§ 260. But although it is necessary that a specification should clearly and fully describe the invention, and should give the best process, materials, and methods known to the inventor, yet it is not necessary for the patentee to describe the mode of making everything which he uses, or detail known processes, or explain the terms appropriate to the particular art, or science, or branch of industry to which his invention belongs. The specification is, as we have seen, addressed to persons acquainted with the nature of the business; some technical knowledge is presumed on the part of those who will undertake, after the patent is expired, to carry out the invention; and such persons are to be called as witnesses to explain the language to the jury, while the patent is in force, and to show that it is capable of being understood by those to whom it is addressed. Accordingly it has been said, that a ing to the plaintiff's scale, I would say it is of no use at all for sheathing. It is perfectly useless in more respects than one. It does not corrode enough, it is too hard, too brittle, it would roll at a red heat and at a cold heat.' Then he goes to some others, 47 of zinc, 53 of copper, this would corrode less than the last mentioned, and be more brittle; 48 zinc and 52 copper still more, quite useless for sheathing. I do not think it could be put on a ship on account of its being brittle.' What he says of all this is that it would roll at a red heat. Now the question is, whether, looking at this specification, more is meant or intended by the expression in it, when the patentee is giving these quantities, than that it shall be a metal which will roll at a red heat. This is what he (the patentee) says: 'I melt them together in the usual manner in any proportions between 50 per cent copper to 50 per cent zinc, and 63 per cent copper to 37 per cent zinc, both of which extremes and all intermediate proportions' - he does not say will oxidize sufficiently, or will make sheathing for a ship, but -'will roll at a red heat'; and then he goes on to say, as to the other quality which this is to possess, but as too large a proportion of copper increases the difficulty of working the metal, and too large a proportion of zinc renders the metal too hard when cold, and not sufficiently liable to oxidation to effect in the best manner the intended purpose, I prefer the alloy to consist of about 60 per cent of copper to 40 per cent of zinc.'

"Therefore, understanding the specification in that way, the question (the only question of fact that you can determine upon this) is, whether this account, which his own witness has given of it, has falsified the statement in the specification. If that statement had been distinctly that the lower mixture of the lower compound, the extreme, would have been sufficient for the sheathing of ships, both in respect of oxidation and of rolling hot, I should have thought the specification bad and avoided the patent. But you must say for yourselves whether you are satisfied that all that was described here was, that it would roll at a red heat and at the intermediate states; whether, in point of fact, it would roll at a red heat."

1 Per Lord Abinger, C. B., in Neilson v. Harford, Webs. Pat. Cas. 341. See also Derosne v. Fairie, Ibid. 154, 167.

specification containing scientific terms, which are not understood, except by persons acquainted with the nature of the business, is not bad because an ordinary person does not understand it, provided a scientific person does; but a specification using common language, and stating that by which a common man may be misled, though a scientific man would not, when it does not profess to use scientific terms, and an ordinary man is misled by it, would not be good. And it has been held that if a specification contain an untrue statement in a material circumstance, of such a nature that, if literally acted upon by a competent workman, it would mislead him, and cause the experiment to fail, the specification is therefore bad, and the patent invalidated, although the jury, on the trial of an action for the infringement of the patent, find that a competent workman, acquainted with the subject, would not be misled by the error, but would correct it in practice. This rule, however, must not, we apprehend, be applied too rigorously. Where the specification contains the description of a long and complicated process, consisting of several operations following one another in regular order, and the description as a whole is clear and sufficient, the court will not pronounce it invalid because of a slight obscurity of language in describing one of the operations, especially where such obscurity is rather grammatical than real, and would not seriously mislead a competent workman.3 1 Per Lord Abinger, C. B., in Neilson v. Harford, Webs. Pat. Cas. 341. See also Derosne v. Fairie, Ibid. 154, 167.

Neilson v. Harford, 8 M. & W. 806; s. c. Webs. Pat. Cas. 328.

* Beard v. Egerton, 8 Mann. Gr. & Scott, 165, overruling s. c. 2 Carr. & Kirw. 667. "Applying the same principle of construction to the specification before us, we think it is free from any such mistake or obscurity as would mislead a person of fair intelligence. The specification states that the process is divided into five operations. The first consists in polishing and cleaning the silver surface of the plate, in order to properly prepare or qualify it for receiving the sensitive layer or coating upon which the action of the light traces the design. The second operation is, the applying that sensitive layer or coating to the surface. The third, in submitting in the camera obscura the prepared surface or plate to the action of the light, so that it may receive the images. The fourth, in bringing out or making appear the image, picture, or representation which is not visible when the plate is first taken out of the camera obscura. The fifth and last operation is that of removing the sensitive layer, &c.' It then gives a description of the first operation, preparing the silver surface of the plate; the concluding part of which directs that nitric acid dissolved in water is to be applied three different times, care being taken to sprinkle, each time, the plate with powder, and rub it dry and very lightly with clean cotton; and this concludes the description of the

§ 261. The specification need not describe that which is within the ordinary knowledge of any workman who would be employed to put up the apparatus; as, a condenser in constructing a gas apparatus. So, too, a deviation from the precise dimensions shown by the specification and model, so as to make different parts work together, is within the knowledge of any workman.2 But if first operation, viz., the preparing the silver surface of the plate, when it is intended for immediate use; and to this part of the specification no objection was or could be made. But then some further information is given in respect to the preparation of the plate, in these words: When the plate is not intended for immediate use or operation, the acid may be used only twice upon its surface, after being exposed to heat. The first part of the operation, that is, the preparation as far as the second application of the acid, may be done at any time; this will allow of a number of plates being kept prepared up to the last slight operation. It is, however, considered indispensable, that just before the moment of using the plates in the camera, or the reproducing the design, to put at least once more some acid on the plate, and to rub it lightly with pounce, as before stated; finally, the plate must be cleaned with cotton from all pounce-dust which may be on the surface or its edges.' Upon this part of the specification it was contended that the direction to apply acid just before the moment of using plates in the camera (which is the third operation), was a direction to use it after the second operation, viz., the coating the plate with iodine; and that using the acid at that period would entirely spoil the whole process. But it must be remembered that the passage in question is part of the direction given for performing the first operation, viz., preparing the plate to receive the iodine. It is to be observed when the plate is not intended to be used immediately, and where it has previously been partially but not entirely prepared for the iodine, this last application of acid is still to precede the second operation. The whole passage may be considered as in a parenthesis, and the expression 'just before the moment of using the plate in the camera' is put in opposition to the time of partially preparing the plate; after which it is supposed to have been laid by for future use. That this is the real meaning of the passage is further manifested by what follows in a subsequent part of the printed specification: After this second operation, viz., application of the iodine, the plate is to be passed to the third operation, or that of the camera obscura. Wherever it is possible, the one operation should immediately follow the other.' It is plain, therefore, that the patentee did not intend any separate operation to intervene between the application of iodine and the introduction of the plate into the camera obscura. The last application of acid, therefore, must have been intended to precede the second operation.

"This, we think, is the fair construction of the language of the specification. And although there may be at first sight some appearance of obscurity in it, we think that it is cleared away by a consideration of the whole, and that it is sufficiently plain to be understood by an operator of fair intelligence." Wilde, C. J. Crossley v. Beverley, Webs. Pat. Cas. 110, note.

1

'Morgan v. Seaward, Webs. Pat. Cas. 176. In this case, Alderson, B., said to the jury: "In the case of the steam engine, there was put in, on the part of the

the practical application of the invention involves a particular kind of knowledge on the part of a workman, requiring him to do that which a person of ordinary engineering skill ought to know how to do, it must at least suggest to him that that thing is to be done, if it does not specifically point out the mode of doing it. In like manner it is not necessary, in the description of a machine, to state of what material every part should be made, where the principle of operation and the effect are the same, whether the parts be made of one material or another; 2 but if a particular material be essential to the successful operation of the machine, as the patentee uses it, he must direct the use of that material.

Thus where the invention was the formation of grinding chamdefendants, a model made, as it was said, according to the specification, which model would not work. The model was a copy of the drawing, and would not work, because one part happened to be a little too small, whereas if it had been a little larger, it would have worked. Now, a workman of ordinary skill, when told to put two things together, so that they should move, would, of course, by the ordinary knowledge and skill he possesses, make them of sufficient size to move. There he would have to bring to his assistance his knowledge that the size of the parts is material to the working of the machine. That is within the ordinary knowledge of every workman. He says: 'I see this will not work, because it is too small,' and then he makes it a little larger, and finds it will work; what is required is, that the specification should be such as to enable a workman of ordinary skill to make the machine; with respect to that, therefore, I do not apprehend you will feel much difficulty."

1 In the case last cited, the same learned judge further instructed the jury as follows: "Mr. George Cottam says: 'It is a common problem to find a centre from three given points, and a person of ordinary engineering skill ought to be able to do that.' The question is, whether it ought not to be suggested to him by the specification, that that is the problem to be solved. Then Mr. Curtis says: 'I have made wheels on this plan.' You see he made the two wheels which were sent to the Venice and Trieste Company, but those were made under the direction of Mr. Galloway, the inventor. Now, it somewhat detracts from the weight due to his testimony, not as to respectability, but as to the value of his evidence to you, that he had received the verbal instructions of Mr. Galloway. It may be, that he could do it because of his practice under Mr. Galloway; and it must be recollected that people in other places would not have that advantage. He says, he would not have any difficulty in doing it; and he says: 'I should not consider my foreman a competent workman unless he were able to make the wheel from the specification and drawings.' He says: 'I could alter the angle by altering the cranks.' The question is not, whether he could do that, but whether he could alter the angle to a particular angle by altering the cranks in a particular way, that is, whether, having the angle given to him, he could make the alteration that was desired."

2 Brooks v. Bicknell, 3 McLean's R. 250, 261.

bers by the combination of movable conical rings with stationary cylinders, and the particular description in the specification showed a mill with three grinding chambers, but the claim was to the combination of stationary cylinders with one or more movable conical rings, so that both cylinders and rings might be multiplied to any extent, or the mill limited to two cylinders and one ring, it was ruled by the court that the description was sufficient to enable a mechanic of ordinary skill to make a mill with more chambers than three.1

§ 262. In the case of machinery, the statute directs the patentee to accompany his specification with "a drawing or drawings, and written references, where the nature of the case admits of drawings." The object of annexing drawings is both to distinguish the thing patented from other things known before, and to explain the mode of constructing the subject of the patent. It has been settled, that the drawings constitute a part of the specification, when annexed thereto, and may be used to explain or help out the otherwise imperfect description in the specification. So that it is not necessary that the description should be wholly in writing, but it may be partly in writing and partly in drawing; and if, by a comparison of the words and the drawings, the one will explain the other sufficiently to enable a skilful mechanic to perform the work, and to show what is the invention claimed, the specification will be sufficient. And it has been held, that in order to make a drawing when annexed to or accompanying a specification, part of the specification, so that the written description may be read by it, it is not necessary that the written description should contain references to the drawing; that the direction in the statute, to annex "drawings and written references," means that where references from the writing to the drawing are necessary to the understanding of the machine or improvement, they are to be made; but that the description of many machines or improvements, when accompanied by a drawing, may be perfectly understood without references in the description itself.3

1 Wilbur v. Beecher, 2 Blatch. 132.

Earle v. Sawyer, 4 Mas. 1, 9; Bloxam v. Elsee, 1 Car. & P. 558; Brunton v. Hawkes; 4 B. & Ald. 540.

'Brooks v. Bicknell, 3 McLean's R. 250, 261; Washburn v. Gould, 3 Story's R. 122, 133.