"A Philosopher Lecturing on the Orrery" shows an early mechanism for demonstrating the movement of the planets around the sun. The Scottish scientist, astronomer and lecturer James Ferguson undertook a series of lectures in Derby in July 1762. They were based on his book "Lectures on Select Subjects in Mechanics, Hydrostatics, Pneumatics, Optics &c.", published in 1760. In order to illustrate his lectures he used various machines, models and instruments. Wright possibly attended Ferguson's lecture, especially as tickets for the event were available from John Whitehurst, his close neighbour, the clockmaker and scientist. The artist could also have drawn on Whitehurst's practical knowledge to find out more about the orrery and its operation.