stances as a criterion. But his meaning doubtless is that these are characteristic of an improvement constituting an invention which may serve to distinguish it where other characteristic distinctions are wanting; and Chancellor Kent would not probably be understood to lay down a different doctrine. The use of different elements of motion, or different mechanical principles or combinations offer equally marked grounds of discrimination, which are no less to be resorted to, than the method of operating and the result. Indeed the result or effect can scarcely be considered a criterion, for this by itself is not, as we have seen, patentable. In order to distinguish whether an alleged invention is patentable as such, and not merely a slight, immaterial, formal variety of what was already known, whether patented or not, we must look, not at a part merely, but at all of the characteristics of a patentable invention, the elements, principles, method or mode of operation, and according as we find these, originally, more or less combined in the alleged improvement, it will appear proportionably more or less satisfactorily to constitute the basis of a patent.

The following case in the Court of King's Bench, in England, illustrates what may be considered as amounting to a patentable improvement. A patent was granted for an improvement in the manufacturing of chain cables. The improvement was alleged to consist in so applying the link to the force to operate

on it, that that force should operate in one place, namely at the end; and this was effected by having a broad-ended bar across, instead of a conical one, which broad-ended bar lapped round the link, instead of perforating it; the former bars weakened the link, and they were weak in themselves, and if broken, there would be a pressure in some other part. The links were to have circular ends, and sides nearly parallel, but bulging out towards the middle. Abbott, C. J. "As at present advised, I am inclined to think that the combination of a link of this particular form, with the stay of the form used by the patentee, although the form of the link might have been known before, is so far new and beneficial as to sustain a patent." Bayley, J. was of the same opinion.70 In this case a link of the same form had been before in use, and it had been strengthened by a bar across it, but a change of the form of this bar, and the manner of attaching it to the link, was considered, and as it should seem with very good reason, by Chief Justice Abbott and Mr. Justice Bayley, to be a good foundation for a patent. The case went off, however, upon other grounds.

The provision of the act of Congress that the party making an improvement should not be entitled thereby to use the original machine, if it was subject to a

70 Brunton v. Hawkes, 4 B. and Ald. 540.

patent right, is introduced merely for the purpose of excluding any inference that the granting of a patent for an addition impaired the right of the original patentee. There would, however, have been very slight grounds for any such pretence, had the clause not been introduced, since the fact of granting a monopoly necessarily excludes others from the use of the article without the permission of the patentee during the existence of the exclusive privilege."

Sec. XII.-CHANGE OF FORM, PROPORTIONS, OR MATERIALS. INSUFFICIENCY OF THE INVENTION. ORNAMENTS.

The second section of the act of Congress of 1793, which authorizes a patent for an improvement, declares that simply changing the form or the proportions of any machine, or composition of matter, in any degree, shall not be deemed a discovery." This construction would undoubtedly have been put upon the law without any such express exception. It is indeed but the branch of a more general rule in giving a construction to the law, namely, that any change or modification of a machine or other patentable subject, which would be obvious to every person acquainted with the use of it, and which makes

71 See Fox, ex parte, 1 Ves. & B. 67.

no material alteration in the mode and principles of its operation, and by which no material addition is made, is not a ground for claiming a patent. To permit a formal, trivial change in an article to be patentable, or a reconstruction of it upon substantially the same principles, with unimportant differences in form or proportions, would defeat the beneficial operation of the statute and in effect repeal it. In considering the subject of the infringement of patents, we shall see more distinctly the construction put upon the statute in this respect, and it will appear that the courts carry out the motives and reasons of this exception in deciding what is an infringement, and what improvements are the subjects of a distinct patent.

The principle of this provision of the statute is as applicable to most alleged new inventions as to professed improvements or patented machines, since almost every invention is an alleged improvement, either on what has been patented, or what has been practised without ever having been subject to a patent, and as soon as a patented art or machine has become free by the expiration of the patent, it stands upon the same ground as any art or machine which has been in free public use time out of mind. To authorize a patent in either case, there must be, not merely a formal, trivial variation, but a distinguishable, substantial difference.

In a case in the English Court of Chancery, Mr.

Bell, one of the counsel, justly remarked that "it was not necessary to show that an invention was the result of long application or deep skill. He remembered that many years ago ladies wore flowered tabbies. The method of working the flowers was discovered by mere accident; a man having spit upon the floor, placed his hot iron on it, and observed that it spread out into a kind of flower. He afterwards tried the experiment upon linen, and found it produced the same effect. He then obtain

ed a patent, and lived to make a considerable for

The sufficiency of the invention depends not upon the labor, skill, study, or expense applied or bestow

ed able from what is familiar and well known, and also substantially and materially, not slightly and trivially SO. This requisite of an invention is sometimes expressed to be a difference in principle.

upon it, but upon its being diverse and distinguish

"What constitutes a difference in principle between two machines, is frequently a question of difficulty, more especially if the difference in principle is considerable, and the machinery complicated. But we think it may safely be laid down as a general rule, that where the machines are substantially the same, and operate in the same manner, to produce the same result, they must be in principle the same.

72 Walker v. Congreve, 29 Rep. of Arts, 2d Series, Vol. 29, p. 311.