Leaving the discussion of general considerations, we will now give an outline of the law affecting patent privileges in the United Kingdom. Formerly the reigning prince considered himself entitled, as part of his prerogative, to grant privileges of the nature of monopolies to any one who had gained his favour. These grants became so numerous that they were oppressive and unjust to various classes of the commonwealth; and hence, in the reign of James I., a statute was wrung from that king which declared all monopolies that were grievous and inconvenient to the subjects of the realm to be void. (See Monopoly.) There was, however, a special exception from this enactment of all letters patent and grants of privilege of the “sole working or making of any manner of new manufacture within the realm to the true and first inventor of such manufacture, which others at the time of making such letters patent and grants should not use, so they be not contrary to law, nor mischievous to the state by raising of the prices of commodities at home or hurt of trade or generally inconvenient.” Upon these words hangs the whole law of letters patent for inventions. Many statutes were afterwards passed, but these were all repealed by the Patent Act of 1883 (46 and 47 Vict. c. 57), which, besides introducing a new procedure, modified the law in several particulars. When the law remains unaltered, it has to be gathered from the numerous decisions of the courts, for patent law is for the most part “judge-made law.” Of the law as it now stands we proceed to give an outline.

The inventions for which patents are obtained are chiefly either vendible articles formed by chemical or mechanical operations, such as cloth, alloys, vulcanized india-rubber, &c., or machinery and apparatus, or processes. It may be remarked here that a scientific principle cannot form the subject of a valid patent unless its application to a practical and useful end and object is shown. An abstract notion, a philosophical idea, may be extremely valuable in the realm of science, but before it is allowed to form a sound basis for a patent the world must be shown how to apply it so as to gain therefrom some immediate material advantage. With regard to processes, the language of the statute of James has been strained to bring them within the words “any manner of new manufacture,” and judges on the bench have admitted that the exposition of the Act has gone much beyond the letter. However, it is undoubted law that a process is patentable; and patents are accordingly obtained for processes every day.

The principal classes of patentable inventions seem to be these:—(1) new contrivances applied to new ends, (2) new contrivances applied to old ends, (3) new combinations of old parts, whether relating to material objects or processes, (4) new methods of applying a we!1-known object.

With regard to a patent for the new application of a well-known object it may be remarked that there must be some display of ingenuity in making the application, otherwise the patent will be invalid on the ground that the subject-matter is destitute of novelty. For example, a machine already in use as an excavator on land cannot be separately patented as an excavator under water; nor can a machine employed in the finishing of cotton goods be afterwards patented without alteration as applied to the finishing of woollen fabrics. A small amount of invention is indeed sufficient to support a patent where the utility to be derived from the result is great. A small step in advance, a slight deviation from known processes, may have been apparently brought about by the exercise of little ingenuity; but, if the improvement be manifest, either as saving time or labour, a patent in respect of it will stand. The mere omission of a step from some commonly practised process has been held sufficient to support a patent for a new method of manufacture; and how often do we see what appears to be a very trifling degree of novelty attended with very advantageous consequences, sometimes resulting in the entire revolution of a manufacture, or in a lowering of price appreciable in every pound of an article extensively used by the public?

Whatever be the nature of the invention, it must possess the incidents of utility and novelty, else any patent obtained in respect of it will be invalid. The degree of utility need not, however, be great. As to novelty, this is the rock upon which most patents split; for, if it can be shown that other persons have used or published the invention before the date of the patent, it will fall to the ground, although the patentee was an independent inventor deriving his ideas from no one else. The difficulty of steering clear of this rock will be apparent at once. Suppose A in London patents an invention the result of his own ingenuity and patient study, and it afterwards appears that B, in some distant part of the kingdom, had been previously openly using the same thing in his workshop, A’s patent is good for nothing. Thus, in one of the cases which arose out of Heath’s carburet of manganese patent —a patent celebrated in the law-courts—it appeared that three firms had used a process in the manufacture of steel which was substantially the same as that forming the subject of the patent. They had used the process openly in the way of their trade previous to the date of the patent, although it had not become generally known. This prior use of the invention was held to deprive the patent of validity. It is therefore a very frequent subject of inquiry, whether an invention has been previously used to such an extent as to have been publicly used in the sense attached by the courts to this phrase. The inventor himself is not allowed to use his invention, either in public or secretly, with a view to profit, before the date of the patent. Thus, if he manufactures an article by some new process, keeping the process an entire secret, but selling the produce, he cannot afterwards obtain a patent in respect of it. If he were allowed to do this he might in many cases easily obtain a monopoly in his invention for a much longer period than that allowed by law. The rule that an inventor’s use of the invention invalidates a subsequent patent does not, however, apply to cases where the use was only by way of experiment with a view to improve or test the invention. And it has been repeatedly decided that the previous experiments of other persons, if incomplete or abandoned before the realization of the discovery, will not have the effect of vitiating a patent. Even the prior discovery of an invention will not prevent another independent discoverer from obtaining a valid patent if the earlier inventor kept the secret to himself, the law holding that he is the “true and first inventor” who first obtains a patent.

When an invention is the joint production of more persons than one, they must all apply for and obtain a joint patent, for a patent is rendered invalid on showing that a material part of the invention was due to some one not named therein. The mere suggestion of a workman employed by an inventor to carry out his ideas will not, however, require that he should be joined, provided that the former adds nothing substantial to the invention, but merely works out in detail the principle discovered by his employer. In certain cases in which patents taken out by the celebrated Sir Richard Arkwright came to be inquired into, it was proved that the inventions were really made by persons in Arkwright’s employment. Their value being perceived by him, he adopted them, and obtained the patents in question, but under these circumstances they were adjudged invalid.

If it can be shown that the invention in respect of which a patent has been obtained was previously described in a printed book in circulation in Great Britain, whether such book be in the English or a foreign language, the patent is also invalid, because a man has no right to obtain a monopoly in that which is already a part of the stock of public information; and it is not necessary to prove that the patentee was acquainted with the book, and derived his ideas from that source. The most usual prior publication fatal to a patent is a prior specification of a similar invention. But persons are allowed to obtain patents for inventions imported from abroad, if such inventions are new within the realm, and if they acknowledge, on the face of their applications, that the inventions are imported, not original. Such patents are now common.

The attributes of novelty and utility being possessed in due degree by an invention, the chief remaining difficulty with which a patent has to contend resides in the complete specification, the instrument by which the inventor describes the nature of the invention and the means by which it may be carried into effect. An inventor is bound, in return for the monopoly conceded to him, to instruct the public how to work the invention when the monopoly shall have expired, and to inform them in the meantime what it is they are shut out from using; and now the patent is not granted till the complete specification is filed. The patentee is bound to make by this instrument a full disclosure of his secret; he must not keep anything back either wilfully or accidentally; he must render everything plain and clear, showing no attempt to mislead, and leaving nothing ambiguous; he must distinguish what is old from what is new; he must point out distinctly what it is that he claims as his own exclusive property, and he must take care that he claims no more than he is entitled to. Very many patents have been invalidated by a disregard of the requirements of the law, the most common fault being that the specification claims too much; in other words, it claims something that is already public property, or another man’s patented invention. And here we are brought back to the question of novelty. If a patentee discovers that his specification claims more than he is entitled to, he may put the matter right by filing an amendment, and excising the superfluous parts; but he will not be allowed to extend his daims in any degree. He may cut out anything, but he can insert nothing, except matter which is of the nature of correction or exp!anation.

The term for which a patent is originally granted is fourteen years, but the crown has been empowered by parliament and through the intervention of the judicial committee of the privy council, before which the proceedings take place, to extend the time of a patent from its expiration for any additional time not longer than fourteen years. But an extension will only be granted on the patentee showing that the invention is meritorious, and that he has not been adequately rewarded in spite of his best efforts directed to that end. What is adequate reward depends on the special circumstances of each case. The crown has hitherto had a right to the free use of a patented invention, but this right has been abolished by the new Act.

Patent privileges, like most other rights, can be made the subject of sale. Partial interests can also be carved out of them by means of licences, instruments which empower other persons to exercise the invention, either universally and for the full time of the patent (when they are tantamount to an assignment of the patentee’s entire rights), or for a limited time, or within a limited district. By an exclusive licence is meant one that restrains the patentee from granting other licences to any one else. By means of a licence a patentee may derive benefit from his patent without entering into trade and without running the risks of a partnership.

One of the regulations of the recent Act is that a patentee can be compelled by the Board of Trade to grant licences to persons who are able to show that the patent is not being worked in the United Kingdom, or that the reasonable requirements of the public with respect to the invention cannot be supplied, or that any person is prevented from working or using to the best advantage an invention of "which he is possessed.

A patentee’s remedy for an infringement of his rights is by civil suit, there being no criminal proceedings in such a case. In prosecuting such suit he subjects those rights to a searching examination, for the alleged infringer is at liberty to show that the invention is not new, that the patentee is not the true and first inventor, &c., as well as to prove that the alleged infringement is not really an infringement. But it may here be remarked that a patentee is not bound down (unless he chooses so to be) to the precise mode of carrying the invention into effect described in the specification. If the principle is new, it is not to be expected that he can describe every mode of working it; he will sufficiently secure the principle by giving some illustrations of it; and no person will be permitted to adopt some mode of carrying the same principle into effect on the ground that such mode has not been described by the patentee. On the other hand, when the principle is not new, a patentee can only secure the particular method which he has invented, and other persons may safely use other methods of effecting the same object. Instances of this occur every day; and it is well known that scores of patents have been taken out for screw-propellers, steam-hammers, water-meters, &c., each of which is limited to the particular construction described, and cannot be extended further. Again, where the invention patented consists of a combination of parts, some old and some new, the whole constituting a new machine or a new process, it is not open to the world to copy the new part and reject the rest. A man is not permitted to allege that the patent is for a combination, and that, the identical combination not having been used, there has been no infringement. If he has borrowed the substance of the invention, it will be held that he has infringed the patent.

A patent may be revoked by a court of law on any one taking proceedings for that purpose, and showing good ground for a revocation, such as want of novelty or utility in the invention, the fact of the patentee not being the inventor, insufficiency of the specification, fraud, or the like.

Patents are not now extended to the colonies, and such of the English colonies as possess a legislature are gradually acquiring patent laws for themselves (see infra).

The new Act enables the crown to make arrangements with foreign states for the mutual protection of inventions, under which a person who has applied for protection for any invention in a foreign state will be entitled to apply for a patent in England within a limited time in priority to other applicants (see p. 358).

The patent business of the United Kingdom is transacted at the Patent Office in London under the superintendence of the comptroller, an officer appointed by the Board of Trade, under whose direction he performs his duties. At this office is kept a register of all patents issued, of assignments of patents, licences granted under them, &c. An illustrated journal of patent inventions is published at the same office, where printed copies of all specifications can also be obtained. The proceedings taken with a view to obtain a patent commence with an application drawn up in a special form and accompanied by a description of the invention and a declaration as to its originality. Any person, whether a British subject or not, may apply for a patent. The actual inventor must always be a party to the application, but he may join other persons with himself, and the patent when issued will be granted to them all jointly. The fees payable to Government on patents have been considerably reduced by the new Act, and they may now be paid by convenient annual instalments.

During the ten years ending with 1882 the average annual number of patents issued was 3506. There has been a large increase under the new law, the number of patents applied for in the first three months of 1884 being 5748.

Patents are frequently obtained through the intervention of persons termed patent agents, who devote themselves to this branch of business.

United States.— Lender an Act passed in 1874 a patent must in all cases be applied for in the name of the original inventor, although he may contemporaneously execute an assignment of the invention, and the patent will thereupon be issued to the assignee. Every application is referred to an official examiner. The patent will be refused if any part of the invention is wanting in novelty, or if the application is not in proper form. The applicant may, however, make a re-application, and if the inventor is dissatisfied with the report of the examiner he can appeal. Patents are...