considerable loss from his patent. It was shown, moreover, that the Admiralty had then lately instituted experiments with a view to the adoption of the invention, and that several friends of the inventor were willing to provide large capital for working the invention, should a prolongation be obtained. Evidence was also given that from the nature of the invention it would necessarily be a long time before its merit could be properly brought before the public. Under these circumstances the Judicial Committee (stating that they considered the case exceptional) granted a prolongation for the unusual period of ten years.

In the case of Sillar's Patent (Goodeve's cases, p. 581), it appeared that the patent had been sold by the patentees to a Joint Stock Company, who had paid them a sum which seemed to be commensurate with the value of the invention. The company had afterwards floated their shares in the market, and had thereby made considerable profit. They then applied for an extension of the patent, but it was refused, although they had been considerable losers by working the invention.

Major Childs obtained a patent in 1869 for improvements in the manufacture of bread and biscuits. By this invention a nutritious aërated bread could be made by machinery with regularity and certainty. Down to 1873 the inventor had failed in his endeavours to get the invention fairly worked, but in that year he became chairman of the Aërated Bread Company, and let them have the use of his patent. It was not until 1883 that a large central manufactory was started in London for the making of bread by his process. He received a salary of 600l. as chairman and managing director of the company, which was paying 8 per cent. on the shares, of which he held 12,000. The counsel appearing for the Crown estimated that the inventor had made a profit under the patent of between 20,000l. and 30,000l., including the rise in the value of the shares held by him. The Judicial Committee were satisfied that the invention possessed considerable merit, and, although the inventor had made for the last five years a profit which

was increasing, they came to the conclusion that he had not been sufficiently remunerated, and a prolongation for five years was granted. (Childs's Patent. The Times,' Dec. 1883.)

A petition for a prolongation of Deacon's two patents obtained for improvements in measuring the flow of water through pipes was presented in 1887. The accounts showed that the patentee had made a profit of 6,000l., and that he had besides an interest in a public company to which the patents had been assigned. The invention being very meritorious, an extension of three years was recommended. (4 R. P. C. 119.)

Nussey and Leachman in 1876 obtained a patent for improvements in machinery for pressing fabrics. An application for its extension was heard in December 1889, when their lordships, remarking that they could not say there had been no utility, but finding there had been a net profit of 4,000l., and looking at the degree of merit and amount of remuneration, declined to report that the patentees had not been adequately remunerated. It was also stated that the Privy Council had taken into consideration the fact, although they had not decided the case wholly upon it, that the petitioners had got new letters patent for improvements upon the patent, which had almost shut out the use of that patent. (7 R. P. C. 22.)

The exceptional period of ten years was granted in the case of Stoney's Patent (5 R. P. C. 518), where it appeared that the invention possessed considerable merit, but had a very small scope for its employment, whilst the patentee had derived no profit from it. This was a patent for improvements in sluices and floodgates. Mr. Justice Groves' instructive judgment may be usefully consulted with reference to the case which a petitioner for an extension ought to make out before the Privy Council.

CHAPTER XV.

ASSIGNMENTS AND LICENCES.

POWER both to assign and to license is by implication given to the patentee by the patent.

It is desirable to register both assignments and licences as soon as may be after their execution. If his assignment is not registered an assignee cannot maintain an action for an infringement against third parties except licensees from the assignor subsequent to and with notice of the assignment. See Chollet v. Hoffmann (7 E. & B. 636); Hassall v. Wright (L. R. 10 Eq. 510), cases under the old law. See the Chapter on Registration, and Rules 67-72 and 77 of the Patents Rules 1890.

Rules 67 to 72 prescribe a somewhat complicated system of registry for assignments and licences. In all cases there must be a request in writing to the Comptroller to register, and the original document to be registered, together with an attested copy, must be left with the Comptroller. The practice of registration under the Act of 1852 was quite as effective and much more simple.

ASSIGNMENTS.

To be a valid instrument, an assignment ought to be a deed under hand and seal. It is usual to introduce into assignments covenants on the part of the patentee that he is the true and first inventor, and that the patent is valid. In those cases where the assignor does not part with his entire interest in and under the patent it may be well to insert a covenant binding him not to seek leave to amend the specification or drawings without the written consent of the assignee.

Under the twenty-fifth section of the Patents Act of 1852, a patent obtained in the United Kingdom for an invention previously patented in a foreign country came to an end at the expiration of the foreign patent. But as this provision has not been inserted in the Patents Act of 1883, it is not now of importance for an assignee to see that the foreign patent is kept on foot, although when the assignment deals with a British patent obtained under the Act of 1852 it is still incumbent upon him to see that the foreign patent had not expired prior to January 1, 1883.

A patentee is empowered, by the thirty-sixth section of the Act of 1883, to assign his patent for any place in or part of the United Kingdom or Isle of Man as effectually as if the patent were originally granted to extend to that place or part only.

This provision seems to be of very doubtful utility, and prudent patentees may well hesitate to make assignments. under it. To assign a patent for a place or district might not improbably land both parties in grave difficulties which do not all lie on the surface.

It is no answer to an action to enforce a contract for the purchase of a patent for a stipulated sum (Hall v. Conder 2 C. B. N. s. 22) to plead that the patent is wholly worthless and of no utility, and that the subject-matter of the patent was not the novel invention of the plaintiff, there being no proof of fraud, and no express warranty. Such a contract was held merely to have the effect of placing the purchaser in the same situation as the seller was with reference to the patent, and the purchaser is bound to take it with all its faults. This being so, it is desirable to consider whether or not an express warranty of the patent should not be introduced into contracts of this nature. See also Smith v. Neale (2 C. B. N. s. 67).

The purchaser ought invariably to have a search made by a competent person at the Patent Office and elsewhere as to the novelty of the invention, prior to his entering into a contract for the purchase.

One of two or more joint patentees cannot assign more

than his share of the patent. (In Re Horsley and Knighton's Patent, L. R. 8 Eq. 475).

The assignee of part of a patent separate from other parts may bring his action for an infringement of such part without joining as plaintiffs those persons who have distinct interests in the other parts, but have no interest in the damages sought to be recovered. (Dunnicliff v. Mallet, 7 C. B. N. s. 209.) This decision was mentioned with approval by the Court when delivering judgment in the case of Walton v. Lavater (8 C. B. N. s. 184), where it was unsuccessfully contended that the assignee of an undivided share of a patent had not a sufficient legal interest to sue for its infringement.

It has been held that one co-owner of a patent may sue alone for the recovery of profits due for the use of the patent without making his co-owners parties. (Sheehan v. G. E. Ry. Co., 16 Ch. D. 59.) (See, however, Van Gelder &c. Co. v. Sowerby, 7 R. P. C. 41.)

The assignee of a share of the profits of the patent is entitled to call on a licensee of the patentee for an account, but the assignee suing must make the assignor and the assignees of other shares of the profits parties to the suit, and must offer to pay any moneys due from the assignor to the accounting licensee. (Bergmann v. Macmillan, L. R. 17 Ch. D. 427.)

The assignee of the original assignee takes subject to his covenants if he has notice of them. (Werderman v. Société Générale d' Electricité, L. R. 19 Ch. D. 247.)

Where a patent is assigned to two persons and one dies, the survivor may sue for an infringement committed during the lifetime of the other. (Smith v. London and NorthWestern Railway Company, 2 E. & B. 69). In the event of a patentee's bankruptcy, the patent becomes vested in the trustee, who may sue for infringements committed before the bankruptcy. (Hesse v. Stevenson, 3 Bos. & P. 577; Bloxam v. Elsee, 9 Dowl. & R. 215; S. C. 6 B. & C. 169.)

Where a partnership at will was formed for the purpose of working an invention for which a patent had been previously obtained and registered in the name of one of the