Opinion of the Court. 320 U.S. tion, pass through the shunt-circuit thus formed, which shunt includes a portion of the vacuous space within the lamp. This current I have found to be proportional to the degree of incandescence of the conductor or candlepower of the lamp." Edison proposed to use this discovery as a means of “indicating, variations in the electro-motive force in an electric circuit," by connecting a lamp thus equipped at a point where the current was to be measured. The drawings of his patent show an electric circuit, including a filament (cathode) and a plate (anode) both "in the vacuous space within the globe"-an electric light bulb. The shunt-circuit extends from the plate through a galvanometer to the filament. His specifications disclose that the vacuous space within the globe is a conductor of current between the plate anode and the filament; that the strength of the current in the filament-to-plate circuit through the vacuum depends upon the degree of incandescence at the filament; and that the plate anode is preferably connected to the positive side of the current supply. The claims of the patent are for the combination of the filament, plate and interconnecting circuit, including the galvanometer. Claim 5, a typical claim, reads as follows: "The combination, with an incandescent electric lamp, of a circuit having one terminal in the vacuous space within the globe of said lamp, and the other connected with one side of the lamp-circuit, and electrically controlled or operated apparatus in said circuit, substantially as set forth." The structure disclosed in Fleming's Claims 1 and 37 thus differed in no material respect from that disclosed by Edison. Since Fleming's original Claim 1 is merely for the structure, it reads directly on Edison's Claim 5 and could not be taken as invention over it. 1 Opinion of the Court. Fleming used this structure for a different purpose than Edison. Edison disclosed that his device operated to pass a current across the vacuous space within the tube between filament and plate. He used this current as a means of measuring the current passing through the filament circuit. Fleming, in his specifications, disclosed the use of his tube as a rectifier of alternating currents, and in Claim 37 he claimed the use of that apparatus as a means of rectifying alternating currents of radio frequency. But in this use of the tube to convert alternating into direct currents there was no novelty for it had been disclosed by others and by Fleming himself long before Fleming's invention date. On January 9, 1890, ten years before Fleming filed his application, he stated in a paper read before the Royal Society of London: "It has been known for some time that if a platinum plate or wire is sealed through the glass bulb of an ordinary carbon filament incandescent lamp, this metallic plate being quite out of contact with the carbon conductor, a sensitive galvanometer connected between this insulated metal plate enclosed in the vacuum and the external positive electrode of the lamp indicates a current of some milliampères passing through it when the lamp is set in action, but the same instrument when connected between the negative electrode of the lamp and the insulated metal plate indicates no sensible current. This phenomenon in carbon incandescence lamps was first observed by Mr. Edison, in 1884, and further examined by Mr. W. H. Preece, in 1885." Proceedings of the Royal Society of London, vol. 47, pp. 118–9. Fleming's 1890 paper further pointed out that the vacuous space "possesses a curious unilateral conductivity"; that is, it permits current to "flow across the vacuous space from the hot carbon [cathode] to the cooler metal plate [anode], but not in the reverse direction." Id. 122. Opinion of the Court. 320 U.S. He noted the ability of the tube to act as a rectifier of alternating current, saying: "When the lamp is actuated by an alternating current a continuous current is found flowing through a galvanometer, connected between the insulated plate and either terminal of the lamp. The direction of the current through the galvanometer is such as to show that negative electricity is flowing from the plate through the galvanometer to the lamp terminal." Id. 120. Fleming's paper thus noted, contrary to the then popular conception, that it is negative electricity which flows from cathode to anode, but he emphasized that even this had been a part of general scientific knowledge, as follows: "The effect of heating the negative electrode in facilitating discharge through vacuous spaces has previously been described by W. Hittorf ('Annalen der Physik und Chemie,' vol. 21, 1884, p. 90-139), and it is abundantly confirmed by the above experiments. We may say that a vacuous space bounded by two electrodes-one incandescent, and the other cold-possesses a unilateral conductivity for electric discharge when these electrodes are within a distance of the mean free path of projection of the molecules which the impressed electromotive force can detach and send off from the hot negative electrode. "This unilateral conductivity of vacuous spaces having unequally heated electrodes has been examined by MM. Elster and Geitel (see 'Wiedemann's Annalen,' vol. 38, 1889, p. 40), and also by Goldstein ('Wied. Ann.,' vol. 24, 1885, p. 83), who in experiments of various kinds have demonstrated that when an electric discharge across a vacuous space takes place from a carbon conductor to another electrode, the discharge takes place at lower electromotive force when the carbon conductor is the negative electrode and is rendered incandescent." Id. 125-6. 1 Opinion of the Court. Fleming's reference in this publication to the unilateral conductivity of the vacuous space between cathode and anode, and the consequent ability of the two to derive a continuous unidirectional current from an alternating current was a recognition that the Edison tube embodying the structure described could be used as a rectifier of alternating current. This knowledge, disclosed by publication more than two years before Fleming's application, was a bar to any claim for a patent for an invention embodying the published disclosure. R. S. §§ 4886, 4920; 35 U.S. C. §§ 31, 69. Wagner v. Meccano Ltd., 246 F. 603, 607; cf. Muncie Gear Co. v. Outboard Co., supra, 766. It is unnecessary to decide whether Fleming's use of the Edison device for the purpose of rectifying high frequency Hertzian waves, as distinguished from low frequency waves, involved invention over the prior art, or whether the court below rightly held that the devices used by the Government did not infringe the claims sued upon, for we are of the opinion that the court was right in holding that Fleming's patent was rendered invalid by an improper disclaimer. It is plain that Fleming's original Claim 1, so far as applicable to use with low frequency alternating currents, involved nothing new, as Fleming himself must have known in view of his 1890 paper, and as he recognized by his disclaimer in 1915, made twentyfive years after his paper was published and ten years after his patent had been allowed. Its invalidity would defeat the entire patent unless the invalid portion had been claimed "through inadvertence, accident, or mistake, and without any fraudulent or deceptive intention," and was also disclaimed without "unreasonable" neglect or delay. R. S. §§ 4917, 4922; 35 U. S. C. §§ 65, 71; Ensten v. Simon Ascher & Co., 282 U. S. 445, 452; Altoona Theatres v. Tri-Ergon Corp., 294 U. S. 477, 493; Maytag Co. v. Hurley Co., 307 U. S. 243. Opinion of the Court. 320 U.S. We need not stop to inquire whether, as the Government contends, the subject matter of the disclaimer was improper as in effect adding a new element to the claim. See Milcor Steel Co. v. Fuller Co., 316 U. S. 143, 147-8. For we think that the court below was correct in holding that the Fleming patent was invalid because Fleming's claim for "more than he had invented" was not inadvertent, and his delay in making the disclaimer was "unreasonable." Both of these are questions of fact, but since the court in its opinion plainly states its conclusions as to them, and those conclusions are supported by substantial evidence, its omission to make formal findings of fact is immaterial. Act of May 22, 1939, 53 Stat. 752, 28 U. S. C. § 288 (b); cf. American Propeller Co. v. United States, 300 U. S. 475, 479–80; Great Lakes Dredge & Dock Co. v. Huffman, 319 U. S. 293. The purpose of the rule that a patent is invalid in its entirety if any part of it be invalid is the protection of the public from the threat of an invalid patent, and the purpose of the disclaimer statute is to enable the patentee to relieve himself from the consequences of making an invalid claim if he is able to show both that the invalid claim was inadvertent and that the disclaimer was made without unreasonable neglect or delay. Ensten v. Simon Ascher & Co., supra. Here the patentee has sustained neither burden. Fleming's paper of 1890 showed his own recognition that his claim of use of his patent for low frequency currents was anticipated by Edison and others. It taxes credulity to suppose, in the face of this publication, that Fleming's claim for use of the Edison tube with low frequency currents was made "through inadvertence, accident or mistake," which is prerequisite to a lawful disclaimer. No explanation or excuse is forthcoming for his claim of invention of a device which he had so often dem |