Perpetual Motion (of machines) is defined as “The motion of a machine that, once activated, would run forever unless subject to an external force”; is it possible? Let’s start off where it all began. Ever since the 8th century man has been attempting to build Perpetual Motion Machines, many were designs of a system of weights on a wooden wheel. These work in a simple cycle starting with the weights on the left side, these weights hang close to the wheel resulting in a lower torque; but when the weights reach the top, a toppling motion occurs creating more torque which pulls the wheel down.
Later during the 19th century, with the use of electricity, entrepreneurs planned and built machines in which a motor provided motion, which in turn, supplied power back to the motor. The goal was perpetual motion and a “free” source of energy. Plan’s even included self sustaining automobiles.
The Dipping Bird is a novelty device and is believed by many to be a perpetual motion device.
The system consists of a container of water and a glass bird filled with an easily vaporized liquid. When the bird’s ‘beak’ dips into the water, it draws the liquid up causing it to be top heavy. This results in a lifting action, when the liquid rises, right about the time he becomes horizontal, the tube in the lower bulb is no longer obstructed by the liquid in the lower bulb and the two pressure chambers equalize and fall.
This causes the bird fall but only moments later to have the liquid be drawn back up due to the effects of Entropy. These systems work, but are they Perpetual Motion Machines? No. The wheel device will go on for a long period of time; but during the cycles a force is acting upon which you can’t see. This force is called friction, and it will eventually stop the machine. As for the bird, friction is acting upon it as well; but before it has an effect on it, the water level (the energy) necessary for the device will have evaporated below a usable level.