(after stating the facts as above). The construction of the claims of the appellants’ patents depends largely upon the question whether or not the inventions are of a primary nature. It becomes necessary, therefore, to consider the prior inventions and the state of the art. On May 27, 1884, A. W. Benson obtained a patent on a well-pipe cutter which exhibits the body provided with an oblique slide or guard, the axle of the perforating-whed traveling therein, and guided thereby into and out of operative position in the same manner as in the appellants’ perforators. The upper end of the slot is at the center of the body of the perforator, and the lower end thereof is toward the periphery thereof, so that as the cutter is moved downward in the slot the periphery of the perforating-wheel is projected beyond the body of the perforator. Bow springs are used as a friction device at the bottom to prevent the movement or turning of the perforator in the well casing. To move the perforator into or out of operative position a screw is used, which projects upward from the slotted piece through a threaded sleeve connected with the wheel carrier by means of a collar.
On April 12, 1898, A. J. Bramlette obtained a patent for a pipe slitter and perforator, which has a body and an oblique slot corresponding with the appellants’ perforators. The oblique slot is so placed that its upper end is at the center of the body, and its lower end at or near *965the edge of the body, so that the downward travel of the axle of the perforator wheel projects the cutter beyond the body and into operating position. A carrier is connected with the axle of the' perforating-wheel, to which is attached a rope or cable leading out of the well. The perforator is lowered into the well to the desired depth, and upon the upward pull of the body the wheel will slide to the bottom of the slot and be brought into operative position. To withdraw the perforator from the well, the rope attached to the carrier will lift the perforating wheel to disengage it from the casing. There is evidence in the record that the Bramlette perforator had been extensively used prior to the time of the Hardison patents, that as many as 500 oil and water wells have been perforated therewith, and that at the time of the taking of the testimony in the court below about 20 well borers were using the same and paying royalty therefor.
Another patent prior to those of the appellants is the Harris patent, issued in 1379, for a device for extracting or splitting tubular casing's of oil wells. In that device a swinging knife is pivoted in the body of the tool, and is so weighted as by gravitation to lie in operative position. To insert the tool in the well casing, the cutter is locked in inoperative position by means of a sliding rod, which catches in a notch therein, where it is held against the tension of a spring. The rod is held up in that position by the frictional device of bow springs at its lower end, which prevents the release of the cutter while it is being lowered into the well casing. When the tool has been inserted into the casing and moved downward to the point where perforations are to be made, the body is drawn upward, the friction device holds the rod stationary, whereby it is disengaged from the knife, and the knife instantly resumes its normal position and is brought into engagement with the casing. The perforation is accomplished by forcing the tool downward until the point of the knife is driven through the casing. The tool may be drawn upward a slight distance, and the body again lowered, and this may be continued to form a series of perforations. The effect of raising the tool is to throw the knife within the body of the carrier and out of engagement with the well casing. It is contended that this invention has no place in the prior art, for the reason that it was intended not to perforate, but to split casings, so as to cause them to collapse in order that they might he drawn from a well; but, as we have seen, it is apparent that it can be used for the purpose of perforating, and as it is furnished with a friction device connecting to a rod which engages the cutter and holds it out of engagement with the casing in lowering the tool into tiie well, and again in throwing it into operative position when the desired point has been reached, it is evident that it is-an invention which is to be reckoned with in ascertaining the prior state of the art.
In these three devices which preceded the appellants’ patents we find all the dements of the appellants’ perforators. In the Benson and the Bramlette patents we find the perforating wheel; the oblique slots guiding the same to and from its operative position. In the Harris and Benson patents we find the use of a frictional device, and in the Harris patent such device is used for the same purpose and in substantially the same manner as in the appellants’ perforators. The ap*966pellants lay much stress upon the automatic feature of their perfora-tors, and contend that Hardison was the first to perfect an automatic tool. But it is clear that the Harris device is automatic in the same manner and to the same degree as those of Hardison. In brief, Hardi-son adopted the friction device of the Harris patent and combined it with the Bramlette patent. He was not the inventor of either a device or a combination that was wholly new, nor did he accomplish a new result. His inventions were mere improvements of what had gone before. They marked an advance in the art sufficient to be patentable and to deserve protection against an infringer who appropriates it or colorably invades it.
We next approach the question of infringement. The issuance of a patent to the appellee creates a prima facie presumption of a patentable difference from the inventions of Hardison. Miller v. Eagle Mfg. Co., 151 U. S. 186, 208, 14 Sup. Ct. 310, 38 L. Ed. 121. The appellee’s perforator adopts the body of the Bramlette perforator, as does Hardison, with the exception that the operation is upon the downward instead of the upward stroke. But the appellee uses no friction device. He uses a coiled spring which in its normal position holds the carrier in operating position. When his perforator is once put in operation, the only part in contact with the casing is the body of the perforating wheel. In the place of a latch to lock the body from sliding down the carrier while being lowered into the well, he uses a catch to hold the carrier from sliding up the body, which it would otherwise do under the tension of the coiled spring; but to release that catch no friction device is necessary and none could be used. The Hardison perforators are put into operation by the tension of the friction device holding against the interior of the well casing and keeping the carrier stationary while the body is being pulled up and away from it. To put the appellee’s perforator into operative position it is necessary only that it impinge momentarily against the bottom of the well. After that is done the rod below the carrier performs no further function, and at no time is frictional contact utilized. But in the Hardison perforators the function of the friction device is continuous and indispensable throughout the operation, and frictional contact with the interior of the well casing is the law of their operation from the time when the perforators are lowered into the well until they are removed therefrom.
Turning, then, to the claims of the Hardison patents, we have to inquire whether the appellee uses the same or similar means and adopts the substantial manner of co-operation of the means. It is contended that claim 1 of each patent is infringed. Claim 1 of the first Hardi-son patent specifies, among other elements:
“A friction device connected with the wheel-carrier to engage the casing t.o temporarily hold the wheel-carrier stationary with relation to the body of the perforator.”
Claim 1 of the second Hardison patent specifies:
“A casing perforator comprising a perforating-tool carrier furnished with a friction device for engagement with the wheel-casing.”
*967In both of these claims the combination is explicitly limited to the use of a friction device which at all times bears upon the interior of the well casing, and at all times governs and controls the action of the perforating -wheel. In the appellee’s perforator, as we have seen, there is and can be no friction device. A mechanical equivalent which may be substituted for an omitted mechanical element in a combination claim is one that performs the same function by applying the same force to the same object through the same means and inode of application. In a combination patent for an improvement in the arrangement or adaptation of old elements, the inventor is not entitled to a broad interpretation of the doctrine of mechanical equivalents, so as to cover a device not specifically included in his claims and specifications. Miller v. Eagle Mfg. Co., 151 U. S. 186, 14 Sup. Ct. 310, 38 L. Ed. 121. Without going further into the specifications of the claims of the appellants’ patents, it is sufficient to say that the combinations, as we have pointed out, limited as they are by the prior state of the art, and explicitly stated as they are in the claims, distinguish the appellants’ from the appellee’s perforators, and the latter, lacking the essential element of the friction device, does not infringe. It is not necessary to inquire whether Hardison has by his claims unnecessarily limited his invention, or whether he might have so worded the same as to cover the combination which was adopted by the appellee. He must be held to the combination which is described and claimed so explicitly. Said Mr. Justice Bradley, in Keystone Bridge Company v. Phœnix Iron Company, 95 U. S. 274, 278, 24 L. Ed. 344:
“When a claim is so explicit, the courts cannot alter or enlarge it. If ibe patentees have not claimed the whole of their invention, and the omission has been the result of inadvertence, they should have sought to correct the error by a surrender of their patent and an application for a reissue. They cannot expect the courts to wade through the history of the art, and spell out what they might have claimed, but have not claimed., ⅞ *- ⅜ But the courts have no right to enlarge a patent beyond the scope of its claim as allowed by the Patent Office, or the appellate tribunal to which contested applications are referred. When the terms of a claim in a patent are clear and distinct (as they always should be), the patentee, in a suit brought upon the patent, is bound by it. Merrill v. Yeomans, 94 U. S. 568, 24 L. Ed. 235. He can claim nothing beyond it. Rut the defendant may at all times, under proper pleadings, resort to prior use and the general history of the art to assail the validity of a patent or to restrain its construction. The door is then opened to the plaintiff to resort to the same kind of evidence m rebuttal; but lie can never go beyond his claim. As patents are procured ex parte, the public is not hound by them; but the patentees are. And the latter cannot shoiv that their invention is broader than the terms of their claim; or, if broader, they must be held to have surrendered the surplus to the public.”
The decree is affirmed.