Nikola Tesla U.S. Patent 725,605 - System of Signaling Patent Wrapper Page 47

J Bieli 92 9. In a receiving apparatus, the combination of a plurality of sensitive circuits, each tuned to respond to different waves or impulses of a given)kind or class, a receiving circuit controlled by the sensitive circuits and a device connected with the receiving circuit adapted to be operated when said circuit is completed by the conjoint action of two or more of the sensitive circuits, as set forth." In submitting the application as thus amended for reconsideration, we desire to state that it is not our purpose in the amendment to limit the claims to a narrower scope than was contemplated originally, but merely to define with greater accuracy the distinctively novel feature of applicant's invention. The fundamental idea of Mr. Tesla's improvement is the use of a receiver comprising two or more circuits which are tuned to respond to impulses of different character, and to the conjoint action of which the operation of the receiver is due. The prior art, fairly though not fully illustrated by the patents cited by the Examiner, contains no instance of this principle of which we are aware. In systers of telegraphy currents, impulses or oscillations of different kinds have been transmitted to a receiver and by their conjoint effect, an operation of the receiver produced, but in every instance where the receiver had more. than one circuit, each circuit was either capable of responding to all of the currents or impulses or some mechanical device was employed for confining the action of one current or set of impulses to one circuit. The patent to cardwell is representative of this latter class. The British patent Welson -13661