a subject from a drawing without a scale, the scale has been declared not essential, and the introduction of French words, such as vis de pression, vis de repulsion, &c., for certain screws, and even French measures instead of English, have been held not to invalidate a patent when they were found to be immaterial to a complete understanding of the invention.

43. Effects that do not result must not be described. Not only must no unnecessary means be mentioned, but effects that do not actually result must not be described. If the article described have not the qualities or results set forth, the grant is invalid.

44. Plural instead of singular fatal to a patent. Where a patent for an improvement in the hautboy spoke of new notes, whilst only one new note was produced by the invention, an action for infringement failed.

45. Omission of essential part of operation fatal to a patent. — In a patent for steel trusses, the patentee having omitted to mention that he tempered the steel with tallow, and such an operation having been proved useful, the patent was held to be void. Where aquafortis was used in the preparation of verdigris, and not mentioned in the patent, the patentee using it with great secrecy, the presumption was arrived at that he knew of the value of such application on taking out the patent, and it was consequently declared to be void.

46. Unnecessarily expensive materials described fatal to a patent. If cheaper materials be used by the patentee than those described in the patent, it is bad. And even where a patentee omitted to describe an essential part of his invention through inadvertence, his neglect was held fatal to the grant.

47. Better method, fruit of subsequent discovery, not

fatal. But if a better method of manufacture can be proved to have been a subsequent discovery, the patent will not be affected thereby.

48. Full description of machinery and the relative parts, &c., necessary.—In a piece of machinery a full description of the several parts, as wheels, screws, springs, &c., must be set forth with their due proportions, the method of their union, and the relative velocities of the movable parts.

49. If composed of two machines, union, &c., must be shown. Where the invention consists of the component parts of two machines, or more, the union of the parts must be clearly shown. If parts are to be put on and off during the operations the respective parts, their proportions for different purposes, and where they are to be applied, must be stated.

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50. Latitude allowed in descriptions. The inventor is not bound to any particular mode of describing his improvement, provided he exactly states in what the invention consists. Thus, a patentee was declared to have complied with the law when he referred to a common watch, and then gave directions how the new part was to be added to it, the invention consisting of a single movement.

51. Patentee may recite former specification. — A patent for an improvement on a previous patent, obtained by the same inventor, was held good, in which the former patent was recited, though in the specification no reference was made to the description of the former subject, and the whole machine, as improved was set forth without the new parts being distinguished from the old. The reason for the decision was, that the second patent, by reciting the first, referred to its specification, which, being a matter of record, was supposed

to be within every one's knowledge. Although in this case the patentee referred to his own patent, it would follow by analogy that a person making a manufacture from the subjects of several expired patents might recite and refer to the specifications of them without taking any notice of their contents.

52. Caveats. A caveat is an instrument by which notice is requested to be given to any person having imagined butnot thoroughly completed an invention, whenever another person shall apply for a patent for such an invention. The contemplated invention must be described in general terms. Copies of the caveat must be left both with the Attorney and Solicitor General, and must be annually renewed. A caveat does not create any right; it is simply a request to be favoured with information which may enable the person lodging it to oppose the grant of a patent to any other person who shall claim protection for the invention which is the subject of the caveat. If the applicant thinks that he is unjustly deprived of his patent after being duly heard, he has no remedy but a scire facias to repeal that which has been sealed. It having been generally observed that little or no benefit arises from entering caveats, the practice has become obsolete.

53. Consideration paid for patent not recoverable though patent bad. The patentee of an invention which he believed to have been new transferred it for a valuable consideration to another, and the grant having afterwards proved to have been bad, it was held that the assignee, having used the patent for some time, could not recover the amount paid for his purchase, the vendor having acted without fraud in the transaction. However had the patent been discovered to be invalid before the assignee had made any use of it, it would

appear that the purchase money ought to be returned.

54. Patent passes to assignee of bankrupt.-Property in a patent passes to the assignees of a bankrupt or insolvent, and a grant obtained by an uncertificated bankrupt also vests in his assignees for the benefit of his creditors.

55. Patent passes to legal representative of deceased.A patent may be bequeathed according to the pleasure of the patentee. If he die intestate it becomes assets in

the hands of his administrator.

56. Patentee may license. A patentee may grant licences for the sole or partial use of a patent, and the licencees may maintain actions for damages.

57. Penalty for using name, &c., of patentee. The 5 and 6 Wm. IV. c. 83, s. 7, gives a penalty of 50l. against a party using the name, &c., of a patentee.

58. Patent void if contrary to law. Besides the grounds for nullity already specified, a patent is, by the Statute of Monopolies, void ab initio if contrary to law or mischievous to the state.

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PATENT OFFICE, LIBRARY, AND MUSEUM.

CHAP. III.

THE PATENT OFFICE, LIBRARY, AND MUSEUM.

THE present Patent Office occupies the ground floor of the Masters' office in Southampton Buildings, Chancery Lane, formerly the chambers of the masters in Chancery, and for which the Commissioners of Patents pay an annual rent of 4907. out of the Fee Fund of the Patent Office to the Suitors' Fund of the Court of Chancery.

In 1855 a free library was established within the office, containing scientific works in all languages, the publications of the Commissioners, and the works upon patented and other inventions published in the British colonies and in foreign countries. This library has been formed partly by purchases, but in a great measure by gifts and loans of valuable and useful books.

It is open gratuitously to the public between 10 and 4 daily, and is admirably managed, the only defect being the want of sufficient space for the books and the public.

The deficiency, in respect to space, both for the library and the other offices, is lamented by the commissioners, who are endeavouring to find a suitable site, in the immediate neighbourhood of the present Patent Office, for the erection of a building amply sufficient for the requirements of the office.

In a portion of the museum at South Kensington, which was assigned to the Commissioners of Patents by the Board of Trade, are daily exhibited gratuitously to