The pedometer is used to measure distances traveled. It consists of a wheel and a handle. One end of the handle is attached to the center of the wheel; the other end carries a brass recording disk. Thanks to a gear mechanism, every turn of the wheel (whose circumference is, of course, known) is registered on the disk. The instrument, probably from the workshop of Christoph and Hans Christoph Schissler, belongs to the group of instruments that Prince Mattias de' Medici bought in Germany in 1635. The Cimento academicians used it to attempt to measure the arc of the terrestrial meridian.