19th century illustration of the bookwheel (sometimes called a reading wheel) is a type of rotating bookcase designed to allow one person to read a variety of heavy books in one location with ease. The books are rotated vertically similar to the motion of a water wheel, as opposed to rotating on a flat table surface. The design for the bookwheel originally appeared in a 16th-century illustration by Agostino Ramelli, at a time when large books posed practical problems for readers. Ramelli's design influenced other engineers and, though now obsolete, inspires modern artists and historians. To ensure that the books remained at a constant angle, Ramelli incorporated an epicyclic gearing arrangement, a complex device that had only previously been used in astronomical clocks