delivered the opinion of the court.
Phis cas.e comes here on a writ of error to the Circuit Court -for' the western district of Pennsylvania, in an action brought by the plaintiffs, assignees of James Harley, against the. defendants, for the' infringement of a patent granted to Harley for ¡an improvement in the . lode of casting chilled rollers and other metallic cylinders and cones, in. which judgment .was rendered for the defendants. On the trial it appeared in evidence that it had long been a desideratum to find out some mode by which iron rollers or cylinders,, could be so cast that when the metal was introduced into the mould it should cause a swyrl or rotatory motion, by which the flog or dross would be thrown into the céntre, instead of the surface of the cylinder. By the old mode, the metal .was conveyed from the furnace-to the mould through a gate, or pipe, placed in a horizontal or perpendicular direction. The mode alleged to have been invented by Harley is thus described in the specification annexed to the patent :• “ The tube or tubes,or passages called gates, through which the metal, to be conveyed into the moulds shall not enter the mould perpendicularly at the bottom, but slanting, or. in a direction approaching to a tangent of the cylinder, or if' the gates enter the moulds horizontally or nearly so, shall not enter in the. direction of the axis of i' ie cylinder, but in a tangent form, or inclining towards a tangent of the cylinder.”-
■ This- was the thing patented, consisting solely in changing the direction of the tube, which conveyed the metal to the mould, *205 from a horizontal or perpendicular position to an angular one-; it produced the desired effect and was highly useful.
The novelty of the invention was much contested at the trial, but as the case turned on - other points, that becamé an immaterial question; -as the case comes before us; on exceptions to the charge of the court, which assumed that Harley was the original and true inventor of the improvement, and put the case to the jury on the following facts, which were in full proof, in nowise contradicted, and admitted to. be true.
' That-Harley was employed by the defendants at their foundry in-Pittsburgh, receiving wages from them by the week; while so employed, he claimed to have.invented the improvement .patented, and after several unsuccessful' experiments made a. successful one in October, 1834; the experiments were made in the defendants’ foundry,- and wholly at their expense, while Harley was receiving his wages, which-were increased oh account of the useful result. Harley continued .in their employment on wages until January or. February,. 1835, during all which, time he made rollers-for them; he often spoke about procuring a,patent, and prepared more than one set of papers for the purpose; made his application the 17th February, 1835, for a patent; it was granted-on the 3d of . March, assigned to the plaintiffs on the 16th of March, pursuant to an agreement made in January.
While Harley continued in the defendants’ employment, he proposed that they should take out a patent and purchase his right, which they declined; he made' no demand on them for any compensation fdr using his improvement; nor gave them' any notice not to use it, till, on some misunderstanding on another subject, he ga'Ve them such notice, about the time of his leaving their foundry, and after making the agreement with the plaintiffs, who owned a foundry in Pittsburgh, for an assignment to them of his right. ' The defendants continuing to make rollers on Harley’s plan,, the present action was brought in October, 18-35, without any previous-notice by them. The court left it to the jury to decide what the facts of the case were; but if they were as testi-. . lied, charged that they would fully justify the presumption of a license, a special privilege, or grant to the defendants -to use the invention; that the facts amounted to “-a consent and allowance of such use-,” and show such -a consideration-as would support ' *206 an express.license or grant, or call- for the presumption of 'one to meet the justice of the case, by exempting .them from liability; having-equal effect with a license, and giving the defendants a right to the continued use of the invention. The court- also charged the jury, that the facts of the case, which were not controverted, brought it within the provisions of the 7th section of the act of 1839, by the unmolested, notorious use of- the invention, before the application'for a-patent by Harley, and that nothing had been shown by the plaintiffs to counteract the effect off this prior use. That as assignees of Harley; the plaintiffs-- stand in his place, as to right and responsibility; they took the assignment of the patent, subject to the legal consequences of his previous acts, and-connecting these with the absence of an assertion of a right adverse to the defendants use till this suit was brought, protected the defendants from liability for any damages therefor.
The exceptions to the charge were confined to these two points, which constitute the only subject for our consideration. Whether these exceptions are well taken or not, must depend on the law as it stood at the emanation of the patent, together with such changes as have been since made; for though they may be -retrospective in their operation, that is not a sound objection to their validity; the powers of Congress to legislate upon the subject of patents is'plenary by the terms of the Constitution, and as there aré no restraints on its exercise, there can be no limitation oí their right to modify them, at their pleasure, so that they do not take away the rights of property in existing patents.
When the patent to Harley was granted, and this suit brought, the acts of 1793 and 1800 were the tests of its validity, but the 21st section of the act of 1836 repealed all existing laws on the subject, of patents, with a proviso, that all suits brought before may be prosecuted in the same manner as if that act- had not been passed, “ excepting and saving the application to any such action, of the provision of the 14th and 15th sections of this act, so far as they may be applicable thereto.5’ This repeal, however, can have no effect to impair the right of property then existing in a patentee, or his assignee, according to the well-established principles of this court in
In Pennock
v.
Dialogue, this court held,-in 1829, “That if an inventor makes, his discovery public, looks on, and permits others freely to use it, without objection or assertion- of. claim to the invention, „of which the public .’might take notice; he abandons the inchoate right' to 'the exclusive use of the invention, to which a patent would have entitled him, had it been applied for, before such use, and that 'it makés no difference in the principle, that the article so publicly used, and afterwards patented, was made by a particular individual who did so by the private permission óf the inventor.”
On this construction of the acts of ,1793 and 1800, Harley’s patent would have been void, on the evidence in this case. Such seems to have been the sense of Congress, as expressed,in,the act of 1832, which authorized the issuing a new patent, when', an original one was invalid by accident, inadvertence,-or mistake, arid without "any fraudulent intent, by reason óf the terms of the 3d section of the act of 1793 not having been complied, with, “Provided,however, that such new patent so granted shall.in all respects be liable to the same matters of objection and defence as any original patent, granted under the said first-mentioned act. That no public usé or privilege of the invention so patented, derived from or after the grant of the original patent, either under any special license of the inventor, or without the corisent of the patentee that there shall be free public use thereof, shall.in any manner prejudice the right of recovery for any use or violation of his invention after the' grant of such new patent, as aforesaid.”
This act is an affirmance of the principles laid down by this court in the three cases before referred to,- and as the exception to. the proviso is limited to an use of the invention under a spe-' cial license of the inventor after the grant of the original patent, it leaves the use .priorfo the application for such patent clearly obnoxious to the principle established in
The same conclusion follows froin the 15th section of the act
*208
of 1836, which declares, that if the thing patented
“
had been in public use, or on sale, with the consent and allowance of the pátentee, before the application for a patent,” judgment shall be rendered for the defendant with costs.
It would, therefore, be no strained,-if not the fair construction of this act, if under such and the other circumstances in evidence in the cause, the court had charged the jury, that if they believed the- witnesses, the patent subsequently obtained was void. The Circuit Court, however, did not go so far: they held that the defendants might, continue to use the inventibn, without saying that the public might use it, without liability to the plaintiffs, in which we think there was no error in their direction to the jury; that they might presume a license or grant from Harley, or on the legal effect of the uncontroverted evidence as to the right of recovery, by the plaintiffs, or on the construction of the acts of 1793, 1800, - 1832, and 1836. ,
The remaining exception is to the charge of the court below, on the effect of the' 7th section of the act of 1839, which is in these words: “ That every person or. corporation who has, or shall have purchased or constructed any newly-invented machine, manufacture, or composition of matter, prior to the application by the.inventor or discoverer of a patent, shall-be held to possess the right to useand vend to others to be used, the specific machine, manufacture, or composition of matter, so ’ made or purchased, without liability therefore to the. inventor, or. any other person interested in such invention; and no-patent'shall be held invalid by reason of such purchase, sale,-or use prior to the application ■for a patent as aforesaid, except on proof pf abandonment- of such invention to the public, or that such purchase, sale, or prior use has been for more than two years prior W such application for a patent.” Pamphlet Laws, 1839, 74, 75. '
The object of this provision is evidently twofold ;■ first, to protect tlie person who has used the thing patented, by having pur *209 chased, constructed, or made the machine, &c., to which the invention is applied, from any liability to the patentee or his assignee'. Second, to protect the rights, granted to the patentee, against any infringement by any other persons. This relieved him from the. effects of former laws and their constructions by this court, unless-in case of an abandonment of the invention, or a continued prior use'for more than two years before the application for a patent, while it puts the person who has.had such prior use on the same footing as if he had a special .license from the inventor to Use his invention; which, if given before the application for a patent, would justify the continued use after it issued without liability.
At the trial below, and here, the plaintiff’s counsel have contended, that this act cannot apply to the present case, iuasmuchas the protection it affords to the .person who had the prior use, is confined to the specific' machine, &c<, and does not extend to such use of the invention, or- thing patented, if it does not consist of a-machine, &c., as contradistinguished from the new mode or manner in which an old machine or its parts operates, so as to produce the desired effect; but we think that the law does not admit of such construction, whether we look at its words or its manifest objects, when taken in connection with former laws, and the decisions of this court in analogous cases.
The words “such invention” must be referred-baclc to the preceding part of the sentence, in order to ascertain the subject-matter, to which it relates, which is none other than the newly-invented machine, manufacture, or' composition of matter constituting the thing patented; otherwise these words become senseless when the invention is-uot strictly of a machine, &c. Now, in-'the present case, we find the invention consists solely in the angular direction given to the tube through which the me.tal is conducted into the cylinder in which the roller is.cast. Every part of the machinery is old, the roller itself is no part-of the invention, and cannot be the machine, manufacture, or composition of matter contemplated by Congress, nor ban the word
‘f
specific’-’ -have any practical effect unless it is applied to the thing patented,-whatever it may be, without making a distinction between a machine, &c.', and the mode of producing a useful, result by the mere direction ' given to one of the parts of ah old machine. Such a construction
*210
■' is not justified by the language of the law, and would défeat both of its objects. ■ If it does. not embrace the- ease before us, the consequence would be that the use of the invention, under the circhinstances in' evidence, would, according to the decision in
We, therefore, feel bound to take the words “newly-invented machine, manufacture, or. composition of matter” arid “such invention,” in the act of 1839, to mean the “invention pátented,” and the words “specific machine,” to refer to.“the‘thing as originally invented,” whereof the right, is secured by patent; hut not to any newly-invented improvement on a thing once patented. The use of the invention before an application for á patent must be the specific improvement then invented and used d>y the person who had purchased, constructed,-or used the machine-to which the invention is applied: so construed, the objects of the act of 1839 are, accomplished; a different construction would *211 make it- necessary to carry into all former laws the same literal exposition of the various term's used to express the same -thiug, and thereby changing the law according to ¿very change of pie re phraseology, make it a labyrinth of inextricable confusion.
We are, therefore, of opinion that there is no error in the charge of the court below, and that its judgment be affirmed.
order.
■ This cause came on to be heard on the transcript of the record from the Circuit Court of the United States for the western district of Pennsylvania-, and was'argued by counsel. On consideration whereof, it is ndw here ordered and adjudged by this court, that the judgment of the said -Circuit Court in this cause be and the same is hereby affirmed, with costs.