assistance of persons answering this description. (See C. J. Tindal's remarks in Walton v. Potter, 1 W. P. C. 595.)

It sometimes happens that, between the grant of letters patent and the filing of the specification, the patentee discovers that his original invention is capable of material improvement. The intervening period is allowed the patentee for the very purpose of perfecting his invention; and therefore, if he fails to communicate to the public the best information he possesses at the time of filing the specification, it will be void. In Crossley v. Beverley (1 W. P. C. 117), it was objected that the patentee had added something to the invention between these two periods; but, said Bayley, J., “ I think that if between taking out the patent and filing the specification the inventor makes discoveries which will enable it better to effectuate the thing for which the patent was obtained, not only is he at liberty to introduce them into his patent, but it is his bounden duty so to do, and it is not sufficient for him to communicate to the public the knowledge he has obtained before the specification." It must, however, be understood that the additions must strictly relate to the invention as it stood at the time of the grant of the patent. It is not competent for a patentee to introduce new heads into the specification, or in any way to extend the subject-matter of the invention (Crossley v. Potter, Macr. P. C. 240; Bailey v. Roberton, L. R. 3 App. Ca. 1055). And assignees of a patent should know that the specification itself is not conclusive evidence of the invention; for the inventor may be called to state in Court what his invention really was, and he may show that it was something different from that specified. (Bateman v. Gray, Macr. P. C. 111; Crossley v. Potter, Macr. P. C.

CLAIMS.

It is usual for a patentee to insert at the close of his specification certain clauses, which are known as "claims." The insertion of these claims is not insisted on by the law, but they offer an opportunity for the patentee to define his invention, and to set forth in a brief form what he considers the pith and essence of it. "The real object of what is called a claim" (said James, L. J., in Plimpton v. Spiller, L. R. 6 Ch. D.412,426) " is not to claim anything which is not mentioned by the specification, but to disclaim something. A man who has invented something gives in detail the whole of the machine in his specification. In doing that he is of necessity very frequently obliged to give details of things which are perfectly well known and in common use; he describes new combinations of old things to produce a new result or something of that kind. Therefore, having described his invention and the mode of carrying that invention into effect, by way of security he says: 'But take notice I do not claim the whole of that machine; I do not claim the whole of that modus operandi, but that which is new, and that which I claim is that which I am now about to state. That really is the legitimate object of a claim, and you must always construe a claim with reference to the whole context of a specification."

Great care should be taken in preparing this epitomized definition, so as not to include things that are beyond the boundary of the invention, nor on the other hand to restrict the inventor's rights within too narrow limits. Where a specification clearly and distinctly claims a combination alone, a patentee is not bound to disclaim expressly everything he has described, because in such a case it will be held that everything which is not claimed is impliedly disclaimed (Harrison v. Anderston Foundry Company, L. R.

1 App. Ca. 574); and, therefore, where a patentee claims in his specification only an entire combination, he will be considered not to have claimed any of the minor combinations. A combination of three parts is a different thing from a combination of two of them; and if a patentee desires to secure the minor combination he must distinctly claim it (Clark v. Adie, L. R. 10 Ch. 667, affirmed on appeal, L. R. 2 App. Cas. 315). It is the patentee's duty to give distinct and definite information to the public somewhere in his specification as to the invention or inventions which he supposes his patent covers, and which he considers to be his own exclusive property. If he does this in the form of a claim, he must keep in mind what has just been stated, that everything which is not claimed is impliedly disclaimed. "With the view of getting this (information) into a narrow compass" " (said Jessel, M. R., in Hinks v. Safety Lighting Co., 4 Ch. D. 607)," it has long been the practice to insert in specifications the distinct claim of what is said to be comprised in the patent; meaning that nothing else is comprised, that everything else is thrown open to the public; or, to put it into other words, if a man has described in his specification a dozen new inventions of the most useful character, but has chosen to confine his claim to one, he has given to the public the other eleven." When the claims refer to the invention in very short terms, and introduce the words, "as hereinbefore described," this will render an examination of the previous description necessary, in order to ascertain what the invention really is.

In drawing the claims in a specification which refers to a machine or apparatus, consisting of many old and new parts, it is desirable to introduce a general claim to the entire machine as a combination, and then separate claims to the new minor combinations

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and to the new parts. An observance of this rule will be attended with useful results, in case there should arise any necessity to disclaim part of the invention.

In Kay v. Marshall (2 W. P. C. 39), Cottenham, L. C., said: "The claim is not intended to aid the description, but to ascertain the extent of what is claimed as new. It is not to be looked to as the means of making a machine according to the patentee's improvements. If, therefore, the specification containing the description be sufficiently precise, it cannot be of any consequence that expressions are used in the claim which would be too general if they proposed to be part of the description." See also Lister v. Leather (3 Jur. N. s. 811; S. C. in error, 8 E. & B. 1004). And if a claim to a material can be substantiated, the description in another claim of a particular user of that material comprehended in the general user claimed, will not vitiate the patent. (Neilson v. Betts, L. R. 5 H. L. 21; and see also Plimpton v. Spiller, L. R. 6 Ch. D. 412.)

On the other hand, where the description in a specification was in the first instance too general, but the inventor afterwards in describing his invention referred to certain figures in drawings annexed to the specification, and the claim was for the invention described with reference to those figures, the specification was held sufficient (Daw v. Eley, 14 W. R. 126, and on another hearing, L. R. 3 Eq. 497). See also Russell v. Cowley (1 W. P. C. 465), Thomas v. Welch, L. R. 1 C. P. 192.

All the claiming clauses may be struck out of the specification by disclaimer, if there remains sufficient in the specification to show distinctly what the invention is. (Thomas v. Welch, L. R. 1 C. P. 192.)

An important decision with respect to the extent of a patentee's claims was that delivered by Lord

Hatherley, L. C., in the case of Arnold v. Bradbury, L. R. 6 Ch. 706. A patent was obtained for an improved ruffle and sewing machine. The specification stated that the invention related to an improved frill or gathered fabric, and to the machinery for making the same; that the apparatus used in producing the article consisted of a peculiar mechanism for gathering and feeding one of the fabrics operated on, which mechanism was used in combination with a sewing machine, the latter being modified to receive it. The gathers in a fabric were fed into the machine by mechanism without being scratched by a pointed instrument as when formed by hand. A description of the mechanism was then given. Drawings figured the mechanism, and one of them showed a portion of a sewing machine to illustrate its operation. The claims were for-(1) The production by machinery of gathered work when it was simultaneously attached to a plain fabric by stitches; (2) the production by machinery of gathered work when it was simply gathered and secured on itself by stitches; and (3) the combination of mechanism for gathering with the mechanism of a sewing machine for the two purposes above mentioned. It was contended by the defendants, who admitted the infringement, that the patent was void, because the two first claims were too wide and general, inasmuch as they claimed the production of gathered work by any kind of machinery. Lord Hatherley, however, said that a claim must be very large and vague indeed to justify any Court in saying that it is impossible to sustain a patent based upon it. He read the first claim as one for the production by machinery of that which had not been done by machinery before, viz. an improved frill. The inventor had stated in what the improvement consisted, and he described the machinery by which it was produced,