or of copies or extracts from such documents, see Chapter XXIII.

Functions of the Judge and Jury at the Trial.—When a patent case is tried before a jury it is the duty of the judge, where a specification comes into question, to explain to the jury what that instrument directs to be done, and it is for the jury to say whether, upon the evidence, the promised result will be accomplished by pursuing those directions. (Per Cresswell, J., in Beard v. Egerton, 8 C. B. 165; 19 L. J. C. P. 36.)

The construction of a specification belongs to the Court alone, but if the case is tried before a jury, then the attendant circumstances and the true meaning of the technical phrases, if there be any, are questions which must be ascertained by the jury. (Neilson v. Harford, 1 W. P. C. 370; Bovill v. Pimm, 11 Ex. 718; Otto v. Linford, Court of App. 46 L. T. N. s. 35; United Telephone Co. v. Bassano, 3 R. P. C. 295.) Where novelty or infringement' (said Lord Campbell, in Seed v. Higgins, 8 H. L. C. 561) 'depends merely on the construction of the specification, it is a pure question of law for the judge; but where the consideration arises how far one machine imitates or resembles another in that which is the alleged invention, it generally becomes a mixed question of law and fact which must be left to the jury.' It is also for the Court to decide the question as to the identity of inventions described in two nearly contemporaneous specifications, when such questions can be determined by a simple comparison of the specifications. (Per Coltman, J., in Allen v. Rawson, 1 C. B. 571; per Pollock, C. B., in Tetley v. Easton, at Nisi Prius, Macr. P. C. 68; and per Erle, J., in Bush v. Fox, Macr. P. C. 168; Booth v. Kennard, 2 Hurlst. & Norm. 84; Thomas v. Foxwell, 6 Jur. N. s. 271; Hills v. London Gas Light Company, 5 Hurlst. & Norm. 312. See, however, the observations of C. J. Tindal, in Muntz v. Foster, 2 W. P. C. 105.) But if anything more than simple comparison is required to determine the identity or dissimilarity of two

U

inventions, the question must be submitted to the decision of the jury.

'We by no means lay down as a general rule' (said Lord Campbell, C. J., in Thomas v. Foxwell, 5 Jur. N. s. 37) that upon a question of novelty of invention such as this, raised by the comparison of two specifications, it must necessarily be a question of law for the Court. The specifications may contain expressions of art and commerce upon which experts must be examined, and there may be conflicting evidence, raising a question of evidence to be determined by the jury. But it is quite clear that there may be cases in which the Court would be bound to decide the question of novelty exclusively, for the two specifications might be, in ipsissimis verbis, the same; and if they be in such plain and common language that the judge is sure he understands their meaning, he is bound to construe them as he does other written documents.' 'If there be two specifications to be compared' (said Lord Westbury, C., in Hills v. Evans, 4 De G. F. & J. 288-298), in order to arrive at a conclusion of fact, the right of drawing the inference of fact from the comparison belongs to the jury, and is a question of fact, and not a question of law.'

Steiner obtained letters patent for a new manufacture of a certain colouring matter called garancine, extracted from madder-root, and extensively used in dyeing. This colouring matter was formerly extracted by simply boiling the root in water, and the refuse matter, termed 'spent madder,' was thrown aside as useless. Steiner's process, under his first patent, obtained in 1832, was the employment of diluted sulphuric acid of a given strength, and he proposed to apply it to the extraction of the colouring matter from both fresh and spent madder. In 1843 Steiner took out another patent, specially applicable to the extraction of garancine from spent madder. A much stronger solution of sulphuric acid was now used, and heat was employed. He thus obtained a large portion of the garancine which had previously remained attached to the woody fibre. C. B. Pollock, at the trial of an action brought for

an infringement of the latter patent (Steiner v. Heald, 2 Car. & Kir. 1033), said, 'It appears to me that this is precisely the same as if you applied a process to grapes already imperfectly squeezed, by which you squeeze a little more juice out of them than was formerly done.' Believing the invention to be destitute of novelty, he directed the jury that, in point of law, the invention under the second patent was not patentable. The jury gave their verdict in favour of the defendant, but the verdict was set aside, and a new trial granted on the ground of misdirection. The judge, it will have been observed, treated the conclusion to be drawn from the evidence as a matter of law; whereas he ought to have left it to the jury to say whether fresh and spent madder had different properties, chemical or otherwise, or whether they were the same thing, with the difference only that part of the colouring matter had been already extracted. If the properties of the two substances were different, the invention was a new manufacture; but if the two things were the same, except that one was more charged with colouring matter than the other, in that case the invention claimed would simply have been the application of a process already known, producing a known result. It was for the jury to say, upon the evidence, whether the invention was a new manufacture or not. (Steiner v. Heald, 6 Exch. Rep. 607.)

The question of infringement is one of mixed law and fact. There may well be a case' (said Lord Campbell, in De la Rue v. Dickinson, 7 E. & B. 738) where the judge may and ought to take upon himself to say that the plaintiff has offered no evidence to be left to the jury to prove infringement, as if there be a patent for a chemical composition, and the evidence was that the defendant had constructed and used a machine for combing wool. But if the evidence has a tendency to show that the defendant has used substantially the same means to obtain the same result as specified by the plaintiff, and scientific witnesses have sworn that the defendant actually has used such means, the question becomes one of fact or of fact mixed

with law, which the judge is bound to submit to the jury.' In deciding the question of infringement there is (said Lord Wensleydale, in Seed v. Higgins, 8 H. L. Cas. 550) ‘a question of fact wholly for the jury--viz. what the defendants have done; and if scientific evidence is necessary fully to elucidate the case on either side, it is no doubt admissible; and in determining the question of infringement the judge must apply what the jury find to be true.'

It is a question for the judge whether, on proof of certain acts having been done by a defendant, the plaintiff has any case to go to the jury. Per Lord Chelmsford, in Seed v. Higgins (8 H. L. C. 550).

Damages: Account of Profits.-It is now settled that the plaintiff in a patent action cannot have both damages and an account of profits, but must elect between the two which he will adopt. (Neilson v. Betts, L. R. 5 H. L. 1.)

In estimating the amount of damages sustained by a plaintiff in respect of an infringement of his patent, the Court adopts a form of inquiry different from that which it employs in the analogous case of an imitation of a plaintiff's trade-mark. In the latter instance the Court will not assume in the absence of evidence that the plaintiff would have sold all the articles which the defendant has wrongfully sold. (The Leather Cloth Co. v. Hirschfeld, L. R. 1 Eq. 299.) But every sale without licence of a patent article must be a damage to the patentee, and therefore the inquiry in a patent case will extend to the sale by the defendant of any articles made by him since the infringement was commenced. (Davenport v. Rylands, 1 L. R. Eq. 308.) The inquiry will extend to the sales by the defendant within six years before the commencement of the proceedings (Davenport v. Rylands, L. R. 1 Eq. 302; Crossley v. Derby Gas Light Co., 1 W. P. C. 119); but if the plaintiff be an assignee of the patent the amount will only be taken from the date of the registration of the assignment to him. (Elwood v. Christy, 5 N. R. 312.) And in stating such an account the defendant must file an affidavit, stating the number of the patented articles made by him since the date of the patent,

and the names and addresses of the purchasers to whom the same have been sold (Murray v. Clayton, L. R. 15 Eq. 115; American Braided Wire Co. v. Thomson, No. 2, 5 R. P. C. 375), and the account may be taken notwithstanding the pendency of an appeal. (Saxby v. Easterbrook, L. R. 7 Ex. 207.)

Where separate proceedings have been taken against the manufacturer and user of the patented article the plaintiff may have an account of profits against the manufacturer, and also damages against the user (Penn v. Bibby, L. R. 3 Eq. 308; United Telephone Co. v. Walker, 4 R. P. C. 67), and he cannot be compelled to accept the same royalty from a litigant as he receives from others (ibid.); but a patentee being himself a manufacturer of the patented article, and having been in the habit of licensing the use of his invention on payment of a fixed royalty, is not entitled to claim as against an infringer a manufacturing profit in addition to his ordinary royalty (Penn v. Jack, L. R. 5 Eq. 81); and where such a patentee had in some instances received from users (not being the manufacturers of the patented article) his ordinary royalty, it was held that in every such case no further royalty was payable by the manufacturer (ibid.).

Where there has been unnecessary delay in filing the bill an account of profits before the filing of the bill will not be ordered. (Harrison v. Taylor, 11 Jur. N. s. 408; Beard v. Turner, 13 L. T. N. s. 746; Ford v. Foster, L. R. 7 Ch. 616; Crossley v. Derby Gas Light Company, 1 Web. P. C. 120.)

In taking the account of profits made by the use of his invention, a successful plaintiff is entitled to know for comparison the profits made by the defendants in their business prior to the date at which they first used the plaintiff's invention. (Siddell v. Vickers, 6 R. P. C. 464.)

The material question for consideration in estimating damages is the actual loss entailed on the patentee, not the profit made by the infringer. (United Horsenail Company v. Stewart, L. R. 13 App. Ca. 413.) And in that case