| imple pendulum is said to date back to China, | | | | keeping the mean length of the pendulum the |
| sometime in two hundred A.D. In its most basic | | | | same. |
| form a pendulum is defined as a weight | | | | Some vintage pendulum clocks utilized what was |
| suspended from a fixed point so that it will swing | | | | known as a mercurial pendulum. The mercurial |
| freely back and forth. The motion is created by | | | | pendulum had a single rod, but the weight at the |
| the force of gravity and the impulse the | | | | end contained mercury. As the rod lengthened, |
| pendulum receives from its own motion. A simple | | | | the mercury would expand upward. As the rod |
| pendulum may consist of a heavy body, | | | | shortened, the mercury would expand downward |
| suspended from a fixed pint by a string and | | | | thus preserving the length of the pendulum. |
| caused to swing or vibrate without much friction. | | | | In a pendulum and weight clock movement, the |
| The discovery of the pendulum is probably the | | | | basic components have not changed much over |
| single most important development in human | | | | the years. The required parts include a weight or |
| timekeeping. Dating back to fifteen eighty two, | | | | spring, which supplies the power for the |
| the controversial Italian scientist Galileo Galilei was | | | | movement. The escapement acts to connect a |
| the first to understand that a swinging pendulum | | | | balance wheel or pendulum to the movement. |
| could accurately power a clock movement. As a | | | | Through a train of gears and rods, movement is |
| brilliant physicist, Galileo calculated that a swinging | | | | transmitted to the hands. In a weight system, the |
| pendulum, used in combination with a traditional | | | | weight is attached to a cord or chain that is |
| mainspring would increase the accuracy of | | | | wound around a drum. As the weight descends, |
| timekeeping. His design was not fully developed | | | | the unwinding of the cord imparts movement to |
| until almost seventy years later when a | | | | the gears. The motion is regulated by the motion |
| Dutchman fully integrated the pendulum into a | | | | or vibration of the pendulum. |
| working pendulum clock. | | | | As motion is transmitted to the movement, a |
| Simple clock pendulums are usually noting more | | | | pinion gear attached to the escapement connects |
| than a hanging circular piece of metal called the | | | | with cogs called leaves. The leaves are on a larger |
| bob or disk. The bob is attached to the clock | | | | wheel whose pinion connects with another large |
| movement by a piece of cable or metal rod. The | | | | wheel and so on until the necessary number of |
| time of the vibration or cycle for the same | | | | wheels is used to produce a rotation. The rotation, |
| pendulum will vary in different locations. For | | | | once every twelve hours, is carried to the hour |
| example, the vibration of a pendulum located at | | | | hand. Another wheel attached to the minutes |
| the earths equator will decrease as is it moved | | | | hand, makes a complete rotation every hour. The |
| towards one of the Earths poles. | | | | movement of the wheelworks is controlled by |
| Since the rod in most clock pendulums lengthens | | | | the vibrations or swinging of the pendulum. |
| in the summer and shortens in the winter, a | | | | The clock can be made to run faster or slower |
| means of preserving the uniform length of the | | | | by shortening or lengthening the pendulum. At the |
| pendulum is needed. In what had become known | | | | bottom of the bob or pendulum is a threaded |
| as regulator clocks, the pendulum rod consists of | | | | adjusting rod. The fine threads on the adjusting |
| a frame of rods made from different metals. The | | | | rod aid in making very precise adjustments to the |
| rods are arranged so that some of the rods | | | | speed at which the pendulum swings. |
| expand downward and others expand upward, | | | | |