"The clock offered to Charlemagne had ... a dial containing twelve doors. At the appropriate hour, the appropriate door would open and out would drop the appropriate number of small golden balls, which fell one at a time onto a brass drum fitted with a taut square of goat's hide. When the midnight hour had arrived and its twelve balls struck their twelve beats, twelve miniature horsemen rode forth and closed the twelve doors."
—from The Reasonable Horologist, by the Rev. Kenner Davenport, 1783 (via Tinkers, by Paul Harding, 2009)