We are required in this case to determine the validity of claims numbered 11, 12, 13 and 14 of letters patent No. 1,716,962, granted on June 11, 1929, to Harry L. Johnson for invention in a 'water propulsion device'. Respondent Johnson Brothers Engineering Corporation is the owner of the patent, and respondent Outboard, Marine & Manufacturing Company, is the exclusive licensee thereunder. Petitioner Muncie Gear Works, Inc., manufactured outboard motors which are claimed to infringe, and petitioner Bruns & Collins, Inc., sold them.

Respondents contend that this as a validly issued patent covering an invention which solved the problems of 'cavitation' by relatively large and fast outboard motors. 'Cavitation' is the drawing of air by the propeller from above the surface of the water to the propeller itself. Air so drawn reduces the propulsive effect of the propeller and causes 'racing' of the motor with consequent risk of its disintegration and danger to the user. Increased speed or power entails a greater tendency to cavitate. Cavitation may be diminished by setting the propeller deeper in the water, but this increased projection increases resistance and retards speed.

Long before the patent in question, it was known that cavitation could be controlled, and in practice it was controlled, in at least all but relatively large and fast outboard motors, by setting a flat plate horizontally above the propeller and beneath the surface of the water, to act as a baffle and prevent the propeller from drawing air.1 Respondents presented expert testimony to the effect that relatively large and fast water-cooled outboard motors cannot be successful unless they embody the asserted invention which respondents say is the subject matter of the claims in question. In general, this may be said to consist in the use of an anti-cavitation plate on a housing for the engine and propeller shafts enclosing the water passages for the cooling system, shaped both above and below the plate so as to reduce water displacement and resistance and thus to reduce or eliminate eddy currents forming vortexes through which air can be sucked into the propeller. This permits adequate control of cavitation by means of a not unduly large anti-cavitation plate.

Harry L. Johnson, an experienced engineer and manufacturer of outboard motors, filed his application for the patent on August 25, 1926, but it in no way suggested the combination now asserted as his invention. The single sheet of drawing accompanying the application was not changed during the prosecution of the application, and is the same as the drawing of the issued patent. This drawing showed an outboard motor assembly comprising, among other things, an engine at the top connected with a propeller at the bottom, with an anti-cavitation plate located horizontally above the propeller approximately midway between top and bottom of the housing for the engine and propeller shafts. All water passages for the cooling system beneath the normal water level were shown to be enclosed in the housing. No cross section of this housing was drawn or indicated, and for all that appears from the drawing it might have been circular, triangular or rectangular. The drawing showed an arched member extending from the housing and anti-cavitation plate over the top and to the rear of the propeller, containing openings and passages for the intake and discharge of water, and ending in a curved 'deflection plate' extending rearwardly like a fixed rudder. From the specifications and claims it appeared that the purpose of the deflection plate was to compensate for the side an pivotal force of the moving propeller, which tended to draw the boat off its course unless the operator made constant adjustment to offset the 'side throw.' The specifications and drawings both indicated an anti-cavitation plate which the specifications said 'prevents cavitation,' but it was in no way asserted that the cavitation plate was new, or that it was being employed in any novel cooperative relation to the other elements.

All of the claims of the application as originally made were rejected on December 15, 1926. On December 13, 1927, Johnson offered amendments which retained and amended the prior claims and added others directed to the feature of the deflection plate. In urging allowance, he said, among other things: 'It is conceded that cavitation plates are old in the art as shown in the patent to Johnson cited,' and he proceeded to urge as an invention the combination of the cavitation plate and the arching member of reflection plate. A similar supplemental amendment was filed on January 19, 1928. Several of the original claims as amended were allowed, and the rest of the claims rejected, on June 7, 1928.

On December 8, 1928, Johnson came forward with new claims. Claims 20 to 25 offered by this amendment made no mention of the deflection plate or of the arching members, but did not even suggest the presently asserted invention. On March 30, 1929, Johnson cancelled these claims and offered further amendments to his original application, together with a supplemental oath that he had invented the subject matter of the application as so amended, prior to the filing of the original amendment.2 The effect of those changes was aptly described by the patent examiner: 'The amendments have been such that the claims now emphasize the anticavitation plate rather than the anti-torque plate.' With changes which are immaterial here, the new claims so offered became the claims in issue. In them Johnson for the first time made claims relating to the exterior surface of the housing. Claim 12 described the housing as having 'unbroken outer wall surfaces at each side,' and claim 14, as having 'smooth and unbroken walls.' Claims 11 and 13 were silent on the subject. The amendment also set forth an addition to the description which was incorporated in the description of the patent as issued. Here we find the expression 'relatively smooth and substantially stream-line surfaces.' Other than these, no indication of the nature of the surface or cross section of the housing was given at any time during the prosecution of the application.

The petitioners interposed defenses to all of the eight patents upon which respondents sued them in the District Court for the Northern District of Illinois, Eastern Division3 which we take to have put in issue the question whether the claims were void because made more than two years after the first public use of the device.4 At the trial two of the officers of respondent Outboard, Marine & Manufacturing Company testified on direct examination as respondents' witnesses to the effect that in January or February of 1926 one of this respondent's predecessors put on the market licensed outboard motors equipped with smooth-walled housings, anti-cavitation plates, and internal water passages as described in the claims in suit; and that at least one competitor (which was also a predecessor) had brought out a substantially similar, but unlicensed, motor about a year later.5

In an unreported decision the District Court did not touch on this question, but found as a matter of fact and of law that the claims in question were invalid because merely aggregational. On appeal to the Circuit Court of Appeals the issue of sale or public use was not clearly presented,6 if indeed it was presented at all; and the opinion rendered by that Court did not advert to it, although it held that the claims here involved were valid and infringed. 7 Cir., 119 F.2d 404. While there was no conflict of decision with respect to these claims,7 we granted certiorari in view of the questions presented and because the patent dominates a substantial portion of an industry so concentrated in the Seventh Circuit that litigation in other circuits, resulting in a conflict of decisions, is unlikely. 314 U.S. 594, 62 S.Ct. 100, 86 L.Ed. —-. Schriber-Schroth Co. v. Cleveland Trust Co., 305 U.S. 47, 59 S.Ct. 8, 83 L.Ed. 34.

Section 4886 of the Revised Statutes, as amended and applicable to the present case, provided for the issuance of a patent to an inventor upon certain conditions, one of which was that his invention was 'not in public use or on sale in this country for more than two years prior to his application.'8

In an effort to avoid the effect of this provision, respondents contend that the question of its applicability was not raised either in the District Court or in the Circuit Court of Appeals; that there was no opportunity to meet the issue; and that the invention as finally claimed was disclosed by the application as originally made or in any event as amended on December 8, 1928.

However, the evidence of public use and sale, given as we have pointed out, by respondents' own officers and witnesses,9 has not been questioned or contradicted, and is interpreted by respondents' counsel in accordance with our view of it. In their brief they say 'It is true that after Johnson Motor Company, licensee under the patent in suit, had popularized devices embodying the subject matter of the claims in suit, at least one competitor copied the combinations of the claims in suit from the Johnson motor before claims closely resembling those in suit were presented to the Patent Office in December 1928. This was done by Lockwood Ash Motor Company, then a competitor, but subsequently merged to constitute a predecessor of Respondent, Outboard, Marine & Manufacturing Company. * * * Lockwood Ash first adopted this combination for the 1927 season. The model year commenced in January or February. * * * Concededly, the original claims were limited additionally either to the deflection plate or to the arched support. But claims without these limitations had, contrary to Petitioners' assertions, been filed December 8, 1928. The difference in date is critical because the record shows that the only manufacture of devices embodying the invention which had occurred more than two years prior to December 8, 1928, was licensed manufacture by Johnson Motor Company, predecessor of Respondent Outboard, Marine & Manufacturing Company, and in 1926, exclusive licensees of Respondent Johnson Brothers Engineering Corporation, owner of the application for the patent in suit. * * * The only concern which produced outboard motors in accordance with the invention of the patent in 1926 was the exclusive licensee under the application for the patent in suit. * * * March, 1929, would be more than two years after the opening of the 1927 model year; but the actual date in December, 1928 when the patentee claimed the specific invention in controversy, without regard to deflection plate or arched support, was well within two years of the first competitive use of the invention, even assuming that the two year period is of any significance in the present case. * * *'

It is clear to us, however, that the amendments of December 8, 1928, like the original application, wholly failed to disclose the invention now asserted.

The claims in question are invalid if there was public use, or sale of the device which they are claimed to cover, more than two years before the first disclosure thereof to the Patent Office. Cf. Chicago & N.W. Railway Co. v. Sayles, 97 U.S. 554, 557, 559, 563, 564, 24 L.Ed. 1053; Schriber-Schroth Co. v. Cleveland Trust Co., supra, 305 U.S. at page 57, 59 S.Ct. at page 12, 83 L.Ed. 34. Section 4886 of the Revised Statutes would in terms provide for their invalidity had they been offered by application rather than by amendment; and whatever may be the efficacy of an amendment as a substitute for an application, it surely can effect no more than the application itself.

We think the conclusion is inescapable that there was public use, or sale, of devices embodying the asserted invention, more than two years before it was first presented to the Patent Office. We are not foreclosed from a decision under Section 4886 on the point by the obscurity of its presentation in the courts below. This issue has been fully presented to this Court by the petition for a writ of certiorari, and in subsequent briefs and argument; and there is not the slightest indication that respondents have been prejudiced by such obscrity. To sustain the claims in question upon the established and admitted facts would require a plain disregard of the public interest sought to be safeguarded by the patent statutes, and so frequently present but so seldom adequately represented in patent litigation.

We therefore hold that the claims in question are invalid under Section 4886 of the Revised Statutes, and accordingly have no occasion to decide any other question in the case.

Reversed.