Nikola Tesla Patents
Again, another contrivance capable of being utilized in detecting feeble electrical effects, consists of two conducting plates or terminals which have preferably wires of some length attached to them and are bridged by a mass of minute particles of metal or other conducting material. Normally these particles, lying loose, do not connect the metal plates, but under the influence of an electrical disturbance produced at a distance, evidently owing to electrostatic attraction, they are pressed firmly against each other, thus establishing a good electrical connection between the two terminals This change of state may be made use of in a number of ways for the above purpose. Still another modified device which may be said to embody the features of both the former, is obtained by connecting the two conducting plates or terminals permanently with the poles of a battery which should be of very constant electro-motive force. In this arrangement a distant electrical disturbance produces a twofold effect on the conducting particles and insulating films between them. The former are brought nearer to each other in consequence of the sudden increase of electrostatic attraction, and the latter, owing to this as well as by being reduced in thickness or in number, are subjected to a much greater strain which they are unable to withstand. It will be obviously noted from the preceding that, whichever of these or sÃmilar contrivances be used, the sensitiveness and, what is often still more important, the reliability of operation is very materially increased by a close adjustment of the periods of vibration of the transmitting and receiving circuits, and, although such adjust(7) 231
