Motion Works: the 12:1 Reduction

Under the dial, a little gear set makes the hour hand crawl at one-twelfth the minute hand

$\omega_{\text{hour}}=\tfrac{1}{12}\,\omega_{\text{minute}}$

12:00:00

Speed 720× 720× ≈ 1 hour per 5 s

Set the time by turning the hands: a friction-fit cannon pinion lets the hands slip without driving the train backward.