Before the invention of the mechanical clock during the end of 13th century, water clocks and sand clocks were used to keep the time. The newly invented mechanical clocks neither had a pendulum nor the hands. See one of the examples in the photo on the left. A suspended weight would rotate the mechanical wheels and the clock would strike at every hour. With the passage of time, various new models were manufactured. Though each of it had a pendulum, there was no standard format regarding the movement of its hands.