Patent model of orrery planetary mechanism, 1865

Patent model of improved orrery by John G. Moore of Philadelphia, US Patent 51072 dated 21st November 1865, with original tag.

This is a model of Moore's patent orrery, an American patent model made by John G. Moore of Philadelphia. Apart from those taken into the Smithsonian, very few patent models survived the various sales, fires and bankruptcies which plagued the once considerable collection of these models.

The design of this orrery incorporated some slight modifications to previous orrery design. This gave improved accuracy, most notably, the Earth's axis moves round a small circle to give an elliptical orbit around the Sun. The angle of the Earth's orbit round the Sun can be varied. The Moon is fixed to a cam follower arm so that it moves in an inclined orbit round the Earth. Variations on this type of orrery became popular in the following half century, for example the Laing orrery of ca. 1915 seen later in the models sequence.