Nikola Tesla - Free-Energy Devices

132 INVENTIONS OF NIKOLA TESLA.the arm, the mere change of configuration of the arm and theconsequent imperceptible displacement being sufficient to disturbthe delicate balance. When it begins to rotate slowly, and tinhandsare held at a proper distance, it is impossible to make eventhe slightest motion without producing a visible effect upon thebrush. A metal plate connected to the other terminal of the coilaffects it at a great distance, slowing down the rotation often toone turn a second.Mr. Tesla hopes that this phenomenon will prove a valuableaid in the investigationof the nature of the forces acting in anelectrostatic or magnetic field. If there is any motion which ismeasurable going on in the space, such a brush would be apt toreveal it. It is, so to speak, a beam of light, frictionless, devoidof inertia. On account of its marvellous sensitiveness to electrostaticor magnetic disturbances it may be the means of sendingsignals through submarine cables with any speed, and even oftransmitting intelligence to a .distance without wires.In operating an induction coil with these rapidly alternatingcurrents, it is astonishing to note, for the first time, the greatimportance of the relation of capacity, self-induction, and frequencyas bearing upon the general result. The combined effectof these elements produces many curious effects. For instance.two metal plates are connected to the terminals and set at a smalldistance, so that an arc is formed between them. This arc />/vventsa strong current from flowing through the coil.If the artbeinterrupted by the interposition of a glass plate, the capacityof the condenser obtained counteracts the self-induction, and astronger current is made to pass. The effects of capacity are themost striking,for in these experiments, since the self-inductionand frequency both are high, the critical capacity is very small,and need be but slightly varied to produce a very considerablechange. The experimenter brings his body in contact with theterminals of the secondary of the coil, or attaches to one or bothterminals insulated bodies of very small bulk, such as exhaustedbulbs, and he produces a considerable rise or fall of potential onthe secondary, and greatly affects the flow of the current throughthe primary coil.In many of the phenomena observed, the presence of the air,or, generally speaking, of a medium of a gaseous nature (usingthis term not to imply specific properties, but in contradistinctionto homogeneity or perfect continuity) plays an important part.