1 Opinion of the Court. apparatus so as to place it in resonance with any particular transmitting station, his patent equally plainly suggested the use of the Lodge variable inductance as a means of adjusting the tuning of the receiving antenna. Stone's 1902 amendments also suggested that an "elevated conductor that is aperiodic may be employed"i. e., one having very weak natural periodicity and consequently "adapted to receive or transmit all frequencies." But this suggestion was accompanied by the alternative recommendation in the 1902 amendments that the antenna circuits at transmitter and receiver "may with advantage be made resonant to a particular frequency,” i. e., be periodic. No inference can be drawn from this that only an aperiodic antenna was contemplated either by the application or the amendments. The application was sufficiently broad to cover both types, since both were suitable means of achieving under different conditions the results which the application described and sought to attain. The amendments thus merely clarified and explained in fuller detail two alternative means which could be employed in the invention described in the original application, one of those means being the construction of the antenna so as to be highly resonant, i. e., tuned, to a particular frequency." The only respects in which it is seriously contended that Marconi disclosed invention over Stone are that Marconi explicitly claimed four-circuit tuning before 17 This is borne out by the subsequent letter from Stone to the Commissioner of Patents dated June 7, 1902. Stone there refers to a letter by the Patent Office saying that the statement that a simple harmonic wave developed in the closed circuit "can be transferred to the elevated conductor and from the latter to the ether without change of form" is "an argument the soundness of which the Office has no means of testing." Stone replied with arguments to show that the vibrations radiated by the antenna circuit would be sufficiently pure for practical purposes either if the antenna circuit were Opinion of the Court. 320 U.S. Stone had made it explicit by his 1902 amendment, and that Marconi disclosed means of adjusting the tuning of each of his four circuits whereas Stone had explicitly shown adjustable tuning only in the two closed circuits. But we think that neither Marconi's tuning of the two antenna circuits nor his use of the Lodge variable inductance to that end involved any invention over Stone. Two questions are involved, first, whether there was any invention over Stone in tuning the antenna circuits, and, second, whether there was any invention in the use of the Lodge variable inductance or any other known means of adjustment in order to make the tuning of the antenna circuits adjustable. For reasons already indicated we think it clear that Stone showed tuning of the antenna circuits before Marconi, and if this involved invention Stone was the first inventor. Stone's application emphasized the desirability of tuning, and disclosed means of adjusting the tuning of the closed circuits. His very explicit recognition of the increased selectivity attained by inductive coupling of several resonant circuits plainly suggested to those skilled in the art that the antenna circuit could with advantage be a resonant circuit, that is to say a tuned circuit, and hence that it was one of the circuits to be tuned. He stressed the importance of tuning "by any suitable device" the "apparatus" at transmitter and receiver, which included at both an antenna circuit. aperiodic, or if it had a fundamental which was of the same frequency as that of the forced vibrations impressed upon it, although they would not be pure if the antenna circuit had a marked natural periodicity and was untuned. This letter, while somewhat later in date than the amendments, reinforces the conclusion that the purpose of those amendments was to explain more fully the details of theory and practice necessary to the success of the idea underlying Stone's original invention. 1 Opinion of the Court. Tuning of the antenna circuit was nothing new; Lodge had not only taught that the antenna circuits at transmitter and receiver should be tuned to each other but had shown a means of adjusting the tuning which was the precise means adopted by Marconi, and which Stone had, prior to Marconi, used to tune his closed circuit-the variable inductance. Tesla, too, had shown the tuning of the antenna circuit at the transmitter to the frequency developed by the charging circuit, and the tuning of both circuits at the receiver to the frequency thus transmitted. Thus Marconi's improvement in tuning the antenna circuits is one the principles of which were well understood and stated by Stone himself before Marconi, and the mechanism for achieving which had previously been disclosed by Lodge and Stone.18 Since no invention over Stone was involved in tuning the antenna circuits, neither Marconi nor Stone made an invention by providing adjustable tuning of any of the circuits or by employing Lodge's variable inductance as a means of adjusting the tuning of the resonant fourcircuit arrangement earlier disclosed by Stone's application and patented by him. No invention was involved in employing the Lodge variable inductance for tuning 18 It is not without significance that Marconi's application was at one time rejected by the Patent Office because anticipated by Stone, and was ultimately allowed, on renewal of his application, on the sole ground that Marconi showed the use of a variable inductance as a means of tuning the antenna circuits, whereas Stone, in the opinion of the Examiner, tuned his antenna circuits by adjusting the length of the aerial conductor. All of Marconi's claims which included that element were allowed, and the Examiner stated that the remaining claims would be allowed if amended to include a variable inductance. Apparently through oversight, Claims 10 and 11, which failed to include that element, were included in the patent as granted. In allowing these claims the Examiner made no reference to Lodge's prior disclosure of a variable inductance in the antenna circuit. Opinion of the Court. 320 U.S. either the closed or the open circuits in lieu of other structural modes of adjustment for that purpose. The variable inductance imparted no new function to the circuit; and merely making a known element of a known combination adjustable by a means of adjustment known to the art, when no new or unexpected result is obtained, is not invention. Peters v. Hanson, 129 U. S. 541, 550-51, 553; Electric Cable Co. v. Edison Co., 292 U. S. 69, 79, 80, and cases cited; Smyth Mfg. Co. v. Sheridan, 149 F. 208, 211; cf. Bassick Mfg. Co. v. Hollingshead Co., 298 U. S. 415, 424-5 and cases cited. Stone's conception of his invention as disclosed by his patent antedated his application. It is carried back to June 30, 1899, seven months before his application, when, in a letter to Baker, he described in text and drawings his four-circuit system for wireless telegraphy in substantially the same form as that disclosed by the application. His letter is explicit in recommending the tuning of the antenna circuits. In part he wrote as follows: "Instead of utilizing the vertical wire [antenna] itself at the transmitting station as the oscillator, I propose to impress upon this vertical wire, oscillations from an oscillator, which oscillations shall be of a frequency corresponding to the fundamental of the wire. Similarly at the receiving station, I shall draw from the vertical wire, only that component of the complex wave which is of lowest frequency. "If now the fundamental of the wire at the receiving station be the same as that of the wire at the transmitting station, then the receiving station may receive signals from the transmitting station, but if it be different from that of the transmitting station, it may not receive those signals. "The tuning of these circuits one to another and all to the same frequency will probably be best accomplished 1 Opinion of the Court. empirically, though the best general proportions may be determined mathematically." On July 18, 1899, Stone again wrote to Baker, mathematically demonstrating how to achieve the single frequency by means of forced vibrations. He expressed as a trigonometric function the form taken by the forced wave "if the period of the impressed force be the same as that of the fundamental of the vertical wire." He also pointed out that the transmitting circuit which he had disclosed in his earlier letter to Baker, "is practically the same as that employed by Tesla," except that Stone added an inductance coil in the closed circuit "to give additional means of tuning" and to "swamp" the reactions from the coil of the oscillation transformer and thus loosen the coupling between the open and closed circuit of the transmitter.1 His recognition of the effect upon the current in the antenna if it is of the same period as the charging circuit; his statement that his transmitting system was the same as that employed by Tesla; his recognition that the fundamental of the receiver should be the same as that of the transmitter antenna when used for the transmission of a single frequency, and finally his statement that all four circuits are to be tuned, "one to another and all to the same frequency," all indicate his understanding of the principles of resonance and of the significance of tuning the antenna circuits. Stone disclosed his invention to others, and in January, 1900, described it to his class at the Massachusetts Institute of Technology. Before 1900 he was diligent in obtaining capital to promote his invention. Early in 1901 a syndicate was organized to finance laboratory experiments. The Stone Telegraph & Telephone Co. was organized in December, 1901. It constructed several experimental stations in 1902 and 1903; beginning in 1904 19 See footnote 13, supra. |