Gears in a watch

In a clock the gear system is connected to the seconds hand, minutes hand and the hour hand. The gear wheel attached to the seconds arm has 120 teeth and is connected to a pendulum having a period of half a second. This means that two teeth are able to advance in 1 second the entire revolution of the seconds hand takes 60 seconds or one minute.This gear is made to  drive another gear train with a ratio of 1:60 and  the minute hand is attached to the last gear in that train. A final train with a ratio of 1:12 is attached to the hour hand.

Here's the link where you can see this in action:

http://electronics.howstuffworks.com/gadgets/clocks-watches/clock3.htm