 To ensure the books remained at a consistent angle, Ramelli incorporated an epicyclic gearing arrangement, a complex device that had only previously been used in astronomical clocks.Ramelli's design is unnecessarily elaborate, as he likely understood that gravity would also have been effective (as it is with a Ferris wheel, invented centuries later); but the gearing system allowed Ramelli to display his mathematical prowess.While other people would go on to build bookwheels based on Ramelli's design, Ramelli did not in fact ever construct his own.