under strict legal scrutiny. In order that a patent should be held valid in a court of law :

1. The Invention must possess a certain amount of utility; must display some degree of novelty; and must have been attained by the exercise of some measure of ingenuity.

2. The Patentee must be the true and first inventor, that is, he must not have obtained the invention from another person (unless he has imported it from abroad); nor must he have derived it from a printed book; nor from a patent specification published in this country or introduced from abroad.

3. The Specification, that is the patentee's formal description of his invention, must be accurate, intelligible, and sufficient; it must point out distinctly what the patentee claims as his own; and must not claim anything that is not his own.

Besides treating of these subjects, the procedure in applications for patents will be explained in this volume. The Patent itself, its form, intent, and duration, and the dealings with it by way of Assignment and Licence, will be expounded. Various contentious matters, such as oppositions to grants, the infringement of patent rights, the revocation of patents, and the proceedings taken to restrain a patentee's threats will be dealt with. Certain collateral topics, such as the amendment of specifications, the registration of patents and of documents relating thereto, and the international and colonial arrangements for the reciprocal issue of patents, will be handled. A brief account of the Patent Office establishment, where the business of obtaining patents is transacted, will be given; and lastly, a short chapter on the Institute of Patent Agents will be found at the end of the treatise.

I

CHAPTER II.

THE SUBJECT-MATTER OR NATURE OF A PATENTABLE INVENTION-A BARE PRINCIPLE NOT PATENTABLE- PROCESSES -CHIEF CLASSES OF PATENTABLE INVENTIONS.

IN proceeding to consider the subject-matter or nature of the inventions which may be legally protected by patents, it is proper to premise that no general definition can be given which shall exactly mark out what can and what cannot be included in a valid patent. Where the invention is not one of a well-known class, it will be much better for the inventor to consult some one conversant with such matters -some one whose practical experience comes in aid of general principles, and who is bound by his profession and standing in society to the utmost secrecy-than to rely altogether upon what is stated in books, or upon a narrow range of precedent. It is the more important that the inventor's attention should be drawn to this point previous to his incurring expense, since a patent is taken out entirely at the risk of the inventor, the Crown in no degree guaranteeing the validity of its grant, which, if contested, will be judged by the abstract rules of law applicable to the case.

As we have already remarked, it is not every kind of discovery which can be protected by a patent. No invention is patentable which does not fall within the language of the Act of King James, and is not referable to some 'manner of new manufactures.' It is true, as we shall see further on, that these words have received a very wide interpretation; still they have never been held to include such inventions and discoveries as that of an abstract principle without reference to any of its practical applications; or that of a game of skill or chance irrespective of the

appliances for playing it; or that of a method of calculation unconnected with apparatus for working it; or that of a vegetable suitable for food; or that of a natural substance applicable to a useful purpose, such as guano or mineral phosphate of lime; or that of an elementary body such as a metal. Patents which relate to inventions and discoveries such as these can only be maintained when they are taken out for the manufacture of the apparatus required for the given purpose, or for methods of preparing the natural substance for some useful end.

Before giving examples of the chief classes into which those inventions which have received the sanction of judicial decision are divisible, it may be well first to clear the ground a little by making some remarks on the cases relating to Principles and Processes.

It has been repeatedly laid down by the Courts that

BARE PRINCIPLES ARE NOT PATENTABLE.

A principle may be of the utmost value in the eyes of philosophers; its discovery may lead to highly important consequences, and form the germ of a striking advance in civilisation; yet unless its discoverer can show at least one application of it to a useful purpose-unless he can point out the means of gaining therefrom some immediate material advantage-he is not permitted to exclude his fellow-subjects from turning it to any account they like. 'I rather think it would be difficult' (said Lord Kenyon, in Hornblower v. Boulton, 8 T. R. 95; Dav. Pat. Ca. 221) to form a specification of a philosophical principle; it would be something like an idea without a substratum.'

Neither are principles in a more restricted sense patentable, unless they are embodied in a concrete form and their application to some purpose of utility indicated. You cannot' (said Alderson, B., in Jupe v. Pratt, 1 W. P. C. 145) 'take out a patent for a principle. You may take out a patent for a principle coupled with the mode of carrying the principle into effect, provided you have not only discovered the principle, but invented some mode of carrying

it into effect. But then you must start with having invented some mode of carrying the principle into effect.' 'Undoubtedly' (said Eyre, C. J., in Boulton v. Bull, 2 H. Bl. 463) there can be no patent for a mere principle; but for a principle so far embodied and connected with corporeal substances as to be in a condition to act and to produce effects in any art, trade, mystery, or manual occupation, I think there may be a patent. . . . It is not ' (referring to the case before him) that the patentee has conceived an abstract notion that the consumption of steam in fire-engines may be lessened, but he has discovered a practical manner of doing it, and for that practical manner of doing it he has taken his patent. Surely this is a very different thing from taking a patent for a principle; it is not for a principle, but for a process. Again, the substance of the invention is a discovery that the condensing the steam out of the cylinder, and protecting the cylinder from the external air, and keeping it hot to the degree of steam-heat, will lessen the consumption of steam. This is no abstract principle; it is in its very statement clothed with practical application.'

In the much-debated case of Neilson v. Harford (1 W. P. C. 295) a great deal was said as to the point now before us. Neilson took out his patent in 1828 for the improved application of air to produce heat in furnaces, and in his specification declared that his invention consisted in passing a blast of air from the blowing-apparatus into an air-vessel kept heated to a red-heat, or nearly so, and from that vessel, by means of a pipe, into the furnace; that the size of the vessel must depend on the blast, and on the heat necessary to be produced, but that the form of the vessel was immaterial to the effect, and might be adapted to the local circumstances or situation. The defendants, who were alleged to have infringed this patent, contended that it was void, as being for a principle. The Court of Exchequer, after full consideration, thought that the plaintiff did not merely claim a principle, but a machine embodying a principle. The case must be considered as if the principle being well

known, the plaintiff had first invented a mode of applying it by a mechanical apparatus to furnaces; and the inven tion then consisted in this-the application of air heated up to red-heat, or nearly so, and the interposition of a receptacle for heating air between the blowing-apparatus and the furnace. And Mr. Baron Alderson, in reply to the argument of the plaintiff's counsel that he claimed every vessel and every shape of closed vessel in which air could be heated between the blowing-apparatus and the furnace, said, Then I think that is a principle, if you claim every shape. If you claim a specific shape, and go to the jury and say that which the other people have adopted is a colourable imitation, then I can understand it. If you claim every shape, you claim a principle. There is no difference between a principle to be carried into effect in any way you will, and claiming the principle itself. You must detail some specific mode of doing it.' (See L. J. Lindley's approving remarks on this dictum. Automatic Weighing Machine Co. v. Knight, 6 R. P. C. 308.)

In the same case (1 W. P. C. 342) Alderson, B., said, ‘I take it that the distinction between a patent for a principle and a patent which can be supported is, that you must have an embodiment of the principle in some practical mode, described in the specification, of carrying the principle into actual effect; and then you take out your patent, not for the principle, but for the mode of carrying the principle into effect. In Watt's patent, which comes the nearest to the present of any you can suggest, the real invention of Watt was, that he discovered that by condensing steam in a separate vessel, a great saving of fuel would be effected by keeping the steam-cylinder as hot as possible, and applying the cooling process to the separate vessel, and keeping it as cool as possible; whereas before, the steam was condensed in the same vessel; but then Mr. Watt carried that practically into effect by describing a mode which would effect the object.'

The words of Lord Justice Clerk Hope, in the case of the Househill Company v. Neilson (1 W. P. C. 683), may be cited in reference to the same point. A patent cannot be