Truly Chinese, such clocks are in the form of an oriental drum, designed to be supported vertically on a stand. The cases are pierced engraved chased brass cylinders of varying diameters, all about 3in. Deep. The movements vary, but all are copies of European timepieces and similar in workmanship. Since the Chinese hour system closely matched the western diurnal system there was no need to adapt the mechanism in any major way. Chinese clocks have twelve fixed equal hours, with no way of altering either the dial or the rate of escapement for a system of varying hour lengths. Most have alarms, consisting of a brass setting disc, with six small knobs and a window, placed over another disc with the Twelve Terrestrial Branches, representing the twelve fixed hours, each marked with a Chinese character, closely associated with the twelve animals of Chinese folklore, engraved on it, fastened directly to the dial plate. Not many of these clocks were made and, although they can be found, they are not common.