About the Model:

An orrery is a very interesting astronomical instrument, used to demonstrate the motion of the planets around the sun and of the satellites around their planets. The first simple planetarium of this kind was constructed between 1704 and 1709 by George Graham, a watchmaker. John Rowley made a made a bigger model of this kind for Charles Boyle, the 4th Earl of Orrery, and called it an orrery in honour of his principal. In its usual form an orrery has a number of concentric tubes arranged around a central axis, on which the sphere representing the sun is mounted. On the upper ends of these tubes, mounted at different levels to avoid interfering, are attached radial rods of various lengths, on the outer ends of which spheres of various sizes are mounted to represent the planets. Similar arrangements apply to the satellites. The lower end of each of the concentric tubes is driven by means of gearing so as to give the correct movements of the heavenly bodies concerned.