Pendulum clock made an amazing contribution to the world of time, simply by not paying attention in church. He was standing in the Cathedral of Pisa watching the huge chandelier swinging back and forth from the ceiling of the cathedral. Galileo noticed that no matter how short or long the arc of the chandelier was, it took exactly the same amount of time to complete a full swing. As the pendulum swings left to right, a wheel with teeth turns the hour and minute hands. The second hand on the clock was developed at this time. This clock was more accurate than any previous clock invented.