrets of nature. Mechanisms of this period included flute players, singing birds, and even a lawyer arguing in court.
Orreries were popular educational devices, yet they are inaccurate representations of the solar system. Most orreries correctly represent the relative speeds of different planets, however few accurately show the relative sizes of the planets and their planetary orbits, or the elliptical shape of the orbits.
This orrery, manufactured by Benjamin Martin in 1770, contains a mechanism that can produce elliptical orbits. It also differs from earlier orreries by having the planets on extended arms, rather than fixed on rotating plates. Martin was one of the most important instrument makers of his time and was particularly known for his microscopes.