invention was known in this country. But the date of appellee's discovery relates back to his date of conception, which was prior to Waterman's disclosure of appellant's invention here.

It follows, then, that before the knowledge of appellant's invention here can constitute a bar to appellee's right to his patent, it must operate as a reduction to practice in this country. Any knowledge or use of the invention by appellant abroad, in the absence of a patent or description in a printed publication prior to appellee's date of invention or discovery, cannot deprive appellee of his right to a patent. Rev. Stat. sec. 4923, U. S. Comp. Stat. 1901, p. 3396. All that appellant did abroad was a nullity in so far as it affected the right of appellee. If, therefore, appellee's right is to be destroyed, it must be because of the knowledge imparted to Waterman, which, however complete, amounts to nothing more than proof of conception and disclosure, since all consideration of what appellant did in Europe must be eliminated. The device embodied in appellant's invention had not been constructed in this country at the time appellee filed his application and constructively reduced his invention to practice.

The knowledge sufficient to defeat a patented invention, or the right to a patent for an invention which has been reduced to practice, must be more than mere knowledge of a conception or disclosure of a conception. It has long been held that the representation of the conception of an idea by means of drawings is not such an embodiment into practical and useful form as will negative novelty. It is likewise settled law that an invention cannot be completed by anything short of a reduction to practice. Curtis, Patents, § 87a; Automatic Weighing Mach. Co. v. Pneumatic Scale Corp. 92 C. C. A. 206, 166 Fed. 288, 299; Nelson v. Faucette, 33 App. D. C. 217. Robinson, in his work on Patents, vol. 1, ¶ 227, defines the knowledge sufficient to defeat the right to a patent, as follows: "It is to be remembered, however, that 'knowledge' in this sense, means such an acquaintance with the invention on the part of the public as renders it available to them as a practically opera

tive means. If their knowledge is derived from use in this country, the use must be of such a kind as imparts this information. If it rests on any foreign or domestic patent or publication, these must be sufficient to accomplish the same result. In neither of these cases must there be any necessity for the exercise of additional inventive skill, since, with the employment of the creative faculties, in the adaptation of any invention to the public use, another obligation is incurred which can only be discharged by protecting that inventor in the exclusive use of the invention. Thus we arrive at a more perfect and exhaustive definition of this attribute of novelty, and see that an invention is to be regarded as new whenever it has not already been brought within the practical knowledge of the public as an operative means, either through prior use at home, or through a prior patent or a prior publication."

Knowledge required by the statute is more than a mere mental concept. It must be the result of some act that amounts to invention. "Every invention contains two elements: (1) An idea conceived by the inventor; (2) An application of that idea to the production of a practical result. Neither of these elements is alone sufficient. An unapplied idea is not an invention. The application of an idea, not original with the person who applies it, is not an invention. Hence, the inventive act in reality consists of two acts, one mental, the conception of an idea; the other manual, the reduction of the idea to practice." 1 Robinson, Patents, ¶ 77. No manual act which would amount to a reduction of appellant's idea to practice occurred in this country. Nothing had been done by Waterman and his associates up to the time appellee filed his application which amounted to a reduction to practice. The disclosure of Waterman was that of a foreign invention, of which we can take no cognizance. Hence, for our purpose, the disclosure was nothing more than that of a mental concept. The fact that Waterman gained that concept from what he saw and heard cannot avail appellant to any greater extent than if it had originated with him at the date of Waterman's disclosure. It is a general rule that an invention is reduced to actual prac

tice prior to the filing date only when a mechanical embodiment of it is made in such form as to be capable of practical and successful use. "Reduction to practice must produce something of practical use, coupled with a knowledge, preferably by actual trial, that the thing will work practically for the intended purpose. The conception may give rational hopes of future fulfilment of the purpose at which it aims; but if, as a matter of practice, it falls short of success, it is not a sufficient reduction to practice. Complete invention amounts to demonstration." Sherwood v. Drewson, 29 App. D. C. 161.

In the case of Doyle v. Spaulding, 19 Fed. 744, a patent was assailed on the ground that, before the date of the invention covered thereby, certain persons residing in this country possessed knowledge of such invention, having used it in the city of Sheffield, England, before coming here. Answering this contention, the court said: "After a careful consideration of the provisions of the three sections of the patent act which bear upon the subject (secs. 4886, 4920, and 4923, Rev. Stat.), we are of the opinion that the use, or a knowledge of the use, of an invention in a foreign country by persons residing in this country will not defeat a patent which has here been granted to a bona fide patentee who, at the time, was ignorant of the existence of the invention or its use abroad."

The right of appellee to a patent cannot be superseded by any act of appellant's short of a reduction to practice prior to appellee's filing date. Had his foreign invention been reduced to practice here prior to that date, appellee's conceded lack of diligence would have been sufficient to have entitled appellant to the award of priority; but, inasmuch as his reduction to practice abroad cannot be considered, appellee must be regarded as the prior inventor.

The decision of the Commissioner of Patents is affirmed, and the clerk is directed to certify these proceedings as by law required. Affirmed.

Vol. XXXVII.—21.

Opinion of the Court.

[37 App.

CURTIS v. LINDMARK.

PATENTS; DISCLOSURE; INTERFERENCE; BURDEN OF PROOF; RIGHT TO MAKE

CLAIMS.

1. Where the junior party to an interference, relying for conception and disclosure upon an earlier and rejected application, has copied into his application in interference the drawings of his earlier application, but has added to its specifications, and has also copied into it the claims of a patent granted the senior party, the burden is upon him to show very clearly that he really had a conception of the invention, and disclosed it in his earlier application.

2. Where a party in interference with a patentee suggested in his earlier application the problem which the other party solved, he is not entitled to an award of priority unless in such earlier application he disclosed the means for accomplishing the desired result.

No. 675. Patent Appeals. Submitted May 9, 1911. Decided May 24, 1911.

HEARING on an appeal from a decision of the Commissioner of Patents in an interference case. Affirmed.

The facts are stated in the opinion.

Mr. Richard N. Dyer and Mr. Leonard H. Dyer for the appellant.

Messrs. Harding & Harding and Mr. Frank S. Busser for the appellee.

Mr. Justice ROBB delivered the opinion of the Court:

This is an interference proceeding, and involves a decision of the Commissioner of Patents awarding priority of invention to Tore G. E. Lindmark, the senior party, who is also a patentee. The proceeding originally involved three parties, but the third party, De Ferranti, has taken no appeal.

The invention relates to steam turbines in which the fluid undergoes progressive expansion by the use of devices for heating the fluid prior to its entrance into each of a number of fluid motors. The counts are as follows:

"1. In combination with a plurality of elastic fluid motors wherein said fluid undergoes progressive expansions, means for augmenting the temperature of said fluid prior to each expansion by an amount progressively increasing from the first expansion to the last.

"2. In combination with a plurality of elastic fluid motors disposed in series, means for augmenting the temperature of said fluid prior to entrance to each motor by an amount progressively increasing from the first admission to the last.

"3. In combination with a plurality of elastic fluid turbines in which said fluid is progressively expanded, disposed in series, means interposed between successive turbines for augmenting the temperature of the working fluid by amounts progressively increasing from the initial admission end of the series to the final exhaust."

Lindmark, the senior party, filed an application January 16, 1903, upon which a patent containing the claims of this issue was granted November 1, 1904. Charles G. Curtis filed his present application October 2, 1905. He had previously, on April 8, 1897, filed an application of which he contends the present application is a division. The claims of the earlier application were rejected and it was abandoned October 4, 1905, the present application having then been filed. Curtis here relies for conception on his application of 1897, and the record contains the testimony of experts upon the question whether the present invention was disclosed in that application. The Examiner of Interferences ruled that it was not. The Board of Examiners-in-Chief, two members sitting, while conceding that this earlier application disclosed no means which necessarily would result in the function here claimed, and that. there was a material difference between the apparatus shown by Curtis and the apparatus shown by Lindmark, nevertheless ruled that both the early Curtis application and the applica