Patent or Letters Patent, is a writ or grant in the king's name, and under the great seal, designed to secure to the proprietor of any new invention the monopoly of its advantages for the term of fourteen years; but this term is sometimes extended, under extraordinary circumstances, by act of Parliament, to a longer period. The term patent is also applied to the right conveyed, as well as to the instrument conveying it. Monopolies, unless granted for a limited period, and with the view to the ultimate benefit of the public. During the reign of Elizabeth, many unmerited monopolies had been granted, which had so prejudicial an effect upon the commerce of the country, that, towards the end of that monarch's reign, the clamour was so loud and general as to induce her to send a message to Parliament, announcing her intention to immediately cancel the most oppressive of the exclusive privileges she had granted. But however just maybe the feelings of opposition to monopolies in general, it will be readily allowed, that a patent for a new invention, for a few years, is only a just and reasonable compensation to the inventor, who is thus enabled to mature his discovery, and give it to the public, at the termination of his monopoly, in a perfect or highly improved state.

And were it not for the exclusive privilege thus granted, many important inventions, that ultimately prove beneficial to the public, would never be persisted in, but entirely fail; as that powerful incentive would have no existence, which induces ingenious men to study and labour incessantly, and to expend large sums of money to bring their inventions into practical operation.

The basis of the present law of patents is derived from the 21st of James I., ch. 3, which is regarded as the declaration statute; and the sixth section of this statute states, that patents for new inventions are exceptions to the general law of the statute. The general law is, that all monopolies, and all commissions, grants, licenses, letters patent, etc. for the sole buying, selling, making, using, etc. of any thing, shall be void; the excepting clause declares, that "any declaration before mentioned shall not extend to any letters patent, and grants of privilege, for the term of fourteen years or under, hereafter to be made, of the sole working and making of any manner of new manufacture within this realm, to the true and first inventor or inventors of such manufactures, which others, at the time of making such letters patent and grants, shall not use, so as also they be not contrary to law, nor mischievous to the state, by raising the prices of commodities at home, or hurt of trade, or generally inconvenient"

The great importance of the subject of patents to engineers, machinists, and manufacturers in general, renders it desirable to extend this article to an account of the process of obtaining a patent; also the nature and conditions of the grant, and the expenses attending it; which information the writer of this article and compiler of the work is enabled to afford with perfect accuracy, he being professionally a patent agent. It is by no means necessary that the applicant for a patent should employ an agent, - he may solicit the grant himself; there are, however, but few persons whose experience and knowledge of the matter sufficiently qualifies them to transact the business of a patent with security to their own interests.

The first thing an inventor should attend to, is to endeavour to ascertain if he has not been anticipated by others, which is not an unfrequent occurrence, although rarely discovered until too late to benefit by it; owing, perhaps, to the injudicious flattery of friends, or the ignorance of legal advisers in matters of invention or discovery. Having determined.the invention to be entirely original, and that it is calculated to compensate him for the expenses of a patent, the inventor's first step to obtain one, is to make an affidavit of the fact of his invention before a Master in Chancery, if in London, or if in the country, before Master Extraordinary, in the following form; the words in italics being assumed to afford precise examples.

(Form.)

"John Smith, of Birmingham, in the county of Warwick, Iron Founder, maketh oath, and saith, that he hath invented ' certain improved forms of apparatus for the transmission and distribution of heat, the generation of vapours, and other processes,' which he believes will be of public utility; that he is the first and true inventor thereof; that the said invention is entirely new, having never been practised nor used by any other person or persons, to the best of his knowledge and belief. (Signed) "John Smith.

"Sworn at the Public Office in Southampton Buildings, this 6th day of March, 1834, before me, "H. Cross."

Before, however, the affadavit is made or acted upon, the inventor should well consider the nature and words of the title or designation of his invention, for many patents have been annulled owing to the improper wording of the title. The law requires, that it shall form a true index to the specification; yet if it be so clear as to call the attention of rivals, and enable them to discover the secret of the invention, before the patent has passed the great seal, the patentee may lose his privilege as well as his money. If, on the other hand, the title should be so obscure as to incur the danger of a court of justice afterwards ruling that it is an imperfect definition of the invention, he will also forfeit his privilege. Lord Cochrane was thus most arbitrarily deprived of his patent right for the admirable street lamp which bears his name, owing to his having entitled the patent an "improved method of lighting cities, towns, villages." Now when it is considered that no security whatever is afforded to the applicant until his patent has passed the great seal, and that he is, during this period, by too explicit a title, liable to be robbed of his right by impostors, the harshness and injustice of the decision just mentioned becomes very apparent.