MAY 17. COUNTY OF FOND DU LAO.
by which to determine unerringly, in every case, what will amount to substantial identity. The jury. guided by general principles, mllst determine each case upon its own circumstances. If, however, the invention of the patentee be a machine, or an improvement on a machine, it will be infringed by a machine which incorporates in its structure and operation the substance of the invention; that is, by an arrangement of its mechanism which performs the same service, or produces the same effect, in the same, or substantially the same way. The question is whether the given effect is produced substantially by the same mode of operation, and the same combination of powers and devices in both machines. Mere colorable or evasive differences cannot defeat the right of the original inventor. The inquiry, therefore, should be whether the defendant's device is, in substance and effect, a colorable evasion of the plaintiff's contrivance, or whether it is really a new and substantially different thing. If the defendants have taken the same general plan, and applied it for the same purpose, and produced the same effect, in substantially the same mode, although they have varied the form or construc,tion merely, it will still be, substantially, in contemplation of the patent law, the same thing; otherwise it will not. Whether or not one machine is an infringement of another, therefore, does not necessarily depend upon whether the mechanical constructions are different; but the question is whether, whatever be the mechanical construction, the latter machine contains the means Qr combination found in the previous machine; whether, taking the structure as you find it, you see the new idea completely embodied in it. * * * If the defendants have only varied their combination by employing well-known mechanical substitutes for some one or more material elements or parts of the plaintiff's combination, then there is an infringement; for a mere known mechanical substitute for a thing, for the purpose of determining the question in issue, must be regarded as the thing itself. * * * When, in mechanics, one device does a particular thing, or accomplishes a part,icular result, every other device known and used in mechanics, which skillful and experienced workmen know will produce the same result,ordo the same particular thing, is a known mechanical substitute for the first device mentioned, for doing the same thing or accomplishing the same result, although the first device may never have been detached from its work, and the second one put in its place. It is sufficient to constitute known mechanical substitutes that when a skillful mechanic sees one device doing a particular thing, that he knows the other devices, whose uses he is acquainted with, will do the same thing."
Now, within these definitions, does the structure used by the defendant infringe the May device? In their general scope and object they seem to be quite alike, and are evidently intended to secure the same result. Do they differ essentially in their organization or mode of operation? The one is evidently equivalent to the other, as producing the same result. But in this sense it is not material to consider the subject. The question is whether the defendant has used substantially the same means, or, mechanically speaking, equivalent means, to accomplish the same result. If it has, it is an infringer; otherwise not; and whether it has or not is a question for the jury to determine. As we have seen, a mechanical equivalent, as generally understood, is where one may be adopted instead of the other, by a skilled mechanic, accustomed to machinery, with a competent knowledge of mechanical powers. If such a man, seeing a new machine" and baving a full description of the thing invented, can, by examin-
ing it with care, see that the required thing can be done in a different mode, and it is done in that different mode by the knowledge which he has of his business, he has not produced a new invention, nor one substantially differing from the original. But if the inventive faculties are exercised to produce the change, then he has a right to the benefits of whatever he thus invents. There must be invention involved in the change, and not the mere skill of the workman, to avoid the consequences of an infringement. The question here is, does the structure used by the defendant substantially embody May's mode of opera.tion, and thereby obtain the same results as were reached by his invention? It is not necessary that the result should be precisely the same in degree, but it must be the same in kind. For instance, shutting one door instead of two is a difference in degree, but not in kind; the same function is performed. Now, keeping in mind that the May invention consists of certain mechanical means which enable the jailer, from the moment he enters the outer door, to control the prisoners, by fastening the corridor doors while separated from them, the question is, do the means employed by the defendant in its jail infringe them? Has the defendant used the plaintiff's invention, or something substantially like it? Do the structures operate upon the same principle? If there are differences, are they or not mere differences in form, producing the same result? The plaintiff's invention secured to the inventor not only the particular means described in the patent, but all other mechanical contrivances which are equivalents. When these me· chanical arrangements are thus compared and analyzed, if differences be found, it is for you to determine whether these differences are substantial, or are only formal and evasive, arising from employing in the defendant's jail, in the place of those specific parts or devices of the May combination, other known mechanical substitutes therefor. If substantial, then there is no infringement; but if merely formal or evasive, and not substantial, there is an infringement. The testimony of the expert which has been introduced you are to consider like any other evidence. You are to try it by the same tests that you apply to the evidence of other witnesses, and give it just such credit and weight as you deem it entitled to from all the circumstances, and no more. You have the models before you, and these, I think, are readily comprehended. 1'he undisputed evidence shows, I think, a fixed royalty of $50 for each cell, at which the plaintiff's device, or the right to use it, was sold by the patentee in his lifetime. In such a case it is the ruling of the courts that such royalty constitutes the proper measure of damages. If, therefore, you find the plaintiff entitled to recover, you will allow her damages at the sum of $50 for each cell in the Fond du Lac jail on which the invention was used priOlO to October 4, 1880, and subsequent to October 4. 1873. If there were 34 cells upon which it was used, the total amount would be $1,700; and if you find for the plaintiff, you may
KEARNEY fl. I,EHIGH VAL. R. CO.
allow to her interest upon the gross sum at 7 per cent. from September 29, 1885. I have drawn forms of verdict, gentlemen, which I will allow you to take; and if you find for the plaintiff, we will ssk you to state which of these claims you find are infringed. You understand that if you find all these three claims, or either of them, infringed, then your verdict must be for the plaintiff. If you find that neither of the claims is infringed, your verdict will be for the defendant; and the court will ask you to state in your verdict, in the manner indicated in the form of verdict which the court will hand to you, what you find as to infringement of the claims. Verdict finding infringement of each of the three claims in sui··
KEARNEY and another v.
VAL. R. Co.1
(Circuit Oourt, D. New Jer8ey. June 3, 188!t)
PATENTS FOR INvBNTIONS-INFRINGEMENT-PARTmS-PLEADING-EsTOPPEL,
To support a plea in abatement for non-joinder of parties in a suit for infringement of a patent,. defendant offered in evidence a written certificate given by plaintiffs to a third person, and reciting that such person had "onethird equal interest with ourselves in the said patent. to Defendant urged plaintiffs were estopped from showing by parol that the writing did not state the agreement and intention of the parties. Held, that this was not a case for the invocation of the doctrine of estoppel.
The bill of complaint in this case was illed March 15, 1883, by plaintiffs, claiming to be the sale owners of the patent sued on and all rights under it. On May 10th following, defendant procured an assignment of the patent and a release of infringement claims from one who claimed an interest. Held, ,that defendant was a purchaser with notice, and was subject to all the equities that could be invoked against its assignor. A certificate ?iven by patentees, which recited that the party to whom it. was given had 'one-thIrd equal interest with ourselves in the said patent,"
ing that it was not intended by the parties giving it to operate as an assignment.
held not an assignment of the patent, or any part thereof; the evidence show-
Andrew McOallum, for complainants. Elwood G. Harris, for defendants.
NIXON, J. The bill of complaint was filed in this case by Francis Kearney and Mary F. 'l'ronson, as executrix of Luke F. Tronson, deceased, against the defendant corporation, for an injunction, and for the recovery of profits and damages for the alleged infringement of reissued letters patent No. 5,184, for new and useful "improvements in spark arresters for locomotives." The defendant has put in a plea in abatement of the suit, for the non-joinder of parties, alleging that·
C. Linthicum, Esq., afthe Chicago bar.