after stating the case as above, delivered the opinion of the court.
The court below dismissed the bill in this case on the ground that the statement contained in the letters patent upon which this suit is based, that “the invention is in practical operation, and on the market in considerable numbers, and the facts here stated with regard to its operation are such as have been ascertained from commercial experience with it,” proved that the appellant had abandoned the invention. The acts of congress provide that one who has invented and discovered a new and useful improvement, “not in public use or on sale for more than two years prior to his application unless the same is proved to have been abandoned, may, upon payment of the fees required by law, and other due proceedings had, obtain a patent therefor.” 16 Stat. c. 230, p. 201, § 24 (Rev. St. § 4886). The issue of the patent is. therefore, prima facie evidence that the invention it *331protects was not in public use or on sale for more Hum two years prior to the Fling of tlie application on which it is based, and that it was not proved to be abandoned. The utmost effect of the recital in the juitent which we have quoted could not carry it further than to show that within twro years prior to the application the improvements described in i t liad been used and sold. But the use and sale of the invention within two years before the application for the patent was filed was not sufficient to establish an abandonment of the invention, because the act of congress expressly authorizes the issue of a patent notwithstanding such use and sale. An abandonment may undoubtedly be proved within two years prior to the filing of the application, but it ought not to be presumed, and it should be established by convincing evidence of the intention of the owner of the invention to dedicate it to the public. An abandonment is a dedication, and, like any other dedication, it should be clearly proved. It rests upon the intention of the inventor. If he expressly declares, or by his.acts clearly shows, his intention to dedicate his invention to the public, a finding of abandonment would be warranted. But such a dedication should not be lightly presumed, because it surrenders a vested right of property as much as the dedication of land for a xmblic park or a public road. The evidence in this case does not satisfy us that the appellant., or the inventor, Martin, its assignor, ever had any intention to dedicate this improvement to the public. Under the acts of congress, they were authorized to use and sell the invention for twro years, and to apply for and receive their patent, so that their failure to apply during that time was not inconsistent with an intention to preserve and protect their rights. There is no evidence in the record of a use or sale of the invention more than two years before the application was made. There is no evidence of an express declaration that the inventor or the appellant would not', or did not intend to, apply for a patent for it, and there is no evidence of any acts inconsistent with such an intention. On the other band, the application for the patent within two years after the invention was made was presumptive evidence of an intention not to dedicate it to the public, and the issue of the patent was prima facie proof that it had not been abandoned. Moreover, the defense of abandonment was not pleaded, and the appellant had no opportunity to meet it by evidence. It was discovered by the court below at the final hearing, and it rested on the statement in the patent which we have quoted, and on that alone. That statement was insufficient to support it. 'Mere forbearance to apply for a i>atent until one has perfected bis invention, and tested it by actual practice, affords no just ground to presume its abandonment; nor will the use or sale of it within two years before the application is filed afford such ground, unless such use or sale is accompanied by other acts or by declarations which clearly evidence an intention to dedicate the improvement to the public. Agawam Co. v. Jordan, 7 Wall. 583, 607; Adams v. Jones, 1 Fed. Cas. 126, 127 (No. 57); Babcock v. Degener, 2 Fed. Cas. 293, 297 (No. 698); Jones v. Sewall, 13 Fed. Cas. 1017, 1027 (No. 7,495); M’Millin v. Barclay, 16 Fed. Cas. *332302, 306 (No. 8,902); Pitts v. Edmonds, 19 Fed. Cas. 751, 757 (No. 11,191).
In considering the merits of the case, the defenses of prior use and no utility may be dismissed without extended consideration. All the witnesses on both sides of the case testify that the combination of the internal-toothed spur-wheel with, the pinion and the other usual machinery of a' windmill and pump is more useful and more A-aluable than any other combination of elements in a windmill and pump yet discovered. The evidence of prior use is the testimony of a single witness, who was once in the employ of another infringer of the device of the appellant, but has since been employed by the appellee. He produces no part of the old windmill which he testifies was set up and put in operation before Martin filed his application, and his evidence is without the support of any patents or exhibits, and without the support of the testimony of any other witness. The unsupported oral testimony which wall warrant a finding of prior use should be clear and satisfactory. It is always open to suspicion. It ought to be sufficient to establish such a use bevond a reasonable doubt. The Barbed-Wire Patent, 143 U. S. 275, 12 Sup. Ct. 443, 450; Deering v. Harvester Works, 155 U. S. 286, 300, 15 Sup. Ct. 118. The testimony for the appellee on this issue is not of this character, and it will be dismissed without further comment.
But the appellee denies infringement. The essential element of the combination which the inventor sought to protect by the first claim of the patent in suit was the internal-toothed spur-wheel or spur-gear meshing with and driving the pinion which actuated tin1 pitman and pump-rod. Prior to his invention, all windmills had been driven by external-toothed spur-wheels. As the cogs on the spur-wheel and pinion and the other parts of the machinery wore away, the spur-wheel and the pinion drew ajwu’t, and as the pitman-connection passed over the center, and the motion changed from a pulling to a pushing one, or vice Arersa, a pounding and racking of the machinery arose, which shortened its life, and sometimes stripped the cogs from the pinion. The object of .Martin’s invention avus to do away with this pounding, and to prevent this Avear and strain of the machinery. He accomplished this by throw-in g aside the external-toothed spur-gear, and combining an internal-toothed spur-wheel with the pinion and the other necessary elements of'the Avindmill, so that, as he says, “a plurality of the pinion-teeih are always engaged with the internal spur-gear, resulting in giving a perfectly uniform and smooth and noiseless reciprocating motion to the actuating-rod, thereby prolonging the life of the machine by saving it from constant jarring, and preventing wear and tear.” The evidence is undisputed that this invention completely accomplished its purpose. In the year 1893 or 1894 the appellee discarded the external-toothed spur-gear, with which it had previously driven its windmills, and substituted in its mills the internal-toothed spur-wheel described and claimed by Martin. The record discloses the fact that the president of the appellee had previously seen one of the mills of the appellant in operation, and that he was advised to make this change by his pat*333tern-maker, who bad been in the employ of an infringer upon the appellant, against whom it had procured a decree, because the pattern-maker thought that the internal-toothed wheel was a good thing. The appellee seeks to escape from the inevitable conclusion to which these facts lead on the plea that it does not use the pitman-bar, the wrist-pin, or the pivoted pitman described in the specification and in the second and third claims of Martins patent. Its counsel invokes the principle that there can be no infringement of a combination if any element of the combination is absent from the infringing device, and insists that the absence of the pivoted pitman and of the pitman-bar Is fatal to the appellant’s claim of infringement. The answer is that this invention consists essentially, as the inventor declares at the beginning of his specification, in the combination of the internal-toothed spur-gear with any suitable pinion, wind-shaft, wrist-pin, pitman, and pump-rod of a windmill, and that he has broadly claimed this combination in the first claim of his patent. That claim is:
“(1) The combination, with a windmill-driving shaft and a x>mion thereon, of an internal-toolhed spur-wheel mounted adjacent to the said shaft, and, meshing with said pinion, a pitman connected with the spur-wheel, and an aetuating-rod connected with the pitman.”
There is not an element in this combination which is not found in the windmill of the appellee, and it cannot he permitted to read other elements into this claim, and then io defeat it, because it does not use the elements it interpolates. The pitman-bar and the pivoted 'pitman were omitted from this claim, we think, for the express purpose of securing the essential element of the invention in combination with any pinion, pitman, and pump-rod that might be used. In our opiniou. the special office of the second and third claims was to secure combinations containing the pivoted pitman and the pit-man-rod described in the specification and omitted from the first' claim, and the fact that these claims were added is a very persuasive argument that the additional elements they protect were not secured by the first claim. Any construction which would read into the first claim these additional elements renders it useless and unmeaning, because it gives it (be same effect as the claims which, follow it, and in this way shows that neither the patentee nor the patent office contemplated such an interpretation. The appellee has appropriated the essential feature of this invention, — the internal-toothed spur-gear in combination with the pinion, pitman, wind-shaft, and punap-rod of a windmill. ’The terms of the first claim of the patent are plain and unambiguous. They need no construction, and, when taken in their ordinary signification, they fully describe and clearly claim the combination which the appellee is using. It ought not to escape here, because it does not use subordinate or unimportant elements of combinations described in other claims, which were undoubtedly omitted from this claim that the inventor might more perfectly secure the essential element of his invention. Manufacturing Co. v. Wharton, 28 Fed. 189, 190; Tondeur v. Stewart, Id. 561, 564; Coupler Co. v. Pratt, 70 Fed. 622, 629.
Finally, the counsel for the appellee argue that there is no patentable novelty in the combination described in this claim, because in*334ternal-toothed spur-wheels were old and well known, and the substitution of them for external-toothed spur-gear in the machinery of windmills was nothing but a double use.' This argument is always plausible and persuasive where old elements have been combined to produce a new or better result. Each element, taken by itself, has its old effect, and it is always difficult- to understand how it was that the practiced eyes of skilled mechanics did not at once see and apply the necessary remedy to the troublesome evil -which the invention removes. The fact, however, that such an evil long existed, and that no mechanic perceived or applied the remedy, is the most conclusive evidence that.something more than his eyes and skill was required to discover and apply the requisite device. It is true that internal-toothed spur-wheels, their effect and their relative advantages over external-toothed wheel's had been familiar to mechanics time out of mind. They had been used on mowing machines and harvesting machines, on machines for sawing wood, and doubtless upon hundreds of other machines, but no one had ever combined one of these internal-toothed wheels with the pinion, pitman, and pump of a windmill until Martin made his invention in the year1 1889. Windmills were old, and their operation was familiar to mechanics, but until that year they went on pounding their wheels with every stroke of the pump-rod, wearing themselves out prematurely, and occasionally stripping their pinions of cogs for the lack of the combination of this internal-toothed spur-wheel with the other essential elements of their machinery. If naught but the skill of the mechanic was required to make this improvement, it is passing strange that no mechanic ever made it until after Martin discovered and described it. In Electric Co. v. La Rue, 139 U. S. 601, 11 Sup. Ct. 670, the supreme court sustained a patent to one who took a torsional spring, such as had been used in clocks, doors, and other articles of domestic furniture, and applied it to telegraph instruments. In Crane v. Price, Webst. Pat. Cas. 409, the use of anthracite coal where bituminous coal had previously been used for smelting iron was held to be an invention, because it produced better iron at less expense. It is not infrequently a difficult and delicate task to determine vdiether or not the application of an old device to the production of a new or better result rises to the dignity of an invention. Mr. Justice Brown says in C. & A. Potts & Co. v. Creager, 155 U. S. 597, 608, 15 Sup. Ct. 194, 198, that the result of the authorities upon this subject is that, “if the new use be so nearly analogous to the former one that the applicability of the device to its new use would occur to a person of ordinary mechanical skill, it is only a pase of double use; but if the relations between them be remote, and especially if the use of the old device produce a new result, it may at least involve an exercise of the inventive faculty.” The best evidence that the apjdication of the internal-toothed spur-wheel to the new use of propelling the machinery of a windmill would not occur to a person of ordinary mechanical skill is that it did not occur to any of them in all the years in which windmills had been in use before Martin discovered and applied it. Thomson v. Bank, 10 U. S. App. 500, 512, 513, 3 C. C. A. 518, 522, 523, 53 Fed. 250, 255; Loom Co. v. Higgins, 105 U. S. 580, 591; Consolidated Safety-Valve *335Co. v. Crosby Steam-Gauge & Valve Co., 113 U. S. 137, 179, 5 Sup. Ct. 513; Magowan v. Packing Co., 141 U. S. 332, 341, 342, 12 Sup. Ct. 71; The Barbed-Wire Patent, 143 U. S. 275, 281, 283, 12 Sup. Ct. 443, 450. Moreover, the combination of Martin immediately went into general use. More than 3,000 windmills which contain his combination have been manufactured and sold since 1890. All the witnesses testify to its advantages over the old combination which contained the external-toothed gear, and the fact that the appellee discarded the latter, and substituted the former, demonstrates its utility and ils advantages. Where the question of novelty is in doubt,'the fact (hat the device has gone into general use, and has displaced other devices previously employed for a similar purpose, is sufficient to turn the scale in favor of the invention. C. & A. Potts & Co. v. Creager, 155 U. S. 597, 609, 15 Sup. Ct. 194; Smith v. Vulcanite Co., 93 U. S. 486; Magowan v. Packing Co., 141 U. S. 332, 343, 12 Sup. Ct 71.
The probative force of Hie patent, and of the facts to which we have adverted, constrain us to hold that the combination described in its first claim rose to the dignity of an invention, and was properly secured by the patent. The decree below must be reversed, with costs, and the case must be remanded to the court below, with directions to enter a decree to the effect that the first claim of the patent is valid, and is infringed by the appellee; that the latter be enjoined from making, using, or selling any machine containing the combination described in that claim; and that it account for the profits which il lias derived from the manufacture and sale of any such machines; and it is so ordered.