The distinction of a mere formal variation from a substantial improvement is in many cases very nice. In a case before Lord Ellenborough, Huddart had obtained a patent for a new mode of making cables and other cordage. It appeared that his invention differed from Belfour's, because that which was effected with a ring by Belfour, was produced by a tube in the mode of making ropes by Huddart. Lord Ellenborough "The tube does seem to me an important difference from the mere circle through which the strands pass, because it keeps them in a degree of confinement for a longer time, and more certainly obtains the end pointed out; in Mr. Belfour's specification the same end is to be attained; and had the patent been taken for that to be done by a tube, which was before done by a ring or circle, I should have thought the patent good; for that is a distinct substantive invention."

The substitution of one material for another is not, at least ordinarily, an invention for which a patent can be claimed. Sir John Leach, in an argument made by him as counsel, in the case of an alleged improvement in the construction of barrels for containing gunpowder, said, "The making of an old machine of new materials, could not be a discovery; and the plaintiff could claim no protection, for an invention, the only merit of which consisted in being

77 Huddart v. Grimshaw. Dav. Pat. Cas. 297.

made of brass instead of wood. When tea was first introduced into this country, earthen teapots were used; but could a person who made the first one of silver be entitled to a patent?"" This position is correct in general, and yet there may be cases in which the substitution of a different material may be a matter of contrivance and invention, and in such a case the particular mode of applying the new material would be a good subject of a patent.

The provision on the subject of change of proportions is expressly extended by the act of Congress, ot compositions of matter as well as to machines, and yet there are instances of compositions of matter in which the proportions are material. In one case one ground of holding the patent to be void, was, that the exact proportions in which lime and other ingredients were to be used in making iron, to prevent cold-short, were not stated.79 This was assuming the proportions to be material, and if so, then at change of proportion may be an essential improve

ment.

When the invention depends materially on the proportions of a mixture or composition of matter, and where, accordingly, a change in this respect makes a different process or a different result, such

78 Walker v. Converse. Rep. of Arts, 2d Series, Vol. 29, p. 311. Mr Godson cites this argument of Sir John Leach as an opinion given by him as Vice Chancellor.

79 Hill v. Thompson, 3 Meriv. 624.

a change would certainly come within the description of patentable subjects in the second section of the act of Congress; it would not be "simply" a change of proportions.

The French law of 1791 classes mere ornaments with changes in form and proportions, as not being subjects of patents. But this appears to be a very questionable position, for it would never be contended in case of an invention of which a part was ornamental merely, that this part might be infringed with impunity; and there appears to be no more ground for yielding any more protection to ornamental parts in an original invention, than in an improvement, or in a case where a part of the invention was ornamental, than one which should be wholly confined to ornament.

Sec. XIII.-LEGALITY.

An invention, to be patentable, must not only be new, but lawful. The sixth section of the English. statute of monopolies, permits the monopolies of new manufactures, “so they be not contrary to the law." The acts of Congress which constitute our patent law, contains no similar provision; nor was any such necessary in the act of Parliament, since it would be implied, though it were not expressed. The construction put upon the acts of Congress by the Amer

ican courts in this respect, is the same as that put upon the act of Parliament by the English courts.

A very ingenious instrument is said to have been invented by a London pickpocket to facilitate the practice of his art, of which he made the first experiment, and successfully, upon the artist by whom it was manufactured. There needs no express exception to prevent such an instrument from being patentable, since it would be quite absurd to encourage and reward by one law the art of violating another. So a chemical composition for poisoning people without danger of detection, would not be the subject of a monopoly under the patent law. This is in pursuance of a universal principle of jurisprudence. It is the principle of construction of the French patent law, which contains no express exception of unlawful industry. "It would," says M. Renouard," "be preposterous to guaranty to a man the exclusive right of doing what the law would punish when done."

Sec. XIV.-USEFULNESS.

By the sixth section of the English statute of monopolies it is provided that, in order to exempt a manufacture from the general prohibition of monopolies, it must be one that is "not mischievous to the

80 p. 167. c. 5. s. 12.

State by raising the price of commodities at home, or hurt of trade, or generally inconvenient." The only part of the act of Congress of 1793, in this respect, is simply the epithet useful, the provision of the first section being, that if any one shall allege that he has invented a useful art, machine, manufacture or composition of matter, he may apply for a patent. Mr. Godson says, in regard to the requisite usefulness, that "if the article that is produced by the machine be old, it must be furnished to the public at a much cheaper rate. The community must receive some benefit from the invention; and when it is not a new article which is introduced, the old one must, in some respect, be rendered a better commodity for trade.”’Ɛ1

In some of the earlier cases in Pennsylvania and Massachusetts for infringements of patents, the defendants, putting the same construction upon the act of Congress as that put upon the English statute of monopolies by Mr. Godson, and by some of the English judges, set up the defence that the machine, for the infringement of which the action was brought, was not a useful one, as it was no improvement on the methods previously in use for the same manufacture, and accordingly that it did not come within the description of inventions for which a patent was au

81 Treatise on Patents, p. 70, 71. See Manton v. Manton, Davis's Pat. Cas. 349; Lewis v. Davis, 3 Car. & P. 502. See also remarks of Abbott C. J. 2 B. & Adol. 349.