Let me first get this straight, Leonardo didn't invent the clock. He only made a version of it that was more accurate. The clocks that used an hour and minute hand were usually more accurate. His clock had two separate mechanisms. One mechanism was for hours and one was for minutes. The clock itself is made up of gears, harnesses, and weights. It also has a dial which keeps track of moon phases. He really wanted to have springs instead of weights and harnesses.