A skeleton clock is any clock or wristwatch, though typically mechanical in nature, in which the parts that usually conceal the inner workings of the mechanism have been removed or significantly modif
English Skeleton Clock by Smith & Sons. Dated 1864
French Great Wheel Skeleton Clock. Circa 1840
A gear or gearwheel, also called a toothed wheel, is a rotating machine part typically used to transmit rotational motion or torque by means of a series of "teeth" that engage with compatible teeth of
Bronze gear with pawl from Luoyang, China, dated to the Warring States period (475–221 BC)
Modern model of a south-pointing chariot
Wooden cogwheel driving a lantern pinion or cage gear
A cast gearwheel (above) meshing with a cogged mortise wheel (below). The wooden cogs are held in place by nails.