Beautiful photographs by Tina Buescher of Jim Donnelly’s orrery based on the mechanism known as “Ferguson’s mechanical paradox.” Good information about the orrery is provided by Ian Coote’s page. As for the “paradox,” well, it boils down to this: the three apparently-identical stacked gears on the end are driven by a single gear, yet move at different rates, which, of course, would be impossible if they were truly identical. News flash: They’re not. But I’m sure it was harder to fight boredom in the 18th century than it is now, and the build is undeniably gorgeous.