and in some cases to insert covenants on the part of the patentee to proceed against persons infringing the patent (see Henderson v. Mostyn, L. R. 3 C. P. 202), or to permit the licensee to proceed in the patentee's The Court will grant an injunction at the suit of exclusive licensees (Renard v. Levinstein, H. & M. 628).

name.

When a sum of money has been paid for a licence, and the consideration fails, the money may be recovered. Thus in Knowles v. Bovill (22 L. T. N. s. 70), it appeared that a patentee had granted to the plaintiff a licence to use his patent, and had agreed to apply for a prolongation of the patent of which the plaintiff was to have the benefit; and he further agreed to grant a licence under a new patent for which he had applied. The patentee, however, died shortly afterwards without having done anything. It was held that the plaintiff could recover the money paid from the patentee's executors. On the other hand, it has been decided that money paid in consideration of a licence cannot be recovered by action when the patent turns out to be void (Taylor v. Hare, 1 Bos. and Pul. N. R. 260); except where fraud is proved (Lovell v. Hicks, 2 Y. and C. 472). To meet this case it will be prudent to have a covenant in the licence, under which the parties may readjust their accounts in the event of the patent proving void or voidable.

A licensee during the continuance of the licence cannot set up as a defence to an action for the royalty that the invention was not new or not useful, or that the patentee was not the first inventor, or that the specification is insufficient (Noton v. Brooks, 7 H. & N. 499; Trotman v. Wood, 16 C. B. N. s. 479; Smith v. Scott, 5 Jur. N. s. 1356; Chavasse v. Stevens, W. N. 1874, p. 193; Adie v. Clark, L. R. 2 App. Cas. 423; Liardet v. Electric Lighting Co., W. N. 1883, p. 96).

But when in such a case the claim in the specification is susceptible of two constructions, one of which would make the specification bad, and the other and more natural one would make it good, it was held that the licensee may insist that the latter is the true construction (Trotman v. Wood, 16 C. B. N. s. 479). But now see Adie v. Clark cited above. Even where no formal licence has been executed, a person who has paid money in the nature of a royalty will not be allowed to dispute the validity of the patent (Crossley v. Dixon, 10 H. L. C. 293). Neither will a patentee, after assigning all his interest in a patent for a valuable consideration, be allowed, in an action against himself for an infringement, to raise the question whether the patent is void for want of novelty (Walton v. Lavater, 8 C. B. N. s. 162, 187; and see also Chambers v. Crichley, 33 Bea. 374). Furthermore, a licensee will not be permitted to use the invention without payment of the royalties he has covenanted to pay, even after the patent has been found invalid in proceedings between other parties (The Grover & Baker Sewing Machine Company v. Millard, 8 Jur. N. s. 713). But where judgment was given by consent before declaration filed in an action. by a patentee against the members of a partnership firm for an alleged infringement, and the defendants immediately took a license to use the invention, and the patentee subsequently instituted a suit to restrain infringement against the defendants at law and two fresh partners, it was held that the defendants in equity were not estopped from disputing the validity of the patent (Goucher v. Clayton, 11 Jur. N. s. 107).

A licensee has, however, a right to have it ascertained what is the field covered by the specification as properly construed, and is entitled to say that he has not gone inside that field. He may seek to have the boundary of the patentee's invention defined with the

view of showing that he had not rendered himself liable to make the payments stipulated in the licence. (Adie v. Clark, L. R. 4 App. Cas. 423). And after a licence has been determined, a licensee is at liberty to dispute the validity of a patent in a suit for an injunction to restrain an infringement (Dangerfield v. Jones, 13 L. T. N. s. 142; Axmann v. Lund, L. R. 18, Ch. D. 330; and see Neilson v. Fothergill, 1 W. P. C. 290).

It was held by Lord Romilly, M. R., in Mathers v. Green (34 Beav. 170), that when one of three joint patentees had granted licences, he was bound to account to his co-patentees for the royalties received.

An exclusive licensee has a right to apply in the name of the owner of the patent for an injunction to restrain infringements (Renard v. Levinstein, 2 H. & M. 632); but an ordinary licensee has not such a right (Newby v. Harrison, 1 J. & H. 393), nor has the agent of the patentee (Adams v. North British Railway Company, W. N. 1873, p. 191).

A patentee will not be allowed to publish advertisements and circulars calculated to deter the public from dealing with his licensee (Clark v. Adie, 21 W. R. 764).

Formerly when the patent was silent as to the form of licence, a simple licence, without covenants, need not have been under seal (Chanter v. Dewhurst, 12 M. & W. 823; Reuss v. Lever, Ch. Div. April 9, 1879, V. C. Hall); nor, it seems, if it was not a deed, did it require a stamp (Chanter v. Johnson, 14 M. & W. 408). But now the form of patent set forth in the first schedule of the Act requires licences to be in writing under the hand and seal of the patentee. A stamp of 10s. must be impressed in ordinary cases, and an ad valorem stamp on the consideration-money when a fixed sum is paid. When a licence contains a covenant for the payment of a minimum royalty, the Stamp Office insists

upon payment of an ad valorem duty upon the gross minimum royalty reserved, and this although the licence contains power for licensor or licensee to determine the licence.

Whether a licence not under seal was revocable or not depended on its construction (Reuss v. Lever, Ch. Div. April 9, 1879, cited above).

As to the procedure on the registration of licences see Rule 74 of the Patents Rules 1883 and Form M in the second schedule.

CHAPTER XIII.

THE REGISTRATION OF PATENTS, ETC.

THE twenty-third section of the Patent Act of 1883, directs that there shall be kept at the Patent Office a book called the Register of Patents, wherein shall be entered the names and addresses of grantees of patents, notifications of assignments and of transmissions of patents, of licences under patents, and of amendments, extensions, and revocations of patents, and such other matters affecting the validity or proprietorship of patents as may from time to time be prescribed. The Register of Patents will be primâ facie evidence of any matters by the Act directed or authorised to be inserted therein. Copies of deeds, licences, and any other documents affecting the proprietorship in any letters patent or in any licence thereunder, must be supplied to the Comptroller in the prescribed manner for filing in the Patent Office.

By the eighty-seventh section of the Act, where a person becomes entitled by assignment, transmission, or other operation of law to a patent, the Comptroller shall on request, and on proof of title to his satisfaction, cause the name of such person to be entered as proprietor of the patent, in the Register of Patents. The person for the time being entered in the Register of Patents, as proprietor of a patent, shall, subject to any rights appearing from such register to be vested in any other person, have power absolutely to assign,