the mistake committed by the patentee may be such as would at once be observed by an ordinary workman. (Simpson v. Holliday, 13 W. R. 577.)

It would seem from Crossley v. Beverley (3 C. & P. 515), that in construing a specification, the state of the particular manufacture at the date of the patent must be kept in view. In this case, in describing a gas apparatus, no directions were given as to a condenser; but since a workman capable of constructing a gas apparatus knew that he would have to put it in, the specification was held sufficient. The patent in Russell v. Cowley (1 W. P. C. 459) was for a method of manufacturing iron tubes without the use of a mandrel. The specification gave no directions as to leaving out the mandrel; but it was held that an intelligent workman would sufficiently understand, from the purport of the specification, that a mandrel was not to be used. So, in Beard v. Egerton (8 C. B. R. 165), it was held that a competent operator would perceive, on perusing the whole specification, that it would not be necessary to interpose an operation at a certain stage in the process of daguerreotyping.

Again, in Otto v. Linford (46 L. T. N. s. 35) the specification under a patent for gas motor engines did not state the proportion of atmospheric air to be let into the chamber where the inflammable gas was fired with the view of producing a gradual in place of an explosive ignition. Nevertheless it was held that as exact proportions were not required to be mentioned, and as there was enough information in the specification to enable a maker of machinery to construct a working engine without exercising his inventive powers, the specification was sufficient.

It sometimes occurs that the drawing attached to the specification is erroneous in some particular, so that if an attempt were made to construct, the machine by

the drawing it could not be done, or if made it would not work. If, however, the text has correctly described the construction, or if the error is of a kind which an ordinary workman would easily perceive and rectify, requiring not experiments, but merely regulation, then the error in the figure will be disregarded, and will not be held to vitiate the patent. (Otto v. Linford, 46 L. T. N. s. 35.)

How combinations should be treated.

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The patentee ought to state whether his invention consists of the useful application of a principle, or whether it lies in a particular form or arrangement or combination of parts. It has been already stated (Chap. II.) that a number of old and well-known things, such as implements, machines, or parts of machines, may be combined so as to form a new and useful instrument or machine; and a patent obtained for such combination will be valid, care being taken that the specification does not claim the old parts as well as the novel combination. If,' said Gibbs, C. J., to the jury, on trying the case of Bovill v. Moore, a patentee has only invented an improvement, then his specification by which he claims the whole will be bad. If, on the other hand, he has invented an engine which consists of a perfectly new combination of parts, although all the parts were used before, yet he will be entitled to support his patent for a new machine. . . . If a combination of a certain number of these parts existed up to a given point before the date of his patent, and if the patentee's invention sprung from that point, and added other combinations to it, then his specification, stating the whole machine as his invention, is bad.' (Dav. P. C. 404.)

If all the parts of an invention, taken separately, are old, the patent being obtained only for a novel

combination of them, the patentee, in preparing his specification for such an invention, must take care to limit his claim to the new combination. (Lister v. Leather, 3 Jur. N. s. 811; S. C. in error, 8 E. & B. 1004; Seed v. Higgins, 8 H. L. C. 550; Potter v. Parr, 2 B. & S. 259.) The case of Kay v. Marshall (2 W. P. C. 71) deserves attention with reference to this rule. The inventions claimed in the specification were two: first, certain new machinery for macerating flax; and secondly, improved machinery for spinning flax. The first invention would very well have supported the patent separately considered. It was that part of the specification which described the second invention that broke down. The so-called improved machinery, considered in itself, and apart from its application, was shown to be wanting in novelty, and hence the patent fell to the ground. Had Kay, instead of claiming the invention of improved machinery, claimed only the invention of a combination of a known process of wetting flax, with the use of known machinery for spinning the same, certain parts of such machinery being at a given distance from each other, the patent would, doubtless, have been held good. The combination was new, although the process and the machinery were old. The invention was one of great value, and if the specification had been rightly framed, the patentee might have had the benefit of it, without suffering the anxiety and expense of litigation in the common law courts, the Court of Chancery, and the House of Lords.

The case of Tetley v. Easton (Macr. P. C. 48) went three times before a jury, and on two of the occasions the plaintiff failed by inattention to this rule. His patent was for improvements in machinery for raising and impelling water. The specification described a great number of mechanical contrivances for effecting

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the object in view, and concluded by claiming, as the patentee's invention, the several contrivances, both when all used in combination, and when used severally.' It was shown, on the trial of the first action for an infringement, that several of these contrivances were old; and with regard to one in particular, which the defendants were charged with infringing, that a person named Hales had previously procured a patent for something substantially the same. The jury thereupon found a verdict for the defendants upon issues which raised the question of the novelty of the plaintiff's invention. Subsequently to this trial the plaintiff entered a disclaimer as to several parts of his specification, and brought another action against the same defendants. The jury again returned a verdict for the defendants. A rule to set aside the verdict, and for a new trial, having been obtained, the legal questions came on for argument before the full court. It appeared that the amended specification described a centrifugal pump, composed of a hollow wheel, revolving within a case furnished with pipes for conveying the water. This wheel was not stated to be old, nor was it disclaimed. The specification claimed generally the machinery for raising and impelling water. It also claimed the application of the inventions before mentioned, both when all used in combination, and when used severally.' It was held that the hollow revolving wheel was thereby claimed, and as this was an old invention, the specification was bad. By a second disclaimer the patentee's claims were reduced to the single one of the means of increasing the action of the machine by causing the liquid to enter the wheel at both sides;' and he then brought a third action for the infringement of his patent. Unfortunately it was shown that previous inventions had embraced a contrivance for the admission of the water on

both sides of the wheel; and Mr. Justice Willes directed the jury to find for the defendant, for the reason that although the wheel had been previously combined with apparatus which made the combination useless, yet that the contrivance in question had been made public property, and could not of itself be made the subject of a patent. The court, on the argument. of a rule for a new trial on the ground of misdirection, said that the use of a wheel known before, in a manner known before, could not be deemed an invention capable of sustaining a patent, and held that the judge was right. (2 C. B. n. s. 706.)

The specification under a patent for an improved turning-table for railway purposes, after describing the machinery, claimed as new the improved turningtable as herein before described.' Now it appeared, on the trial of an action for an infringement, that no part of the machinery was new except certain suspending rods. It was held that the specification claimed the parts as well as the combination forming the turning-table, and that it was defective by reason of its not distinguishing what was old from what was new. 6 Every patentee,' said Jervis, C. J., must, in his specification, describe the nature of his invention in such a way as that those who read it with common, ordinary understanding, and fairly read it, may see and understand what is new and what is old.' (Holmes v. London and N. W. Railway Co., Macr. P. C. 26.)

In the case of Foxwell v. Bostock (4 De G. J. and S. 298) Lord Westbury, C., laid down the rule to be that in a patent for an improved arrangement or new combination of machinery, the specification must describe the improvement and define the novelty, otherwise and in a more specific form than by the general description of the entire machine. On both principle and authority it is most necessary that the specification