after making the foregoing statement, delivered the opinion of the court.
Our conclusion is that the court below was right in deciding “that, in view of such limitations as ought to be put upon the complainants’ patent, the defendant’s device does not infringe.” It would be impossible, within the reasonable limits of an opinion, to follow counsel through hundreds of pages of brief in the discussion of the evidence found in the three large volumes which constitute the printed record. We content ourself with a presentation of propositions which are thought to determine the merits of the appeal.
*173The first claim, though not in issue, it is to be observed, does not include the lever, I, and connects the spring-sheave with the chain “between the lever and the hinge-bar.”
The second claim includes expressly the lever, I, and other parts, designated by letters, except the spring-sheave, B, which is included by implication only, if at all. The implication, if admissible, may arise from the requirement that the chain, E, have “a yielding support,” and that there shall be a “mechanism for adjusting the chain and securing it in any desired position.” “A yielding support” for the chain, it is evident, might be found in other forms than the spring-sheave described. It might be simply a wheel, or a pulley; but, in order both to support the chain and secure it in any desired position, the spring-sheave, with its sprocket projections, and the lever, G-, or the full equivalents thereof, would seem to be necessary. That this claim is not infringed is clear, not only because the “mechanism for adjusting the chain and securing it in any desired position” is not to be found in the defendant’s machine, but because there is nothing in that machine which can be adjusted, and so held, as to operate like the chain of the patent in suit. That chain is adjusted and held in position not solely by the lever, G, called the adjusting and lifting lever, but also by the action of the spring-sheave and its sprocket projections, the combined result of which is, as stated in the specification, that “it [the spring-sheave] does not interfere with the direct action of the lever, G-, in raising and lowering the finger-bar and in sustaining it at the proper height; for, since it is coupled to the chain, E, between the said lever and the hinge-bar, it acts freely to balance and lift on the finger-bar, thereby rendering the draft of the same light, the' part of the chain between the sheave and the lever, G, allowing a slack as well as a taut chain while the machine is at work; but at the same time the finger-bar is firmly sustained all the time by ihe lever, (I, just the same as if the spring-sheave were not applied at all.” There are here features of construction, adjustment, and operation which not only cannot be found in the machine of the defendant, but cannot be introduced without a reconstruction which would destroy its identity. The chain, either slack or taut, between the spring-sheave and the adjusting and lifting lever, G, with its segment, H, and the consequent effect upon the operation of the entire mechanism, are the characteristics which must have been deemed to make the combination patentable.
The third claim is a specific one for the combination of the parts designated by the letters E, B, I, andL, “operating together, substantially as and for the purpose herein described.” The hinge-bar, F, is not mentioned, and can be included only by implication. Is the implication necessary or justifiable? The lever, 1, to be anything more than a prolongation of the chain, must, of course, have a fuicrum; but that might be provided in many ways. It might, for instance, be a fixed pivot secured to the frame of the machine, or a pivot supported by springs or otherwise, so as not to be rigidly fixed and unyielding, and, on that account:, perhaps better adapted to serve its purpose. It is therefore to be presumed that the claim was not intended to be *174restricted to the hinge-bar, F, but to include any form of fulcrum which might be found available; that is to say, any form which would enable the parts mentioned to “operate together substantially as and for the purpose specified.” Anything less would not meet the requirements of the claim. If a fulcrum cannot be supplied by implication, the claim is perhaps void, because it does not show an operative device; but that the hinge-bar, F, expressly included in the second claim, cannot be read into the third, where it is not mentioned, seems to be clear. In McCarty v. Railroad Co., 160 U. S. 110, 116, 16 Sup. Ct. 240, 242, it was suggested that a feature of construction described in the specification should be read into the claims for the purpose of sustaining the patent, but the court said:
“While this may be done with a view of showing the connection in which a device is used, and proving that it is an operative device, we know of no principle of law which would authorize us to read into a claim an element which is not present, for the purpose of making out a ease of novelty or infringement. The difficulty is that, if we once begin to include elements not mentioned in the claim, in order to limit such claim and avoid a defense of anticipation, we should never know where to stop. If, for example, a prior device were produced, exhibiting the combination of these claims plus the springs, the patentee might insist upon reading some other element into the claims — -such, for instance, as the side frames, and all the other operative portions of the mechanism constituting the car truck — to prove that the prior device was not an anticipation. It might also require us to read into the fourth claim the flanges and pillar's described in the third. This doctrine is too obviously untenable" to require argument.”
So bere, if it be conceded, on grounds of necessity, that the hinge-bar, F, is to be included in the claim, it is equally necessary, in order that the parts named shall operate, together with that bar, “substantially as and for the purpose specified,” that the lifting-lever, G-, be also included. Indeed, that lever, as an auxiliary to the spring-sheave, is more important to the complete accomplishment of the declared purposes of the invention than is the hinge-bar, F, which, as we have seen, could be substituted by other means. “This,” says the specification, “is an important feature, since the spring-sheave could not be relied on of itself to sustain the finger-bar, and prevent its plunging into the. ground on meeting an obstruction. * * * When the forward end of the chain is secured to the lever, G-, or its segment, the whole device is complete, and ready for operation.” To demonstrate this, it is only necessary to refer to the perspective drawing intended to show equivalency between the bell-crank lever found in the defendant’s machine and the spring-sheave in the Smith patent, from which, it will be observed, the lever, <3-, is omitted. But for the present purpose let it be assumed that the third claim does not include that lever, or its equivalent. So construed, the claim is for the combination of .the lifting-chain, E, the spring-sheave, B, the lever, I (having for a fulcrum the hinge-bar, F), and the finger-bar, L, operating together substantially as and for the purpose stated, in so far (it must be further implied) as they may so operate without the aid of the lifting-lever, GL The several parts named, even if operative without the lever, are not in the appellee’s machine. The parts which are found there are not approximately equivalent,' nor are they combined and *175adjusted, or capable of being combined and adjusted, so as to operate substantially in the same way. "
We are of opinion, further, that the reasoning by which it has been sought to show equivalency between the McCormick machine and that of the patent will establish a like equivalency for the parts and combination of the “Advance Mower”; and, that done, the patent falls by reason of anticipation. If the spring of the McCormick machine tends to support the finger-bar, there is a like tendency, perhaps not so strong, but of the same character, in the spring of the Advance machine. Neither of them, as adjusted, can be said to be “of sufficient strength to nearly counterbalance the weight of the finger-bar and its appendages.” The idea of sustaining the finger-bar by means of a spring connected with the frame of a moving machine was not new or patentable in 1880. The support would necessarily be at the shoe, near the frame; and, in order at the same time to sustain the outer end of the bar, it was necessary to apply a force at the inner end or heel; but that, too, was a simple operation, and, in view of well-known devices, could not have involved invention unless in the means employed. Patentability need not be denied to Smith’s mechanism, but in a field of invention so narrow a combination like that of the patent could be entitled to only a limited range of equivalents. If it be said that the Advance mower was not an anticipation because the reflex bearing of its spring on the heel of the finger-bar was trifling, and not thought of, or in contemplation by, the maker or the patentee, for the same reason the McCormick machine, if.it had antedated the Smith patent, would not have been an anticipation. The spring of the Advance machine must always have had some bearing on the heel of the finger-bar (the evidence shows in one experimental instance 12 to 20 pounds); and though it is perhaps, but not certainly, true that the McCormick spring has a somewhat greater force of bearing, it is not otherwise essentially different; and if, for such reason, it would not have been an anticipation, for the same reason it is not an infringement. Excepting the spring-sheave, the entire conception of the Smith patent is embodied in the Advance machine, against which the most that can be said is that the spring there shown is weak; but plainly invention was not required to strengthen and so adjust it as to make it effective, like the McCormick spring, for instance, if that is in fact more effective.
Judge SI 10WALTER sat at the hearing of this case, and, some months before his death, had prepared an opinion to the effect that the third claim of the patent is valid, and had been infringed. So much of the opinion as relates to that claim, omitting cuts which appear in the opinion of the court, is as follows:
The hinge-bar, F, is not expressly named as a factor in the third claim. A serious question arises whether, in view of cases such as Torrant v. Lumber Co., 30 Fed. 830, this claim ought not to be held void as being for an inoperative combination. But the piece marked “I” in Fig. 2 cannot be the “lever, I,” without a fulcrum. That ful*176crum must be supported, and the binge-bar, F, with its pivots at either end is the support. If«the parts or factors expressed in the claim are to have the quality, as also stated in the claim, of “operating together * * * as * * * specified,” and “for the purpose * specified,” then we must understand the hinge-bar, F, to be part of- the combination. It is my opinion * * * that this construction may, in view of the specification and of the language last quoted from claim 3, be given to that claim. This was substantially the understanding of Judge Acheson, of the Third circuit, as expressed in a former litigation concerning this patent. Manufacturing Co. v. Deering, 40 Fed. 87. We may add that this construction is not disputed by- the learned counsel for appellee, oí by its accomplished expert, Mr. See, — assuming that the opinion of an expert witness is competent upon such a question. The mechanism of the third claim is the spring fastened at one end to the frame of the machine, namely, the stationary spindle upon which the sheave turns, and at the other to the periphery of the sheave; and combined .with this spring by means of the sheave is the chain, secured at one end on the sprocket projections of the sheave, and at the other to the extremity of the long arm of lever, I, which lever is fulcrumed on the hinge-bar, and has its short arm bearing on the inwardly projecting end of the finger-bar. By force of the spring, the sprocket projections pull, through -the chain, upward on the long arm of the lever, and thus support a portion of the weight of the hinge-bar and lever and of the finger-bar throughout its length. If, instead of the flat, coiled spring in the sheave, a helical spring be fastened at one end to a point immediately above the center, and at or near the periphery of the sheave, and at the other to a forward portion of the frame of the machine, said helical spring, being tense between said points, would obviously have the same function in pulling upward on the chain, E, as the flat, coiled spring of the patent. The combination of the third claim appears to be faithfully shown in the following diagram [supra]. If to the sprocket projection horizontally in the rear of the spindle the chain be attached, and to the one vertically above the spindle the rear end of the helical spring be attached, then the coiled spring may be taken out from the sheave, and the forward half and the lower quadrant of the remaining half of the sheave may be cut away, as may also be the portion of the upper rear quadrant between the two named sprocket projections. There will remain, in effect, two spokes,— one horizontal, the other perpendicular, — forming a bent lever ful-crumed at the angle around the spindle. The chain, as said, will be attached at the end of the rearwardly projecting horizontal arm; the spring, at the end of the perpendicular arm. With what is thus left, of the sheave, and with the helical spring fastened at one end to the frame, instead of the coiled, flat.spring so fastened at one end, the action of the combination in sustaining the finger-bar will be substantially the same as before. The following diagram shows, in effect, those portions of the appellee’s machine alleged to infringe the claim now in question:
*177
The flnger-bar, L, hinge-bar, P, and lever, I, of the patent in suit are here duplicated. The link, E, replaces the chain, E, of the patent in suit, the bell-crank lever replaces the sheave, and the helical spring —very strong in appellee’s machine, and stretched about to the limit —replaces the flat, coiled spring of the patent. The spring in appel-lee’s machine, as here illustrated, pulls from a fixed point on the tongue; the flat, coiled spring in the machine of the patent from a point on the spindle of the sheave, which, as already noted, is also fixed as a part of the frame of that machine. The combination used by appellee seems to be substantially identical in result and mode of operation with the third claim of the patent in suit, as well illustrated by the following diagram. [This reference is to the diagram designed to show “equivalency of bell-crank lever and sheave,” supra.] It is insisted hy counsel for appellee that, when the machine complained of is in operative adjustment, — as shown in the two diagrams, —-the spring does not exert any substantial force to raise the forward arm of the bell crank whereljy the link, E, is made to pull on the long arm of lever, I. The third or perpendicular arm of the bell crank in appellee’s machine is extended upward in the form of a handle to be worked by the driver in raising the finger-bar and hinge-bar out of operative position, — a process analogous to one obvious use of the lever, G-, in the machine of the patent. In the case of each machine it will be noticed that the spring strongly aids this lifting action of the hand-lever. Counsel for appellee insists that the helical spring merely sustains the handle, G-, the link, E, and the lever, I, so that rattling is prevented, but without pressure on the heel of the flnger-bar sufficient to affect its action to any degree; and that, *178apart from this slight tension to prevent rattling, the function of the helical spring is to aid the driver in raising the finger-bar and hinge-bar from the ground, and entirely out of operative position. Touching the actual lifting effect of the helical spring, the record contains a mass of testimony more or less contradictory concerning weighing tests made when the spring was in' place and when it was detached. Without analyzing this testimony and the varying conditions of these tests and of the machines subjected to the same, it would seem entirely certain, on the mechanical principles obviously involved, that the helical spring of appellee’s machine is functional in sustaining to a very substantial degree the finger-bar when that machine is in operation. That spring, as already noted, is very strong, and, when the machine is working, very tense. Without going at large into the mechanical principles of the lever, the model of appellee’s machine introduced in evidence shows that a straight line drawn from the center of the pivot of the' bell crank at right angles to the direction of the forward arm and downward to the central longitudinal line of the stretched spring will be in length about one-third the distance from the bell-crank pivot to the point where the link is attached at •the end of the forward arm. This is the position when the machine is working. The upward pull of the forward arm on link, E, ought, therefore, to be something like one-third of the force exerted horizontally by the stretched spring. In one form of machine used by appel-lee the forward end of the spring is held on the lower extremity of a lever bent to an angle, pivoted at the angle on the tongue, and with its upper arm bearing against an upright piece, which latter is again pivoted at its lower end on the tongue forward of the bent lever pivot, and connected at its upper end, by what is called a connecting link, with the lever, G-, at a point above the pivot of said last-named lever. The continuous lifting force of the spring, since it is counterbalanced to some extent by what is called the connecting link, seems, on a casual inspection of the drawing, to be less in this machine than in those where the forward attachment of the helical spring is a fixed point on the tongue. Whether this be so or not is, however, immaterial. But we note on the machine which has the “connecting link” and “equalizing lever” a rod from the inner shoe extending diagonally upward and forward to the whrfñetree attachment. This rod is pulled by its forward end to lift or ease from the ground the inner shoe as the horses draw the machine in mowing. Plainly, the helical spring is depended on to balance the outer shoe, and prevent its dragging in response to the continuous upward pull of the rod referred to on the inner shoe. Without dwelling on the matter, the better conclusion seems to be that the spring in appellee’s machine operates in the same way, and substantially to the same result, as the spring in the combination of the third claim of the patent in suit.
It is insisted that the combination of the third claim is anticipated by a machine called in the record “The Advance,” and made on the lines of a patent issued April 27, 1869, to McCormick, Erpelding, and Baker. Eig. 2, which accompanies the specification of that patent, is here shown:
*179
The parts to be looked at are the lever, H, pivoted to the frame of the machine immediately below, h2, the crooked link, g, pivoted at its forward end to the lower end of the lever, H, and the chain, g1, which passes from the rear end of link, g, over the rocking segment, Gr, and down to the longer arm of a lever, which is not lettered, but which corresponds to the lever, I, of the patent in suit. If the lever, H, were not held approximately upright by a catch of some sort on the frame, then, when the machine is in operation, said lever would drop forward to the tongue, its lower end being pulled on by the weight of the .chain and the rocking segment, Gr, which latter would drop down, swinging on its pivot, and be overbalanced by its own weight and that of the loosened chain. If the lever, H, were held upright by a fixed or rigid catch or notch, it would be continually rattling against its support by the varied impulses from the flnger-bar— through the lever, chain, and segment — as the machine is drawn over the ground. The use of the lever, H, is to- raise the .finger-bar, as occasion may require, entirely out of operative position. In order io keep the handle upright, and aví thin reach of the driver, and in order to keep the chain and segment in position, and to prevent rattling, a straight spring, h2, is fastened at one end by a bolt to lever IT. The other end extends downward, and is caught, when the machine is in operation, against a projection of some sort from the frame. As indicating the function of spring h2, the specification of the patent says: “A spring, li2, on the lever, serves to keep it in a position convenient to the hand. A link, g, and chain, h1 [this is-a mistake; the letter is g1], connects this lever with the finger-beam, first passing over the rocking segment, Gr.” It will he seen that the idea of taking from the finger-bar its two shoes, lever, and hinge-bar a portion of the combined weight, so as to float the finger-bar throughout its length more lightly over the ground, is not contained in this patent. The spring h2 is not located in the right place, and has not to any degree the function of the spring in the sheave of the patent in suit, or of the powerful helical spring of appellee’s machine;. *180and the result of the combination is not the result of the combination specified in claim 3.
In the model of the Advance machine put in evidence the hand-lever, when the machine is in operation, inclines decidedly forward. The spring h2 is curved in its upper part like the letter S. Its lower end, coming down nearly straight, bears against a ledge on the frame, thus preventing the lever from dropping further forward, and holding it against the slight pull on its lower end, needed to keep the chain and segment in position. It is not contended by appellee that this spring has the function of claim 3 in lifting and floating the finger-bar and its appendages. The insistence is, as already stated, that the helical spring of the machine complained of has substantially no other function than that of the spring in the Advance machine, or of the spring n2 in the patent of April 27, 1868. It may be here added that the little spring of the Advance and of the patent last named is not secured at one end to the frame of the machine as in claim 3, or as in the machine complained of. This spring merely affords an elastic support for the hand-lever, it is carried by the hand-lever, and its lower end bears or thumps intermittently against the ledge or bearing place on the frame as the machine is drawn over the ground in mowing.
A patent to one Heston under date of February 6, 1872, is much dwelt on as going to the matter of anticipation. This patent shows a lever hinged to a drooping corner, of the frame of a mowing machine, and with .its shorter arm bearing on the heel of a finger-bar, also hinged at said corner. The specification contains the following statements:
“The long arm of this lever projects inwardly, or. toward to rear of the machine, where its position may be controlled by any suitable device erected upon the machine for that purpose; or a weight may be attached to it, which shall counterbalance the outer-end of the cutter-bar, and thus such bar be kept in its position by changing the position of this arm of the lever, the opposite or short arm of which bears upon the inner end of the cutter-bar.”
Tbe patentee goes on to say, with reference to tbe working of bis device, that bis lever “will be operated so as to cause its inner end to assume a bigber or lower position with reference to tbe frame of tbe machine, which operation will cause tbe outer end of tbe finger-bar to be raised or.lowered, and thus tbe grass may be cut of an even length, whether tbe machine be used upon even or uneven ground.” . The function of lifting on tbe inner shoe, and so changing its weight or bearing on the ground to correspond with tbe lift on tbe outer end of tbe finger-bar, is not suggested in this patent. If a weight be attached to tbe extremity of the long arm of the lever, tbe effect would be to pull up tbe short arm, and so drop tbe outer end of tbe finger bar, with its full weight, on tbe ground. If tbe longer arm of tbe lever be curved upward and backward over tbe shorter arm till it droops across and forward of tbe finger-bar or cutter-bar, a weight attached to it might “counterbalance the outer end of tbe cutter-bar,” but the inner shoe, instead of being also eased from the ground, would be pressed down by tbe added weight so hung upon tbe forwardly bent and projecting long arm of tbe lever. *181Now, assuming that a weight "would be the same in action for the purpose of floating a finger-bar as a spring, and assuming a familiarity with the combination of the third claim of the patent in suit, or the like combination as used by appellee, one might well devise a coupling between the long arm of Heston’s lever and the frame of the machine which would serve as a prototype. But this would be to construct the anticipating device, rather than to find it in the prior art.
The decree below is affirmed.