This case has been argued for the plaintiffs, as fully and as ingeniously as its merits wEl allow, upon the *923same principles and reasonings, which were pressed upon the court at the trial. If they have failed to convince the understanding of the court, it is because in some instances the premises, and in others, the conclusions are radically unsound and inadmissible. I pass over all the learned lecture, as to what constitutes matter of fact and what of law, and what are the relative rights of courts and juries as to matters of fact, because no novelty and no instruction can attach themselves to the discussion. The whole doctrine lies in the elements of the common law, undisputed and indisputable. As little do I think it necessary to discuss the question, what constitutes the identity or diversity of machines in the abstract; or to philosophize respecting the different mechanical powers. My humble knowledge does not permit me to venture on such difficult topics, and fortunately my duties as a judge do not require me to master them. I am content on these, as on other occasions, to learn from those, who can give the proper instruction, and then to apply it to the solution of such questions of law, as are fit to be entertained here. To be. sure, I must continue to believe, until better instructed, that the different mechanical powers are not one and the same power; and that a motion, which is communicated by a screw is not communicated in the same way as that by a lever, a wheel, a wedge, or a pulley. As to the opinion of skilful witnesses, whether the principles of two machines are the same, no person doubts, that it is competent evidence to be introduced into a patent cause. But care should be ta¿en to distinguish, what is meant by a principle. In the minds of some men, a principle means an elementary truth, or power; so that in the view of such men, all machines, which perform their appropriate functions by motion, in whatever way produced, are alike in principle, since motion is the element employed. No one, however, in the least acquainted with law, would for a moment contend, that a principle in this sense is the subject of a patent; and if it were otherwise, it would put an end to all patents for all machines, which employed motion, for this has been known as a principle, or elementary power, from the beginning of time. The true legal meaning of the principle of a machine, with reference to the patent act, is the peculiar structure or constituent parts of such machine. And in this view the question may be very properly asked, in cases of doubt or complexity, of skilful persons, whether the principles of two machines be the same or different. Now, the principles of two machines may be the same, although the form or proportions may be different. They may substantially employ the same power in the same way, though the external mechanism be apparently different. On the other hand, the principles of two machines may be very different, although their external structure may have great similarity in many respects. It would be exceedingly difficult to contend, that a machine, which raised water by a lever, was the same in principle with a machine, which raised it by a screw, a pulley, or a wedge, whatever in other respects might be the similarity of the apparatus. But, although the testimony of witnesses be admissible to prove the identity or diversity of machines in principle, yet, after all, it is but matter of opinion; and its weight must be judged of by .all the other circumstances of the case. It is infinitely more satisfactory to ascertain, if we can, the precise differences and agreements; and when these can be subjected to the eyes, they almost supersede all the evidence of mere opinion. In all my experience I can scarcely recollect a single instance, in which the general question, whether the principles of two machines were the same or different, has not produced from different witnesses, equally credible and equally intelligent, opposite answers. This could result only from the different meanings attached to the word, and from confounding its yarious senses. And this has been completely shown, when the same witnesses came to explain the precise agreements and differences, in which they have almost uniformly agreed. The case now before the court is a perfect proof in point. The witnesses differed as to the identity or diversity of the principles of the machines; but they were all agreed as to what were the precise differences and agreements in fact There seemed then nothing left for the jury to decide, but whether these differences were substantial or formal; if substantial, then the machines were not alike; if formal only, then they were alike. And the question, whether the principles were the same in both machines, was in reality, when all the facts were given, rather a matter of law, than of the opinion of mechanics; at least matter of law was necessarily mixed up with it, which mechanics could not be presumed to be acquainted with.
The opinion, however, which I shall express, will not turn in any material respect upon any facts controverted at the trial. I shall discuss the motion for a new trial, so far as facts are concerned, upon the admissions and statements, which the plaintiffs did not and could not deny. The doctrine of patents may truly be said to constitute the metaphysics of the law. The difficulty lies, not so much in the general principles, as in the minute and subtle distinctions, which occasionally arise in the application of those principles. I will endeavour, however, to lay down some general rules, which appear to me to embrace the whole merits of the present controversy, and then apply those rules more pointedly to the facts of this case.
In the first place, a joint patent may well be granted upon, a joint invention. There is no difficulty in supposing in point of fact, that a complicated invention may be the gradual result of the combined mental opera*924tions of two persons acting together, pari passu, in the invention. And if this be true, then as neither of them could justly claim to be the sole inventor in such a case, it must follow, that the invention is joint, and that they are jointly entitled to a patent. And so are the express words of the patent act,—Act Feb. 21, 1793, c. 11, § 1, [1 Stat. 318,] —which declares, that if any person or persons shall allege, that he or they have invented, &c. a- patent shall be granted to him or them for the invention. In the next place, a joint patent cannot be sustained upon a sole invention of either of the patentees; for the patent act gives no right to a patent, except to the inventor; and requires an oath from the party, who claims a patent, that he is the true inventor. In the next place, a joint patent for an invention is utterly inconsistent with -several patents for the same invention by the same patentees. For it is impossible, that any person can be, at the same time, the joint and sole inventor of the same invention. If, therefore, each of the joint patentees obtains a1 several patent for the same invention, as his own exclusive invention; and afterwards, without surrendering the first patent, they obtain a joint patent for the same as a joint invention, either the former sole patents are void, or the joint patent is void. For, besides the apparent inconsistency of the patents, if all could be sustained then' a recovery upon the joint patent would be no bar to a suit upon the several patents; and the parties might obtain a double recompense for the same infringement. There is an additional reason, which deserves great consideration; and that is, that if several and joint patents could be sustained by the same parties for the same invention, they might be successively taken out, so that the term of the exclusive right might be prolonged for a’ great length of time, instead of being limited to fourteen years. I am ’ therefore clearly of opinion, that a grant of a subsequent patent for an invention is an estoppel to the patentee to set up any prior grant for the same invention. which is inconsistent with the terms of the last grant. And I have very great doubts, whether, when a patent is once granted to any person for an invention, he can legally acquire any right under a subsequent patent for the same invention, unless his first patent be repealed for some original defect, so that it might truly be said to be a void patent.
In the next place if several patents are taken out by several patentees for a several invention, and the same patentees afterwards take out a joint patent for the same as a joint invention, the parties are not absolutely es-topped by the former patents from asserting the invention to be joint; but the former patents are very strong evidence against the joint invention. The reason of this doctrine is, not that estoppels are odious in the law, but that a party may innocently mistake, as to the extent of his own claims. And though a several and joint invention, by the same persons of the same thing, cannot exist in fact; yet a party may suppose, that he has invented, what in truth has been partly suggested by another mind.
In the present case, each of the plaintiffs (Barrett and Stearns) obtained, in the year 1809, a several patent for the present invention, as his sole invention; and the patent, on which this action is brought, is a joint patent granted in 1818. In this view, the doctrine already stated directly applies in the case. It is the same, as was stated to the jury at the trial, and on the most mature reflection, I adhere to it.
In the next place, a patent may be for a new combination of machines to produce certain effects; and this, whether the machines, constituting the combination, be new or old. But in such case, the patent being for the combination only, it is no infringement of the patent to use any of the machines separately, if the whole combination be not used; for in such a case the thing patented is not the separate machines, but the combination; and the statute gives no remedy, except for a violation of the thing patented. This was the doctrine of Mr. Justice Washington in his most able opinion in Evans v. Eaton, [Case No. 4,559;] and it has not been in the slightest degree shaken, in the supreme court. Evans v. Eaton, 3 Wheat. [16 U. S.] 454, 476, 506. I hesitate not one moment in adopting it, as established on solid foundations. It has indeed been said, that where there.is a patent for the whole of a machine, whoever imitates it, either in whole or in part, is subject to an action at the suit of the patentee. Bovill v. Moore, 2 Marsh. 211. But supposing this doctrine to be true in any case and under any qualifications, (which may well be. doubted,) it can apply, where the whole machine is entirely new, and cannot apply, where the patent is limited, by its very terms, to the combination of several machines.
Further. A patent under the general patent act, cannot embrace various distinct improvements or inventions; but in such case the party must take out separate patents. If the patentee has invented certain improved machines, which are capable of a distinct operation; and also has invented a combination of those machines to produce a connected result, the same patent cannot at once be for the combination and for each of the improved, machines; for the inventions are as distinct, as if the subjects were entirely different. A very significant doubt has been expressed on this subject by the supreme court; and I am persuaded, that the doubt can never be successfully removed. Evans v. Eaton, 3 Wheat. [16 U. S.] 454, 506.
Further. If a patent be for an improved machine, or for an improvement of a ma-
*925chine,—for I follow Mr. Justice Heath (Boulton v. Bull, 2 H. Bl. 463, 482) and the supreme court (Evans v. Eaton, 3 Wheat. [16 U. S.] 454) in thinking, that the meaning of the terms is substantially the same,—then the patent must state in what the improvement specifically consists; and it must be limited to such improvement. If, therefore, the terms be so obscure or doubtful that the court cannot say, what is the particular improvement which the patentee Claims, and to what it is limited, the patent is void for ambiguity. Macfarlane v. Price, 1 Starkie, 199. And if it covers more than this improvement, it is void for another reason, that it is broader than the invention.
Further. Where a combination of machinery already exists up to a certain point; and the patentee makes an addition or improvement to the machinery; he must confine his patent to the improvement; for if he takes a patent for the whole machine as improved, not distinguishing between the new and old, nor limiting his patent to the improvement, it is void, because, as so claimed, it is not his invention. Bovill v. Moore, 2 Marsh. 211.
Further. If an invention consist in a new combination of machinery, or in improvements upon an old machine to produce an old effect; the patent should be for the combined machinery, or improvements on the old machine, and not for a mere mode or device for producing such effects, detached from the machinery. This appears to have been the doctrine of all the judges in Boulton v. Bull, 2 H. Bl. 463, and was illustrated by several of the cases there put. And in a recent case, where a patent was obtained for “an improved mode of lighting cities,” it was neld, that it was not supported by a specification describing an improved street lamp; and that the patent ought to have been for an improved street lamp. Cochrane v. Smethurst, 1 Starkie, 205. So, where the patent was for “a new invented manufacture of lace, called French, otherwise ground lace,” and the specification went generally to the invention of mixing silk and cotton thread upon the frame; it being proved, that, prior to the patent, silk and cotton thread had been used together and intermixed upon the same frame, the court held the patent bad, since the plaintiff claimed the exclusive liberty of making lace, composed of silk and cotton thread mixed, and not of any particular mode of mixing it; and the evidence proved it had been mixed before. King v. Else, 11 Bast, 109, note. This doctrine may not be of as extensive consequence under our patent act, where the specification forms a part of the patent, and may control its generality, as it is in England, where the specification is separated from it. But it distinctly shows the necessity of an exact description so that the patent may conform to the invention.
Let us now apply these principles to the case at bar. The patent is “for a new and useful improvement, being a mode of dying and finishing all kinds of silk woven goods.” If these terms alone were to be considered as descriptive of the subject matter of the patent, it would be open to the objection in Cochrane v. Smethurst, 1 Starkie, 205, for the specification shows no other mode of dying and finishing silks, than by the use of an improved reel and an improved silk frame; and the patent ought to be for these improvements. But as the specifiaation forms a part of the patent, and controls the generality of the preceding terms; it is to be construed a patent for a mode of dying and finishing silk woven goods, by means of an improved reel and an improved silk frame. The patent then is, not for a mode of dying alone, but of dying and finishing silks; and this, by means of the use of both machines, so that it is a patent for the machines in combination, and not separately. If so, then the defendants may use either of the machines separately, without infringing the patent right; for the exclusive right of the combination only is secured to the plaintiffs. In this view, there is an end of the present suit; for it is admitted by the plaintiffs, that the defendants did not use the silk frame, and that the only infringement, for which they seek a recompense, is the use of the reel. But if the patent could be construed, as a patent for each of the machines severally, as well as in the combination, then it would be void; because two separate inventions cannot be patented in one patent. And the same objection would lie against it, if it were to be construed as a patent for each of the machines severally, and not in combination. If, however, all these difficulties could be surmounted, and the patent were to be construed as a patent for an improved reel and an improved frame separately, there remain other insuperable objections. There is no pretence, that the patent can be sustained for the whole reel, as a new invention, although some part of the language of the specification might lead to the conclusion, that the plaintiffs so intended to claim; for reels were in use before for the same purpose. And if it were otherwise, the plaintiffs could not recover; for the defendant does not use precisely the same machine,* and if he did, the patent would be broader than the invention, and so void. The patent therefore must stand, if at all, as a patent for the improvements only upon the old reel. And what the improvements claimed by the plaintiffs are, must be decided exclusively by the terms of their specification. The words of the specification, after describing the improved reel, are:—“There has been, it is said, a reel heretofore in use for the like purposes; but this, if it ever were so used, consisted of four arms, or two cross pieces, adjusted to a square axle; and the set of arms were kept separate or fixed upon the axle, not by a screw, but by pins passing through holes in said axle. Instead of pins affixed *926to the arms, there were common tenter-hooks driven into the inner side of the arms, and the whole so constructed, as to be utterly inapplicable to the purposes of dying silk or other goods without great injury. The machine, for which the applicants claim a patent, is, in all material respects, an improvement upon this.” This is the whole statement of the improvements in the reel, in the plaintiffs’ specification. And assuming, that it is not utterly defective, from omitting to specify the particular improvements, for which the patent is claimed, (for a general statement, that the patented reel is in all material respects, without stating what these are, an improvement on the old reel, is no specification at all,) the plaintiffs have bound themselves to the improvements so specified, and cannot now claim beyond them. Rex v. Cutler, 1 Starkie, 354. Now, the plaintiffs have specified no particular number of arms to be used in their machine, as among their improvements, and therefore no particular number of arms is patented. The machine is stated by themselves to consist “of two sets of arms, each resembling in form the hub and spokes of a wheel, without the rim or fellies.” There is, therefore, nothing new in this particular; and, in point of fact, the plaintiffs use eight arms and the defendants ten arms in their respective reels. The two principal improvements, actually specified, are the use of a screw, to separate gradually and keep apart the opposite arms of the reel, instead of a pin passing through a hole in the axle; and the use of oblique transverse pins to hold the selvages of the silk, instead of tenter hooks. Now, in point of fact, the defendant does not in his reel use the pins described in the specification, but staples with a small barb, which are at least as different in form and effect from the pins, as the pins are different from tenter hooks. And pins or hooks of all sizes and finish were proved at the trial to have been used for at least thirty years last past, for the same purpose. There is no pretence, that the staples and barbs used by the defendants are exactly in size, shape, and direction like the plaintiffs’. Then, as to the screw; it is a sufficient answer to the plaintiffs, that by their own showing the defendant never used the screw in his reels; but used a rack and pinion, which, it is agreed, is a different mechanical power. The only two improvements, therefore, which are specified, are not used by the defendant, either separately or in combination. How then is it possible to contend, that he has violated the plaintiffs’ patent?
This is not all. The pin or hook used for this purpose is not a new invention. It has been long in use, and, as was proved at the trial, at least for thirty years. I do not say, that a pin or hook was used exactly of the same shape, dimensions, and oblique position, as that used by the plaintiffs. But it is to be considered, that the mere change of the form or proportions of any mechanical apparatus is not, by the express terms of the patent act, to be deemed a patentable invention. And as to the screw, its use for the very purpose proposed by the plaintiffs, is completely described in the work cited at the bar, printed in 1789. The words are, “these frames are held together by means of a screw, so as to be easily let out, or taken in, according to the breadth of the cloth.” If, therefore, the patent could be considered as a patent for each of those improvements separately, it could not be sustained; for neither of them is new in substance. If, for the combined improvements, then, in the first place, the defendant has not used them; and, in the next place, the patent is broader than the invention; for, up to a certain point, the improvements existed before. The screw was in use for the same purpose, as early as 1789. But, if we could go beyond the patent and specification, and consider the patented improvements to be such improvements, as the plaintiffs now claim, it would not relieve the case from a single difficulty. The plaintiffs now claim in addition to the improvements already specified, 1st. The use of more arms than four to wind the silk in a spiral form. The silk was wound in a spiral form before; and surely it cannot be pretended, that the use of more than four arms on a reel or wheel was not known as well before as since the plaintiffs’ invention. Besides; the plaintiffs have not specified any particular number of arms as their invention, and they never used but eight; and if such use constitute a separate invention, the defendant is at least as well entitled to claim the use of his ten as his own invention. If adding, a given number of arms be an invention, adding a different number is not less an invention. 2dly. The plaintiffs claim the use of the side pieces to support and steady the screw during the operation. This is not, as I recollect, used by the defendants for the same purpose; nor, if used separately with the screw, is it any thing new. If, therefore, the whole improvements, as now claimed, were specified in the schedule, the plaintiffs could not legally support a patent for them separately; and if they are claimed in combination, then the defendants have not infringed upon that combination; and if they had, the plaintiffs could not recover, because the combination up to a certain point existed (as they have shown) before. So that to sustain their patent in point of law, the plaintiffs are driven to construe it to be for the combination, and then the evidence of infringement fails them; and to sustain their suit in point of fact, they are obliged to con-' strue their patent to be for the improvements severally, and then they fail upon the clearest principles of law applied to the facts.
I have thus gone over the whole grounds of this cause, and in every possible view, in which I can contemplate the law or the facts of the case, the verdict is wrong. Under such *927circumstances, to suffer it to stand, would be a mockery of justice. It would be surrendering the whole rights of the community to the mistakes or prejudices of juries. The public ought to know, that if a jury should be misled by the ingenuity or zeal of counsel, there is a redeeming spirit in the law itself; and that no judge in these times can be weak or wicked enough to abandon, what his duty plainly and peremptorily enjoins upon him. Let the verdict be set aside, and a new trial granted.
New trial granted.