The patent gives to the patentee the exclusive use of the thing patented, for seventeen years. If any other person, within that period, makes an adverse use of it, (and any use of it without the patentee's consent is adverse,) this is an infringement of the patentee's exclusive right, for which he has an adequate remedy. (p)

The question, What is an infringement of a patent right? is the great question of patent law; and often one of great difficulty, for many reasons. It is not easy to separate what is matter of law in the question from what is matter of fact. To decide the question of fact aright, often requires a thorough acquaintance with the laws of mechanics, and with various branches of natural

(oq) Gold-Separating Co. v. U. S. Dis-integrating Ore Co. 6 Blatchf. 307.

(p) It is said, however, that the making of a machine merely for philosophical experiment, or for the purpose of ascertaining its sufficiency to produce its described effects, is not an infringement. Whittemore v. Cutter, 1 Gall. 432; Poppenhausen v. Falke, 2 Fish. 181; Jones v. Pearce, Webst. Pat Cas. 125. - But see Watson v. Bladen, 4 Wash. 683. With these exceptions the question of infringement is one irrespective of motive. Parker v. Hulme, 1 Fish. 54.

ll science. And judges and experts, to say nothing of juries, often encounter questions in patent cases, both sides of which are so strongly supported, that either seems impregnable, were it not that the other is as much so. What better instance of this can be given, than a case in England, involving very large pecuniary interests, and turning entirely upon the question of infringement, wherein an eminent judge trying the case at Nisi Prius, ll held *that there was no infringement; then, of six judges in the Exchequer Chamber, four held that there was an infringement; then, when the House of Lords asked the judges of England for their opinion, seven held that there was an infringement, and four that there was not; and finally the House of Lords decided that there was no infringement? (q)

We shall endeavor to give some general rules, or principles, which may be of use to those who have to consider this difficult question; placing in our notes the cases which illustrate or which qualify these rules or principles.

There must be, to constitute an infringement, a copy of the patented article; and it must agree with that article in principle and in action and effect. (r) No device of language, and no avoid(q) Unwin v. Heath. 13 M. & W. 583; 12 C. B. 622; 6 H. L. C. 505. The patent was for the use of carburet of manganese in the manufacture of steel. Defendant made use of oxide of manganese and coal-tar, the materials of which the carburet of manganese is made; and it was contended that in this process these ingredients became converted into the carburet before the iron was changed to steel, but the scientific evidence on this point was very conflicting. The final decision of the House of Lords rested on the ground, that at the date of the patent the ingredients of the carburet of manganese were not known to be an equivalent for the carburet itself.

(r) Winans v. Denmead, 15 How. 830; Odiorne v. Winkley, 2 Gall. 53; How v. Abbott, 2 Story, 190; Parker v. Haworth, 4 McLean, 370; Brooks v. Bicknell, 3 McLean, 250; Rich v. Lippincott, 1 Fish. 1. But in order to constitute an infringement, it is not necessary that the device complained of should imitate the patented machine in every respect, or even that it should resemble it in form or external appearance, provided it be substantially the same in principle and mode of operation. Smith v. Higgins, 1 Fish. 537; Judson v. Cope, id. 615; Union Sugar-Refinery v. Mathieson,2 Fish. 600;

Cahoon v. Ring, 1 Clif. 582; Blanchard v. Beers, 2 Blatchf. 415; Barrett v. Hall, 1 Mass. 447; Wyeth v. Stone, 1 Story, 278; Dixon v. Moyer, 4 Wash. 68; Root v. Ball, 4 McLean, 177. But if by the change of form or proportion a new effect is produced, there is no infringement, as the change is not merely of form, but of principle also. Winans v. Denmead, 15 How. 380; Many v. Jagger, 1 Blatchf. 386; Davis v. Palmer, 2 Brock. 310; Aiken v. Dolan, 8 Fish. 187. And where several distinct improvements are claimed in one patent, the use of one of them alone will constitute an infringement. Moody v. Fiske, 2 Mass. 112; Emerson v. Hogg, 2 Blatchf. 1. Nor can the defendant embody in his machine the patented inventions of the plaintiff, nor entitle himself to use them, by adding improvements, or new inventions of his own or of others, thereto. Carr v. Rice, 1 Fish. 198; Colt v. Mass. Arms Co. id. 108; Howe v. Morton, id. 586; McCormick v. Talcott, 20 How. 405; Foster v. Moore, 1 Curt. 279; Woodworth v. Rogers, 3 Wood. & M. 155. To constitute an infringement of a combination, all the elements of the combination must be employed, or at least substantial equivalents for them. If one or more be omitted there is no infringement.

mm ance of what may seem to be a direct * contradiction to mm the description and claim of the patent, will necessarily prevent the interference complained of from being an infringement. The statute requires that the patentee shall give in his specification a description of his invention "in full, clear, concise and exact terms"; and it is plain that this means that the patentee shall be limited by his own specification; for his description cannot comply with this requirement, if he may go beyond it to find something which the defendant infringes. (s) And it is equally plain, that nothing must be judged an infringement which is not clearly so; for the public have an undoubted right to the whole ground not certainly occupied by the specification, for any ambiguity or omission by the patentee is his own fault, and he must bear the consequences. It would be very difficult to call that an * in nn

Prouty v. Ruggles, 16 Pet. 336; Stimpson 9. B. & S. R. R. Co. 10 How. 329; Eames v. Godfrey, 1 Wall. 78; Seymour v. Osborne, 11 Wall. 516; Dodge v. Card, 2 Fish. 116; McCormick v. Manny, 6 McLean, 539. And where an element is omitted in the defendant's device, the plaintiff will not be permitted to show that such element is useless. Vance v. Campbell, 1 Black, 427.