extracts, purporting to be certified by the comptroller and sealed with the seal of the Patent Office, of or from patents, specifications, disclaimers, and other documents in the Patent Office, and of or from registers and other books kept there shall be admitted in evidence in all Courts in Her Majesty's dominions, and in all proceedings, without further proof or production of the originals." If the plaintiff sues as assignee, or under any derivative title, and his title is denied, the entry from the register of patents may be proved in the manner suggested by the 89th section. Under the 96th section "a certificate purporting to be under the hand of the comptroller as to any entry, matter, or thing which he is authorised by this Act, or any general rules made thereunder, to make or do, shall be primâ facie evidence of the entry having been made, and of the contents thereof, and of the matter or thing having been done or left undone." For instance, if an entry in the register is denied by the defendant, he may prove its omission by a certificate under the 96th section. If the fact of infringement is denied, the plaintiff must be ready with evidence that the defendant has made, used, or sold the articles or process, and any one of these Acts, as we have already seen, will satisfy the allegation of infringement, whether intentional or not (n). The burden of proving infringement is strictly on the plaintiff, and if he does not satisfactorily prove it there is no necessity of entering upon the defendant's case on other matters. The plaintiff must always give evidence when the alleged infringement is the sale or use of an article, that it was not made by himself or his agents (0). The plaintiff must, if the matter be put in issue, prove that the title, provisional specification and complete specification, correspond and substantially describe the same invention (p). If it is alleged by the defendant that the invention is illegal or useless, the burden of proof is on the plaintiff. So the plaintiff must be prepared, if he intends to claim (n) See Chap. XVII. (0) Betts v. Willmott, L.R.,6 Ch. 239. (p) Ante, p. 78, et seq. damages, and not an account, to prove the damage which he has sustained (). When the defendant alleges that there is a defect or insufficiency in the specification, the burden of proving that there is no such defect is on the plaintiff. We have seen (r) that it is for the jury to say whether a specification is sufficient or intelligible or not; it is for the Court to place a construction upon the language used in the specification. The plaintiff must therefore be prepared with evidence of an expert character as to the sufficiency of the specification; and in selecting this evidence the plaintiff cannot be better guided than by the judgment of Sir George Jessel in Plimpton v. Malcolmson (s); he must not select eminent engineers or celebrated chemists as the persons to whom the specification must be intelligible, but he must choose "ordinary workmen " in the particular branch of trade to which the invention refers-" not a careless man, but a careful man, though not possessed of that great scientific knowledge or power of invention which would enable him by himself unaided to supplement a defective description or correct an erroneous description." He may, of course, call eminent engineers, but their evidence can only be, "placing myself in the position of an ordinary workman I think it would or would not be intelligible or sufficient to me." If the specification be not sufficiently clear to be understood by an ordinary workman (a witness for the plaintiff), witnesses will not be allowed to be called to explain the intention of the patentee, and the plaintiff will be non-suited (t). An expert witness cannot be asked his opinion as to whether or not there has been infringement. That is a question for the jury, or the Court in the absence of a jury (u). The description of evidence which is admissible in an action for infringement has been considered in an earlier chapter (v); questions, however, which may be put to an expert witness in exami nation in chief differ to some extent from those which may be put in cross-examination. When the witness has stated in his examination that an ordinary workman would make a certain machine from the description contained in the specification, it is open to the counsel on the other side to cross-examine him upon the specification, taking it line by line for the purpose of showing that what he said in the first instance was incorrect, although that method of questioning would not be permitted on examination in chief. The Court will consider the circumstances of the case, the behaviour of the witnesses and their credibility, when considering the question of infringement or no infringement. In Clark v. Adie (r), Lord Blackburn said:-" Whenever a man knowing for the first time of an invention, either by seeing a machine at work or by reading a specification, proceeds to do what he never did before, and takes a part of the invention, it is always a very strong argumentum ad hominem to say: You are, by the very fact of taking this, making evidence against yourself that it was a new invention; otherwise, why did you take it? You are making evidence against yourself that at all events the part you took was new, or why did you take it? and whenever there is a case of theft or stealing knowingly, that observation ought to have some weight, although I think in practice it has more weight given to it than it ought to have. But where there is a case of an innocent infringement of property, by an unwitting use of this sort, that observation can have no weight against the party in the slightest degree, and I think it ought not to have any." Experiments conducted for the express purpose of manufacturing evidence, with a view to litigation, are to be looked at with distrust (y). When the defendant pleads that the grantee of the letters patent was not the true and first inventor, or that the invention was not new, it will be sufficient if the plaintiff gives some primâ facie evidence of novelty (z). It will be sufficient to call one or (2) L. R., 2 App. Cas. 337. Westley Richards v. Perkes, 10 P. O. R. 181, 186. two persons acquainted practically with the trade to which the invention refers, to say that they never heard of it, or saw or heard of its having been put in practice or published before the date of the patent. Gibbs, C.J., said: "The first witness, a man of considerable experience, had never seen locks with the lips so perforated; primâ facie that is good evidence; but when the question is, whether this had existence previous to the patent, fifty witnesses proving that they never saw it before, would be of no avail if one was called who had seen it and practised it (a). The plaintiff having given this primâ facie evidence, the burden of proof as to prior user or prior publication is shifted to the defendant, and if he would invalidate the patent he must prove his case. We have previously discussed what amounts to prior user and prior publication (b). The evidence which the defendant brings must be complete and satisfactory, and the question is one of fact. If the defendant has succeeded in establishing a case against the plaintiff, the latter will be permitted before the defendant sums up, to adduce rebutting evidence. In Penn v. Jack and Others (c), Sir W. Page-Wood, V.-C., said: "I think the plaintiff is entitled to adduce evidence, in reply, for the purpose of rebutting the case set up by the defendants; and for this reason that it is quite impossible for him to know what is the nature of the evidence which is to be produced. The defendants, who contest the validity of the invention, have in effect put in a plea denying the novelty of the plaintiff's patent; and the affirmative of the issue just raised in reality rests with the defendants who are not obliged to give the names of their witnesses. How can the plaintiff possibly meet such a case until he hears the evidence for the defence, and knows what their witnesses will prove? should be very sorry to have to put the parties to all the expense and delay of a new trial, which I should have to direct, if this evidence were excluded. Besides which, the witnesses are at hand and ready, and the sensible and obvious course is to examine them now. The practice at common law is stated in Taylor on (a) Manton v. Manton, Dav. P. C. 350. (b) Ante, Chap. V. (c) L. R., 2 Eq., at p. 317. I Evidence; and it appears that where, as here, several issues are joined, the plaintiff may content himself with adducing evidence in support of those issues which he is bound to prove, reserving the right of rebutting his adversary's proofs, in the event of the defendant establishing a primâ facie case with respect to the issues which lie upon him. In support of this proposition, Shaw v. Beck (d) is cited, where Parke, B., used the following expression: But Abbott, C.J., laid down what appears to me to be a more reasonable rule, by holding that the defendant was bound to prove his plea, and that the plaintiff might answer it by additional evidence.' Other instances are also mentioned, all showing the wide discretion given to the judge in allowing evidence to be given by the plaintiff in reply. The plaintiff has put in his letters patent as formal evidence of his title. The defendants then plead want of novelty, and give, in proof of the issues thus raised by them, special evidence, which the plaintiff is entitled to rebut, by evidence in reply. Regarding this case as one of an affirmative plea, the burden of proving which rests on the defendants, I feel bound to admit the evidence proposed to be given by the plaintiff in reply.” Although the plaintiff may, as of right, rebut the case made by the defendant, upon any issue which rests with the defendant, where the plaintiff has given such rebutting evidence, the defendant will not be allowed to strengthen the case which he had made by adducing further evidence; and this will apply with greater force when the defendant's counsel has summed up the evidence which has been offered (e). At the hearing of the action, no objection will be allowed either to the particulars of objections, or to the particulars of breaches, and any evidence will be received which they are wide enough to admit of. If there is any vagueness or insufficiency in the particulars, the party requiring further information must apply for it to a judge in chambers, within reasonable time before the trial of the action; but they will not be allowed to permit the opposite side to go to trial, and then to submit that for want of sufficient particularity in the objection, the evidence is not admissible (ƒ). (d) 8 Ex. 392. (e) Penn v. Jack, L. R., 2 Eq., at p. 318. (f) Ante, pp. 290, 301. |