Orrery, tellurium or planetary model, c. 1712, made for Charles Boyle, the fourth Earl of Orrery by John Rowley, Fleet Street, London.
Dated 1712-3, this planetary model was made by the London instrument maker, John Rowley. It is a demonstration device to show the motions of the Earth and Moon around the Sun. Such apparatus became popular from around 1700, especially after Sir Isaac Newton published his universal theory of gravity. This particular example was made for Charles Boyle, the fourth Earl of Orrery in Ireland. Rowley may have been inspired by an earlier example made by the London clock maker, George Graham. Much admired in its day, it was given the title 'orrery' after its owner – possibly a play on the word ‘horary’, meaning hours. This name was subsequently applied to later planetary models or machines, although the alternative term 'tellurium' is often used to describe devices such as this that show only the Earth, Moon and Sun.