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J. Perelman
"Entertaining physics". Book 1.
Chapter 5. Properties of liquids and gases


In this book we have considered for several imaginary “perpetual motion” and found the hopelessness of attempts to invent. Now will talk about the type of the engine, i.e. about this engine, which is able to operate indefinitely without worries with our side, because draws the energy it needs from its inexhaustible reserves in the environment. All of course, saw the barometer - mercury or metal. In the first barometer the top of the mercury column constantly to rise and fall depending on changes in atmospheric pressure; in metal - from the same causes constantly fluctuating arrow. In the eighteenth century one inventor used the movement of the barometer for watch winding mechanism and thus has built watches which themselves were wound up and went non-stop, without requiring any plant. The famous English engineer and astronomer Ferguson saw this interesting invention and spoke of him (in 1774):

“I have examined the above watches, which are in continuous movement by the lifting and lowering of mercury arranged in a kind of barometer; there is no reason to think that they ever stopped, as nameplease them motive force would be sufficient to maintain the hours in the course of a year even after the complete elimination of the barometer. I must say in all honesty that it shows detailed acquaintance with these watches, they are the most ingenious mechanism which I have ever seen, and the idea and the execution.

Unfortunately, the clock these have not survived to our time - they were stolen, and their location is unknown. There remained, however, the drawings of their designs have been mentioned astronomer, so there is the possibility to restore them.

The device gratuitous engine of the XVIII century

Part of the mechanism of this watch includes a mercury barometer large sizes. In a glass box suspended in the frame and tilted over her neck down a large flask is about 150 kg of mercury. Both vessels fortified movable one relative to another; and by an ingenious system of levers is achieved that with increasing atmospheric pressure, the flask is lowered and the urn rises, decreasing as pressure - on the contrary. Both movements are forced to rotate the small gear is always in one direction. The wheel is stationary only when full invariance atmospheric pressure, but during pauses the clock mechanism moves before the accumulated energy of the falling weights. It is not easy to arrange so that the weights simultaneously rose up and moved her fall mechanism. However, vintage watchmakers were resourceful enough to cope with this task. Turned out to be even that the energy fluctuations of the atmospheric pressure was much greater than the demand, i.e., the weights went up faster than down; it took so special device for periodic shutdown of falling weights, when they had reached the highest point.

It is easy to see important fundamental difference between this and similar type of engines from “eternal” engines. In gratuitous engines energy is not created out of nothing, as wanted to arrange the inventors of perpetual motion; it is drawn from the outside, in our case from the surrounding atmosphere, where it is accumulated by the solar rays. Almost gratuitous engines would be as beneficial as these “eternal” engines, if their design was not too expensive compared to deliver their energy (as in most cases it happens).

A little later we will look at other types gratuitous engine and we will show by example why the industrial use of such mechanisms is generally not favorable.

Entertaining physics J. Perelman


System Orphus


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