patent obtained by the plaintiff and alleged to be infringed by the defendants.

The defendants in an action for the infringement of a patent belonging to persons who previously to their becoming the owners of it had in various proceedings disputed or made preparations for disputing its validity applied to the Court for an order for the inspection of certain documents relating to those proceedings. It was held by a Divisional Court that the defendants were entitled to have inspection of all except such as the plaintiffs should state on oath had come into existence merely to be communicated to the solicitor for the purpose of litigation actual or intended, and either as materials for briefs or for his advice and consideration. (Haslam Co. v. Hall, 5 R. P. C. 1.)

Litigation had taken place between two companies with regard to the validity of a patent belonging to one of them. They afterwards amalgamated and the new company brought an action for infringement against H. It was held by the Court of Appeal that H. was entitled to administer an interrogatory as to the particulars of objections delivered in the previous action between the two companies. (Edison & Swan Co. v. Holland, 5 R. P. C. 213.) In this case (p. 216), the practice with regard to applications for leave to administer interrogatories having reference to documents supposed to be in the possession of the opposite party, who has already given discovery, is stated.

Where it seems probable from a document produced by one of the litigating parties that he has in his possession other relevant documents, he may be called upon to make a further affidavit in regard to those supposed documents. (Bown v. Sansom, 5 R. P. C. 515.)

The Trial. Under the twenty-eighth section of the Act of 1883 the action is to be tried without a jury unless the Court shall otherwise direct. Trials of patent cases have very seldom taken place before juries since the Act came into operation.

By the Arbitration Act 1889 (52 & 53 Vict. c. 49 s. 14) repealing and re-enacting with slight variations the fifty

seventh section of the Judicature Act of 1873, the judge before whom a case requiring scientific investigation' comes for trial is empowered to send the issues of fact to be tried before a referee. Where a patent case had been so sent for trial before an official referee, it was contended by the plaintiff in the Court of Appeal that the case was not one that required scientific investigation' within the meaning of the Judicature Act, but it was held to be impossible for that Court to say that an action for the infringement of a patent did not require scientific investigation; and that, as the judge had decided that it did, the Court would not interfere with his discretion. (Saxby v. Gloucester Waggon Co., W. N. 1880, p. 28.)

The referee will make a report as to the issues of fact which were sent to him for trial, and his findings so reported are to be considered equivalent to the finding of a jury.

On the trial of an action for the infringement of a patent the Court has power, under the Arbitration Act 1889, repealing and re-enacting with variations sect. 56 of the Judicature Act of 1873, to order without the consent of the parties that a competent person should ascertain facts or make experiments, and report the result of his inquiry for the information and guidance of the Court. (See Badische Anilin und Soda Fabrik v. Levinstein, L. R. 24 Ch. Div. 156; Mellin v. Monico, L. R. 3 C. P. D. 142; Edison & Swan Co. v. Holland, 5 R. P. C. 459.) The Court of Appeal sometimes thinks fit to exercise this power. (Moore v. Bennett, 1 R. P. C. 129.)

By the twenty-eighth section of the Act of 1883 it is enacted that, in an action or proceeding for infringement or revocation of a patent, the Court may, if it thinks fit, and shall, on the request of either of the parties to the proceeding, call in the aid of an assessor specially qualified, and try and hear the case wholly or partially with his assistance. Under the third subsection of the same section the remuneration, if any, to be paid to such assessor shall be determined by the Court and be paid in the same manner as the other expenses of the execution of the Act.

By the nineteenth section of the Act of 1883 the judge is empowered, in an action for infringement or in a proceeding for revocation, to give liberty to the patentee to apply at the Patent Office for leave to amend his specification, and to postpone the trial. (See the chapter on Amendments.)

As to the trial of causes and issues, see Order XXXVI. Rule 5 and Rule 7 (a) of the Supreme Court Rules, 1883.

The defendant in an action for the infringement of a patent for a chemical process set up by his defence that he had a secret process which was not an infringement. The judge, seeing that irreparable mischief would be done to him if he were called upon to state in open Court what that secret process was, in case it should turn out that the patent. was bad, allowed him not to answer certain questions which were put to him, but left him to determine for himself whether he would or not communicate his secret process to the Court, so that the Court might be able to determine whether he infringed the patent or not. The defendant, acting on the advice of his counsel, elected before the termination of the case to disclose his secret to the judge, who heard his description of it with closed doors, no persons being present except the parties and their scientific assistants. (Badische Anilin und Soda Fabrik v. Levinstein, L. R. 24 Ch. D. 156.) See also Edison v. Woodhouse (3 R. P. C. 172).

A model which has not been put in evidence may be handed up to the Court as an example of a class of machine, in order to explain counsel's argument. (Boyd v. Horrocks, Appeal, 6 R. P. C. 154.)

Where a judge at the trial of an action is of opinion that the invention under the patent is good subject-matter and is useful, and accordingly upholds the patent in these respects, his decision will be followed by another judge of co-ordinate jurisdiction in case the validity of the same patent is contested on the same grounds by another defendant. (Slazenger v. Feltham, 6 R. P. C. 132; S. C. on appeal, 6 R. P. C. 234.)

Evidence. In regard to the evidence it may be useful to remember that the Court looks with distrust on experiments conducted for the express purpose of manufacturing evidence for the cause. (Young v. Fernie, 5 Giff. 577; Betts v. Neilson, L. R. 3 Ch. 429, 453.)

By the 4th subsection of the 29th section of the Act of 1883, no evidence is to be admitted at the hearing, except by leave of the Court or a judge, in proof of any alleged infringement or objection of which particulars have not been delivered.

Hence under this clause the Court at the trial has a discretionary power to allow the evidence to go beyond the particulars of breaches or objections. (Britain v. Hirsch, on appeal, 5 R. P. C. 226.)

Where particulars of breaches alleged divers sales and specified sales to two persons, evidence of a sale to a third person was allowed where the defendant admitted having had transactions with him. (Sykes v. Howarth, L. R. 12 Ch. D. 827.)

As to the mode of proving the allegation of general public knowledge, see the case of Holliday v. Heppenstall, ante, p. 280, under Particulars of Objections.

In actions for infringement the onus of proof with regard to want of novelty is on the defendant, and therefore in an uncontested case the plaintiff is not bound to prove the novelty of his invention. (Peroni v. Hudson, 1 R. P. C. 261.)

An offer to execute orders for swivelling pumps in response to applicants, no particular form of swivelling pump being mentioned, was held not to be evidence of an intention to infringe a patent for swivelling pumps where the specification did not claim every kind of that class of pump. It was to be presumed that the offer referred to such pumps as would not be an infringement of the patent. (Gwynne v. Drysdale, 2 R. P. C. 160; S. C., appeal, 3 R.P.C. 65.)

It was said by Lord Herschell in the House of Lords. (Badische Anilin und Soda Fabrik v. Levinstein, 4 R. P. C.

465), that neither the patentee nor any other witness could be called to prove what was the invention claimed by the specification. That question was to be answered from a critical examination of the instrument by the Court. It would seem, therefore, that the cases of Bateman v. Gray (Macr. P. C. 111) and Crossley v. Potter (Macr. P. C. 255) are overruled as far as they relate to this point.

A patentee who has assigned his patent cannot be restrained, on the trial of an action for infringement brought by the assignee against a third party, from giving information in his possession which might tend to show that the patent is invalid. (London and Leicester Hosiery Co. v. Griswold, 3 R. P. C. 251.)

A plaintiff is entitled to adduce evidence in reply for the purpose of rebutting the case set up by the defendant. (Penn v. Jack, L. R. 2 Eq. 317.)

As to the circumstances under which the Court of Appeal will admit or refuse further evidence in patent cases under Order LVIII., Rule 4, of the Supreme Court Rules, 1883, see Hinde v. Osborne (2 R. P. C. 45); Watling v. Stevens (3 R. P. C. 147); Walker v. Hydro-Carbon Syndicate (3R.P.C. 253); American Braided Wire Co. v. Thomson (5 R. P. C. 118); Britain v. Hirsch (5 R. P. C. 226); Spencer v. Ancoats Vale Rubber Co. (6 R. P. C. 46); Blakey v. Latham (6 R. P. C. 184).

The opinion of scientific witnesses is only admissible as proof of facts. Their opinion whether there has been an infringement or not, though sometimes received in order to save time, is strictly speaking inadmissible, and if objected to ought to be rejected. The Court alone is to decide questions of law. Per Lord Wensleydale, in Seed v. Higgins (8 H. L. C. 550). See also Westinghouse v. Lancashire and Yorkshire Railway Co. (1 R. P. C. 229). But although it is not for a witness to construe a specification, it is allowable to ask him in an ordinary way what he understands by it. Per Lord Halsbury, C., in Kaye v. Chubb (5 R. P. C. 650).

In regard to the proof of documents in the Patent Office,