Cathedral and Orrery

I had some time this weekend to look round Derby and see what's changed, or not, in the twenty or so years since I last spent some proper time in the city - usually I just get a view of the bus station on my way through to visit Mum.
So I wandered up towards the cathedral today and came across this monument to Joseph Wright (1734-1797) in Irongate. Wright was born here and trained in London with Thomas Hudson, whose pupils included Joshua Reynolds. One of Wright's best-known paintings is 'A Philosopher lecturing on the Orrery', and this is represented in abstract form capping this memorial to him (so the plaque on it informs me).
An orrery is a mechanical model of the solar system that illustrates or predicts the relative positions and motions of the planets and moons. Its representation here is also interestingly reminiscent of the models of atomic structure that I remember from my schooldays.