Nikola Tesla Patents
420 which may be a frictional or an inductive one, is not absolutely necessary, but it is of advantage to use it in order to facilitate adjustment, and for this puspose it may be made variable in any convenient and preferably continuous manner. Assuming that the disturbances which are to be investigated or utilized for some practical end, are rays identical with, or resembling those of ordinary light, the sensitive device a may be a selenium cell, properly prepared so as to be high susceptible to the influence of the rays, the action of which should be intensified by the use of a reflector A shown in the drawing. It is well known that, when cells of this kind are exposed to such rays of greatly varying intensity, they undergo corresponding modifications of their electrical resistance, but in the ways they have been heretofore used, they have been of very limited utility. In addition to the circuit including the sensitive device or cell a another circuit is provided, which is likewise connected to the terminals T T' of the condenser. This circuit, which may be called the receiving circuit, includes the receiver R and, in series with it, a device d before referred to, which performs the duty of periodically discharging the condenser through the receiver. It will be noted that, as shown in Fig. 1, the receiving circuit is in permanent connection with the battery and condenser terminal T, and it should be stated that it is sometimes desirable to entirely insulate the receiving circuit at all times except the moments when the device d operates to discharge the condenser, thus. preventing any disturbing influence which might otherwise be caused in this circuit by the battery or the condenser during the period when the receiver should not be acted upon. In 10 This page retyped from microfilm for better readability - Ed.] 1
