arises either to the nature of the grant or the specification which has been enrolled by the plaintiff." If the patent is invalid there can be no infringement in the sense that a patent which has no legal existence cannot be infringed. But assuming that it has a legal existence, the question is for the jury. This explains the apparently contradictory decision in Curtis v. Platt (e), in the House of Lords. The question of infringement was there taken as involving the validity of the patent. It is equally an infringement whether the defendant acted in ignorance of the plaintiff's patent or not. In Heath v. Unwin (ƒ), Parke, B., delivering the judgment of the Court, said:"There was therefore no intention to imitate the patentee's invention, and we do not think the defendant can be considered to be guilty of any indirect infringement if he did not intend to imitate at all.” This judgment certainly gives an erroneous impression of the law, and Shadwell, V.-C., when the same case came before him (g), said:" The party complaining of the act is not the less prejudiced by it because it was committed unintentionally; and my opinion is that, if a party has done an act that is injurious to the rights of another (though without any intention of doing him an injury) he is answerable for the consequences. In Stevens v. Keating (h) the Lord Chancellor disapproved of the case in the Court of Exchequer; and I must decline to act upon the principle which it lays down." Subsequently, when Heath v. Unwin came before the House of Lords, the opinion of the judges being taken, Parke, B. (i), acknowledged the error into which the Court had fallen, and approved of Stevens v. Keating. In Stead v. Anderson (k), Wilde, C. J., tersely puts it :-"The question of infringement depends not on what the defendant intends, but on what he does." So it is immaterial whether the defendant was aware that the thing was patented or not, since in law every person in the realm (e) L. R., 1 H. L. 337; 35 L. J., Ch. 852. (f) 14 L. J., Ex. at p. 156. (g) 15 Sim. 553. (h) 2 Web. P. C. 176. (i) 25 L. J., C. P. at p. 19; 5 H. L. Cas. 505. (k) 2 Web. P. C. 156. is taken to have notice of a patent in the same way that he is taken to be aware of the law (1). And the converse is also sound-if a person intending to infringe a patent does not in fact do so, he will not be taken to have infringed (m). In M'Cormick v. Gray (n) the specification, after describing several parts of reaping machines, including some cutting blades of peculiar construction, claimed: "The construction of reaping machines according to the improvements before described—that is to say, the constructing and placing of holding fingers, cutting blades, and gathering reels, respectively, as before described, and the embodiment of those parts as so constructed and placed, all or any of them in machines for reaping purposes, whether such machines are constructed in other respects as before described, or however else the same may in other respects be constructed." The defendant made and sold cutting blades similar to those described by the plaintiff's patent, which were capable of being used in the plaintiff's reaping machine. Bramwell, B., in giving judgment, said:-"A man could not make the blade of a knife without infringing this person's patent, because you may intend to put it into a machine, or you may not. I think it is a very clear case, and I am satisfied there is no difference between making a thing with one intent and making it with another, because I always understood that if a man may do a thing, he may do it with whatever intent he pleases." It will be observed, that in this case, to make the knives was no infringement, and there was no evidence of the defendant having applied them to reaping machines (o). Thus we see that infringement, as taken apart from the question of validity, is a matter of fact, and that intention is not material to the conclusion (p). To prove infringement, it must be shown that there is a (1) Walton v. Lavater, 29 L. J., C. P. 275; Curtis v. Platt, 11 L. T., N. S. 245. (m) Newall v. Elliott, 10 Jur., N. S. 954. (n) 31 L. J., Ex. 42. (0) See, however, Bancroft v. Warden, Romilly's Notes of Cases, 103. (p) See also Yourg v. Rosenthal, 1 P. O. R. 29, 39. substantial resemblance (q). The infringement must be of a part for which the patent was granted, and not merely of a part described in the specification (r). The question as to what will or what will not amount to infringement, like many other points which arise in the law of letters patent, must depend upon the facts of each particular case, and the decision in one case cannot possibly bind the decision in another; consequently the consideration of decided cases is only useful as showing the principles which underlie the judgments in those cases. In Nobel's Explosives Co. v. Anderson, Romer, J., said (s): "Several cases were cited to show the canons of construction on which the Courts have acted in different cases relating to infringements. But it is not necessary for me to deal with these cases in detail, for I desire emphatically to state that, in my view, one principle only governs all the cases, whether they relate to so-called 'master' patents, or patents dealing with discoveries in matter of principle, or to any other kind of patent; and that principle is this: In order to make out infringement, it must be established, to the satisfaction of the Court, that the alleged infringer, dealing with what he is doing as a matter of substance, is taking the invention claimed by the patent; not the invention which the patentee might have claimed if he had been well advised or bolder, but that which he has in fact and substance claimed on a fair construction of the specification." In the same case, in the Court of Appeal, Kay, L.J., in his judgment, said (t): "I think the law now is reasonably well settled. There are two classes of cases; one where a patentee has invented a new method of producing a known result, the other where he has invented a new result, and has described one method of producing it. According to the dictum of Baron Alderson in Jupe v. Pratt (u), which, as has been pointed out in subsequent cases, was a dictum during the argument addressed to some argument of counsel which he was then considering, if a (q) Stead v. Anderson, 2 Web. P. C. 151. (r) Croll v. Edge, 19 L. J., C. P. at p. 264. (s) 11 P. O. R. 115, 127. patentee has invented a new result, and has described one method of obtaining that result, he may prevent anybody else from obtaining the same result by any other method. In my opinion that went much too far, and I need not refer to any authority which more clearly shows that than the subsequent judgment of Baron Alderson in Neilson v. Harford (x), where he pointed out that if that were the law the result of such a patent would be a patent of the principle itself, because when you had discovered a new result, if, by showing one method of producing that result, your patent covers every other method of producing that result, in point of fact you patent the principle which leads to that result; and that is perfectly good criticism upon the earlier dictum of Baron Alderson, which I cannot help thinking was only put arguendo, and is the proper limitation of the generality of that first dictum. Mr. Justice Pearson, in the Badische Anilin case (y), seems to have adopted the earlier dictum of Baron Alderson, without observing the limit put upon it by his subsequent judgment, and respectfully I differ from the statements of the law as stated by Mr. Justice Pearson in that case. The true result, I think, is stated very well by the late Lord Justice Cotton in the case of the Automatic Weighing Machine Co. v. Knight (z). He observes the dictum in Jupe v. Pratt, and he says:-Those were the expressions used by Baron Alderson during the discussion, probably to meet something that was said by counsel, and did not express his full opinion. You can prevent anyone from using the same method of carrying that principle into effect, and you can prevent anyone from using only the same thing, with a colourable difference. That is what we had to consider in Proctor v. Bennis (a). Where there is a principle first applied in a machine capable of carrying it into effect, the Court looks more narrowly at those who carry out the same principle, and say they do it by a different mode, and looks to see whether, in effect, although the mode is not exactly the same, it is only a colourable difference, a mechanical equivalent for a substantial part of the patentee's invention being looked upon as (a) 1 Web. P. C. 295, 355; 8 M. & W. 806, 820. (y) 2 P. O. R. 91. (z) 6 P. O. R. 297, 304. a mere colourable difference, and, therefore, he being entitled to an injunction against that mode of carrying out his principle, which is only the same in substance as that which he patented, though there are colourable differences.' I take the law as to be clearly settled thus, that if the result of the patent is entirely new, and one method of arriving at that result is described on the face of the patent, the patentee cannot say that enables me to treat every other method of arriving at that result as an infringement,' but the question is in every case whether the method which he says is an infringement is so like to the method which he has himself described as to be substantially the same, or, in other words, only colourably different." In Curtis v. Platt (b), Wood, V.-C., said :-" Where the thing is wholly novel and one which has never been achieved before, the machine itself which is invented necessarily contains a great amount of novelty in all its parts, and one looks very narrowly and very jealously upon any other machine for effecting the same object, to see whether or not they are merely colourable contrivances for evading that which has been before done. When the object itself is one which is not new, but the means only are new, one is not inclined to say that a person who invents a particular means of doing something that has been known to all the world long before has a right to extend very largely the interpretation of those means which he has adopted for carrying it into effect. Because otherwise that would be to say that the whole world is to be precluded from achieving some desirable and wellknown object which everybody has had in view for years. In such a case it may be said that the means taken are simply mechanical equivalents for the means previously adopted for arriving at the same object." The result of the decided cases clearly shows that a man will be held to have infringed if he has taken the pith and essence of the invention (c), and that when the invention is merely for an improved mode of attaining an old object the pith of his invention (b) L. R., 3 Ch. D. 136, n. (c) Clarke v. Adie, L. R., 2 App. Cas. 315, 320; Proctor v. Bennis, 4 P. O. R. 333, 345; Wenham Gas Co. v. Champion Gas Co., 9 P. O. R. 55, 56; Benno Jaffé v. Richardson, 11 P. O. R. 112. |