Man's quest for free power
The first law of thermodynamics says, in effect, that you cannot get something for nothing—but that has never stopped people from trying. It is scientifically impossible to build a machine that will run without an external energy supply, yet for centuries inventors have persisted with designs for perpetual-motion machines.
One of the most common was a gravity-operated overbalancing wheel. If a weight is attached near the top of an upright wheel, the wheel will rotate until the weight reaches the bottom. If it were possible to arrange a series of weights around the wheel so that those on the way down were farther from the wheel's center
than those on the way up, the result would be an overbalancing wheel that would keep on turning.
Leonardo's attempt
Such a device was designed in the 13th century by the French architect Villard de Honnecourt.
His wheel had seven pivoted hammers that stuck out on the falling side and folded in on the rising
Even Leonardo da Vinci designed one in the 15th century, using four radial arms. At the end of each was a metal sphere containing a little mercury. The shifting weight of the mercurv was supposed to keep the wheel turning.
A balanced wheel will keep turning for sometime, simply because it slows down very gradually. This explains the apparent success of an overbalancing wheel, 14 feet across, built in the 17th century by Edward Somerset, Marquis of Worcester. It was started by hand, then rot on its own for the few minutes that observers were permitted to watch. But once they had left, friction began to slow it down until it eventually came to a complete halt.
Other "perpetual motion" machines used liquids. One naive effort, proposed by the Abbé de la Roque in 1686, consisted of a funnel with its long stem curved around and upward in such 2 way as to discharge any liquid in it back into the funnel. The inventor hoped that the weight of the water in the funnel would force liquid up around the stem and back into the funnel and function indefinitely.
The fact is that the only way to force water up such a funnel is to install a pump—which would defeat the idea of perpetual motion. For the truth is that you cannot get something for nothing—particularly from machinery.
