Opinion of the Court. 320 U.S. or 1905 it built wireless stations and sold apparatus, equipped a Navy collier and some battleships, and it applied for a large number of patents. The apparatus used in the stations is described by Stone's testimony in this suit as having resonant open and closed circuits loosely coupled inductively to each other, at both the transmitter and receiver, and all tuned to the same wave length, as described in his letters to Baker and his patent. We think that Stone's original application sufficiently disclosed the desirability that the antenna circuits in transmitter and receiver be resonant to the same frequency as the closed circuits, as he expressly recommended in his patent. But in any event it is plain that no departure from or improper addition to the specifications was involved in the 1902 amendments, which merely made explicit what was already implicit. Hobbs v. Beach, 180 U.S. 383, 395-7. We would ordinarily be slow to recognize amendments made after the filing of Marconi's application and disclosing features shown in that application. Cf. Schriber-Schroth Co. v. Cleveland Trust Co., 305 U. S. 47, 57; Powers-Kennedy Corporation v. Concrete Co., 282 U. S. 175, 185-6; Mackay Radio Co. v. Radio Corporation, 306 U. S. 86. But here Stone's letters to Baker, whose authenticity has not been questioned in this case, afford convincing proof that Stone had conceived of the idea of tuning all four circuits prior to the date of Marconi's invention. Cf. Bickell v. Smith-Hambury-Scott Welding Co., 53 F.2d 356, 358. It is well established that as between two inventors priority of invention will be awarded to the one who by satisfying proof can show that he first conceived of the invention. Philadelphia & Trenton R. Co. v. Stimpson, 14 Pet. 448, 462; Loom Co. v. Higgins, 105 U. S. 580, 593; Radio Corporation v. Radio Laboratories, 293 U. S. 1, 11-13; Christie v. Seybold, 55 F. 69, 76; Automatic Weighing Mach. Co. v. Pneumatic Scale Corp., 158 F. 415, 417 1 Opinion of the Court. 22; Harper v. Zimmermann, 41 F. 2d 261, 265; Sachs v. Hartford Electric Supply Co., 47 F. 2d 743, 748. Commercial success achieved by the later inventor and patentee cannot save his patent from the defense of anticipation by a prior inventor.20 Compare Smith v. Hall, 301 U. S. 216 with Smith v. Snow, 294 U. S. 1. To obtain the benefit of his prior conception, the inventor must not abandon his invention, Gayler v. Wilder, 10 How. 477, 481, but must proceed with diligence to reduce it to practice. We think Stone has shown the necessary diligence. Compare Radio Corporation v. Radio Laboratories, supra, 13, 14. The delay until 1902 in including in his patent specifications the sentences already referred to, which explicitly provide for tuning of the antenna circuits, does not in the circumstances of this case show any abandonment of that 20 Even if the lack of invention in Marconi's improvement over Stone-making adjustable the tuning of the antenna circuits which Stone had said should be tuned-could be said to be in sufficient doubt so that commercial success could aid in resolving the doubt, Thropp's Sons Co. v. Seiberling, 264 U. S. 320, 330; DeForest Radio Co. v. General Electric Co., 283 U. S. 664, 685; Altoona Theatres v. TriErgon Corp., 294 U. S. 477, 488, it has not been established that the alleged improvement contributed in any material degree to that success. Compare Altoona Theatres v. Tri-Ergon Corp., supra. Marconi's specifications disclose a large number of details of construction, none of which is claimed as invention in this patent, in which his apparatus differed from, and may have been greatly superior to, Stone's. Many of these formed the subject of prior patents. After his application for his patent, as well as before, Marconi made or adopted a great number of improvements in his system of wireless telegraphy. Two of his engineers have written that a major factor in his successful transmission across the Atlantic in December, 1901, was the use of much greater power and higher antennae than had previously been attempted, an improvement in no way suggested by the patent here in suit. Fleming, Electric Wave Telegraphy, 449-53; Vyvyan, Wireless Over Thirty Years, 22-33. Indeed both are agreed that in the actual transmission across the Atlantic tuning played no part; the receiver antenna consisted of a wire suspended by a kite which rose Opinion of the Court. 320 U.S. feature of Stone's invention since, as we have seen, the idea of such tuning was at least implicit in his original application, and the 1902 amendments merely clarified that application's effect and purport. Marconi's patent No. 763,772 was sustained by a United States District Court in Marconi Wireless Telegraph Co. v. National Signalling Co., 213 F. 815, and his invention as specified in his corresponding British patent No. 7777 of 1900, was upheld in Marconi v. British Radio & Telegraph Co., 27 T. L. R. 274, 28 R. P. C. 18. The French court likewise sustained his French patent, Civil Tribunal of the Seine, Dec. 24, 1912. None of these courts considered the Stone patent or his letters. All rest their findings of invention on Marconi's disclosure of a four-circuit system and on his tuning of the four circuits, in the and fell with the wind, varying the capacity so much as to make tuning impossible. Ibid. By 1913, when he testified in the National Electric Signalling Co. case, that "due to the utilization of the invention" of this patent he had successfully transmitted messages 6,600 miles, he had, after almost continuous experimentation, further increased the power used, developed new apparatus capable of use with heavy power, enlarged his antennae and adopted the use of horizontal, "directional" antennae, and made use of improved types of spark gaps and detecting apparatus, including the Fleming cathode-anode tube, the crystal detector, and sound recording of the signals-to mention but a few of the improvements made. He had also discovered that much greater distances could be attained at night. See Vyvyan, supra, 34-47, 55-60. The success attained by the apparatus developed by Marconi and his fellow engineers by continuous experimentation over a period of years-however relevant it might be in resolving doubts whether the basic four-circuit, tuned system disclosed by Marconi, and before him by Stone, involved invention-cannot, without further proof, be attributed in significant degree to any particular one of the many improvements made by Marconi over Stone during a period of years. The fact that Marconi's apparatus as a whole was successful does not entitle him to receive a patent for every feature of its structure. 1 Opinion of the Court. sense of rendering them resonant to the same frequency, in both of which respects Stone anticipated Marconi, as we have seen. None of these opinions suggests that if the courts had known of Stone's anticipation, they would have held that Marconi showed invention over Stone by making the tuning of his antenna circuit adjustable, or by using Lodge's variable inductance for that purpose. In Marconi Wireless Telegraph Co. v. Kilbourne & Clark Mfg. Co., 239 F. 328, affirmed 265 F. 644, the district court held that the accused device did not infringe. While it entered formal findings of validity which the Circuit Court of Appeals approved, neither court's opinion discussed the question of validity and that question was not argued in the Circuit Court of Appeals."1 Marconi's reputation as the man who first achieved successful radio transmission rests on his original patent, which became reissue No. 11,913, and which is not here 21 A preliminary injunction restraining infringement was entered in Marconi Wireless Tel. Co. v. DeForest Co., 225 F. 65, affirmed, 225 F. 373, both courts, without independent discussion of the validity of the patent, determining that the decision in the National Signalling Co. case justified the grant of preliminary relief. A preliminary injunction was also granted in Marconi Wireless Tel. Co. v. Atlantic Communications Co., an action brought in the Eastern District of New York. Stone's letters were introduced in evidence in the Atlantic Communications Company case and the Kilbourne & Clark case. His deposition in the latter case, taken February 28 and 29, 1916, was incorporated in the record in this case. He there testified that he had refrained from producing proofs of the priority of his invention when called upon to testify in prior litigation in 1911 and 1914 because he wished the priority of his invention to be established by the owners of the patent-the Stone Telegraph Co. and its bondholders-in order to be sure that a bona fide defense would be made. He said that by May 1915, when he testified in the Atlantic Communications Co. case, he had concluded that the owners of the patent were not in a financial position to litigate, and that the Atlantic Co. "would make a bona fide Stone defense." Opinion of the Court. 320 U.S. in question. That reputation, however well-deserved, does not entitle him to a patent for every later improvement which he claims in the radio field. Patent cases, like others, must be decided not by weighing the reputations of the litigants, but by careful study of the merits of their respective contentions and proofs. As the result of such a study we are forced to conclude, without undertaking to determine whether Stone's patent involved invention, that the Court of Claims was right in deciding that Stone anticipated Marconi, and that Marconi's patent did not disclose invention over Stone. Hence the judgment below holding invalid the broad claims of the Marconi patent must be affirmed. In view of our interpretation of the Stone application and patent we need not consider the correctness of the court's conclusion that even if Stone's disclosures should be read as failing to direct that the antenna circuits be made resonant to a particular frequency, Marconi's patent involved no invention over Lodge, Tesla, and Stone. Claim 16 of Marconi patent No. 763,772. The Government asks us to review so much of the decision of the Court of Claims as held valid and infringed Claim 16 of Marconi's patent No. 763,772. That claim is for an antenna circuit at the receiver connected at one end to "an oscillation-receiving conductor" and at the other to a capacity (which could be the earth), containing the primary winding of a transformer, "means for adjusting the two transformer-circuits in electrical resonance with each other," and "an adjustable condenser in a shunt connected with the open circuit, and around said transformer-coil." Marconi thus discloses and claims the addition to the receiver antenna of an adjustable condenser connected in a shunt around the primary of the transformer. The specifications describe the condenser as "preferably one provided with two telescoping metallic tubes separated by a dielectric and arranged to readily |