§ 307. An infringement involves substantial identity, whether that identity is described by the terms, "same principle," "same modus operandi," or any other. It is a copy of the thing described in the specification of the patentee, either without variation, or with only such variations as are consistent with its being in substance the same thing.1 What will amount to such a substantial identity cannot be stated in general terms; we can only look to individual cases for illustrations and applications of the general doctrine.

Thus, in Aiken v. Bemis,2 Woodbury, J., uses the following language: "The present was a case of the former character, for a combination, and the difference in the patent from the instrument here consists in this, that the hammer of the saw-set was all made of steel by Bemis, and that all but the point was made of wrought-iron in the patent. This looks, at first blush, as not a very material difference, and one rather colorable or accidental than designed. But when we advert to the evidence in the case, it appears that the use of wrought-iron was found by experiment to be much better than steel, and was hence patented, and this without making the specification in terms broad enough to cover steel also. It is a matter of doubt, therefore, whether the use of an inferior material for the hammer of the saw-set, when the patent covers only a superior one, is a legal violation of it. Why should the plaintiff complain of what he had tried, but deemed too useless that a machine, which raised water by a lever, was the same in principle with a machine which raised it by a screw, a pulley, or a wedge, whatever, in other respects, might be the similarity of the apparatus." See note on the "Principle of an Invention," at the end of this chapter.

1 In Walton v. Potter, Webs. Pat. Cas. 586, Sir N. C. Tindal, Ch. J., said: "Where a party has obtained a patent for a new invention or a discovery he has made by his own ingenuity, it is not in the power of any other person, simply by varying in form or in immaterial circumstances, the nature or subject-matter of that discovery, to obtain either a patent for it himself, or to use it without the leave of the patentee, because that would be in effect and in substance an invasion of the right; and, therefore, what you have to look at upon the present occasion, is not simply whether in form or in circumstances, that may be more or less immaterial, that which has been done by the defendants varies from the specification of the plaintiff's patent, but to see whether, in reality, in substance, and in effect, the defendants have availed themselves of the plaintiff's invention in order to make that fabric, or to make that article which they have sold in the way of their trade; whether, in order to make that, they have availed themselves of the invention of the plaintiff."

2 3 Woodb. & Minot, 348.

or valueless to be adopted? Had the patent extended only to the form or parts of the saw-set, combined as set out and made of any kind of materials, or saying nothing of the materials, the right would be violated by a machine of like form, as the form would be the sole matter patented. But when the patentee chooses to go further, and cover, with his patent, the material of which a part of his machine is composed, he entirely endangers his right to prosecute when a different and inferior material is employed, especially one which he himself, after repeated experiments, had rejected."

§308. If the invention of the patentee be a machine, it will be infringed by a machine which incorporates in its structure and operation the substance of the invention; that is, by an arrangement of mechanism which performs the same service or produces the same effect in the same way, or substantially the same way. But perhaps the only method of satisfactorily explaining what is meant by operating in the same or substantially the same way, is to cite from the instructions of the courts on this question in several of the leading patent cases. Thus, in Wyeth v. Stone,1 Mr. Justice Story charged as follows: "It (the defendant's machine) is substantially, in its mode of operation, the same as Wyeth's machine; and it copies his entire cutter; the only important difference seems to be that Wyeth's machine has a double series of cutters on parallel planes, and the machine of the defendant's has a single series of chisels in one plane. Both machines have a succession of chisels, each of which is progressively below the other, with a proper guide placed at such a distance as the party may choose, to regulate the movement; and in this succession of chisels, one below the other, on one plate or frame, consists the substance of Wyeth's invention. The guide in Wyeth's machine is the duplicate of his chisel plate or frame; the guide in the defendant's machine is simply a smooth iron on a level with the cutting-chisel frame or plate. Each performs the same service substantially in the same way." In Odiorne v. Winkley,2 the same learned judge said: "It is often a point of intrinsic difficulty to decide whether one machine operates upon the same principles as another. In the present improved state of mechanics, the same elements of motion and the same powers must be 1 Wyeth v. Stone, 1 Story's R. 273.

employed in almost all machines. The lever, the wheel, and the screw are powers well known; and if no person could be entitled to a patent who used them in his machine, it would be in vain to seek for a patent. The material question, therefore, is not whether the same elements of motion or the same component parts are used, but whether the given effect is produced substantially by the same mode of operation and the same combination of powers in both machines. Mere colorable differences or slight improvements cannot shake the right of the original inventor. To illustrate these positions, suppose a watch was first invented by a person so as to mark the hours only, and a second person added the work to mark the minutes, and a third the seconds; each of them using the same combinations and mode of operation to mark the hours as the first. In such a case the inventor of the second-hand could not have entitled himself to a patent embracing the inventions of the other parties. Each inventor would undoubtedly be entitled to his own invention and no more. In the machines before the court, there are three great stages in the operation, each producing a given and distinct effect: (1.) The cutting of the nail for the head; (2.) The griping of the nail; (3.) The heading of the nail. If one person had invented the cutting, a second the griping, and a third the heading, it is clear that neither could entitle himself to a patent for the whole of a machine which embraced the inventions of the other two, and by the same mode of operation produced the same effect; and if he did, his patent would be void. Some machines are too simple to be thus separately considered; others, again, are so complex, as to be invented by a succession of improvements, each added to the other. And on the whole, in the present case, the question for the jury is, whether, taking Reed's machine and Perkins's machine together, and considering them in their various combinations, they are machines constructed substantially upon the same principles and upon the same mode of operation."

One machine is the same in substance as another, if the principle be the same in effect, though the form of the machine be different. Thus in Boville v. Moore,1 Gibbs, C. J., said: "I remember that was the expedient used by a man in Cornwall, who endeavored to pirate the steam-engine. He produced an engine which, on the first view of it, had not the least resemblance to Boulton and Watt's engine; where you looked for the head you found the feet,

1 Boville v. Moore, Dav. Pat. Cas. 361, 405.

and where you looked for the feet you found the head; but it turned out that he had taken the principle of Boulton and Watt's; it acted as well one way as the other; but if you set it upright, it was exactly Boulton and Watt's engine. So here I make the same observation, because I observe it is stated that one acts upwards and the other downwards; one commences from the bottom and produces the lace by an upward operation, the other acts from above and produces it by an operation downwards; but that, if the principle be the same, must be considered as the same in point of invention." 1

In McCormick v. Seymour,2 Nelson, J., gave the following instructions: "The next objection taken by the defendants is that, assuming the divider of the plaintiff to be new and useful and patentable, and that he is entitled to the enjoyment of it free from any interference, still he is not entitled to recover, because the defendants have not used his separator, but a different contrivance. In order to take the separator of the defendants out of the charge of infringement, it is necessary that they should satisfy you that it is substantially and materially different from the plaintiff's; in other words, that it involves some new idea in its construction not to be found in the plaintiff's. If it is found there, of course it is an appropriation of his invention. If not, then it is an independent improvement and no violation of the plaintiff's right. It is proper to observe, in respect to this particular question, that whether the separator of the defendants be or be not an interference with that of the patentee, will depend upon, this, whether the plan which the defendants have employed, in constructing their separator and dividing the grain, is or is not in substance the same as the plain-. tiff's, and whether or not the differences that have been introduced by the defendants in their form of construction and in accomplishing the design which all these separators seek to accomplish, are merely differences in things not material or important; in other words, whether their plan is, in substance and effect, a colorable evasion of the plaintiff's contrivance, or whether it is new, and substantially a different thing. If the defendants have taken the same general plan and applied it for the same purpose, although they may have varied the mode of construction, it will still be, substantially and in the eye of the patent law, the same thing. Otherwise it will not."

1 Compare Buck v. Hermance, 2 Blatchf. 398. ' McCormick v. Seymour, 2 Blatchf. 240.

To the same effect, in Blanchard v. Beers,1 the same judge said: "It is material, at this stage of the case, to recall your attention to a principle already stated, namely, that whether or not the one machine is an infringement of the other, does not necessarily depend upon whether their mechanical structures are different. But the question is, whether (whatever may be the mechanical construction) the later machine contains the means or combination found in the previous machine, whether, taking the structure as you find it, you see the new idea embodied in it. If the combination of Blanchard is found substantially incorporated in the defendant's machine, then its mechanical construction, whatever it may be, is, as matter of law, but an equivalent for the mechanical construction of Blanchard's machine. No man can appropriate the benefit of the new ideas which another has originated and put into practical use, because he may have been enabled by superior mechanical skill to embody them in a form different in appearance or different in reality. For although he may not have preserved the exterior appearance of the previous machine, he may have appropriated the ideas which gave to it all its value. . . . It is unfair, when the question is between Blanchard's machine thus organized and a machine organized for one particular purpose and to produce one particular result of Blanchard's machine, such as the wagon-spoke, to hold that, because the machine organized for that specific purpose is differently constructed and dissimilar in appearance, and can produce the particular thing more rapidly, it therefore necessarily fails to embody the same idea or combination. We know that any machine constructed to accomplish a particular object or purpose may be often materially changed from the original construction, and yet do the work very well. There are mechanical equivalents, by the use of which the whole features may be changed, and a great departure made from the apparent principle and combination of the machine, and yet it may operate well. In view of this consideration, it should be particularly noticed, in this case, that the defendant's machine has been constructed for one object, for the purpose of turning wagon-spokes of slight irregularity of form, and therefore, as is obvious, may admit of very material changes from the original machine. It

1 Blanchard v. Beers, 2 Blatchf. 418. Compare McCormick v. Talcott, 20 How. 402; Winans v. Denmead, 15 How. 332; Sickels v. Borden, 3 Blatchf. 535; Dobbs v. Penn, 3 Well. Hurls. & Gord. 427.