Mr. Justice Blatchford

delivered the opinion of the court. He recited the facts as above stated, and continued:

Many questions were discussed at the hearing which we deem it unnecessary to consider, because we are of opinion that the- disclaimer made has the effect to so limit the construction of the claims of the reissue that the defendant’s machine cannot be held to infringe those claims. The opposition ;to the extension proceeded, among other things, on the ground that reissue No. 1,948 was so worded as to cover a machine having a stationary die and a movable bunter — one not within, the language or the scope of the original patent, not indicated *640 therein as the invention of Allen, and not described, and a substantially new and different invention. That the Commissioner. intended that the extension should not be granted unless there should be a disclaimer of all claim to have No. 1,948. cover a machine with a stationary die and a movable bunter, and that the second disclaimer filed was such a disclaimer, and that the patent extended cannot be held to be one which covers, by. any claim, the defendant’s machine, is, we think, entirely clear.

The Commissioner, in his decision, says, that the “ interpolations of new matter” in No. 1,948 “have been disclaimed,” and that such disclaimer renders “ the scope of the patent unequivocally that of the invention originally described and illustrated in drawing and model.” The disclaimer is referred to as limiting the scope of the patent, that is, the extent of its. claims, and as reducing such scope and extent to what the drawings and model illustrated, namely, a movable die and a stationary bunter, to the exclusion of a stationary die and a movable buncer. The Commissioner adds, that it had been the subject of much contention, in the application for the extension, whether the modification, of having a stationary die and a movable anvil, which, he says, it was admitted, effected . materially superior results in heading the larger sizes of shells, was, in legal contemplation, an. equivalent construction mechanically improved, or a substantive invention; and that he is so entirely convinced that the matter introduced into the reissue, describing the holding die as stationary, and the bunter as movable, was new matter describing a substantially different invention from the original, possessing different functions, that he 'had required, as a condition precedent-to extension, that this new matter should be absolutely disclaimed. The new matter introduced into the reissue in respect to the moving of the bunter or die E, was introduced into the descriptive part, by inserting the words, “or that” (the die E) “may be carried -against the die D by similar mechanism to F and H',” but it was also introduced into the two claims, by the use of the words “ substantially as described,” in those claims.

This reissue took place under § 13 of the act of July 4, *641 1836, ch. 357, 5 Stat. 122, which provided for a surrender and the issuing of a new patent “ for the same invention,” “ in accordance with the patentee’s corrected description and specification.” This provision was repeated in § 53 of the act of July 8, 1870, ch. 230, 16 Stat. 205, now § 4916 of the Revised Statutes, with the additional 'enactment that “ no new matter shall be introduced into the specification.” But where new matter was, even before the act of 1870, introduced into the description, and in such manner as to enlarge the claim, and cause the patent to. be not “ for the same invention,” the reissue was invalid to the extent that it was not for the same invention.

It is. quite clear that Allen had not, before the granting of the original patent, made any machine in which the die D was stationary and the bunter movable. If that arrangement was a “ new improvement of the original invention,” and was invented by Allen, and after the date of the original patent, he could, under § 1,3 of the act of 1836, have had a “ description and specification” of it-“.annexed to the original description, and specification,” on like proceedings as in the casé of an, original application, and it would have had “ the same effect, in law,” from “ the time of its being annexed and recorded,” “as though it had been embraced in the. original description and specification;” or he could have applied for a new patent for the improvement. Such last named provision' of § 13 of the act of 1836 was repealed by the act of 1870, and was not reenacted therein, nor is it found in the Revised Statutes. But it was never lawful to cover, by the claims of a reissue, an improvement made after the granting of the original patent.

The statute in force in regard to disclaimers, when the disclaimers were filed in this case, was § 54 of the act of 1870, which provided, “ that whenever, through inadvertence, accident or mistake, and without any fradulent or deceptive intention, a patentee has claimed more than that of which he was the original or first inventor or discoverer, his patent-shall be valid for all that part which is truly and. justly his own, provided the same is a material or substantial part of the thing patented; and any such patentee, his heirs or assigns, whether *642 of the whole or any sectional interest therein,' may, on payment of the duty ^required by law, make disclaimer of such parts of the thing patented as he shall not choose to claim or hold by virtue of' the patent or assignment, stating therein the extent of his interest in such patent; said disclaimer shall be in writing, attested by one or more witnesses, and recorded in the Patent Office, and it shall thereafter be considered as part of the original specification, to the extent of the interest possessed by the claimant and by those claiming under him after the record thereof.” This word “ claimant ” is an evident error, for “ disclaimant,” as “ disclaimant ” is the word used in § 7 of the act of March 3, 1837, ch. 45, 5 Stat. 193, which was the first státute providing for a disclaimer. This error is perpetuated in § 4917 of the Revised Statutes.

It is a patentee who “ has claimed more than that of which he was the original or first inventor or discoverer,” and only “ such patentee,” or his assigns, who can make a disclaimer; and the disclaimer can be a disclaimer only “ of such parts of the thing patented as he shall not choose to claim or hold by virtue of the patent or assignment.” A disclaimer can be made only when something has been claimed of which the patentee was not the original or first inventor, and when it is intended to limit a claim in respect to the thing so not originally or first invented. It is true, that, in so disclaiming or limiting a claim, descriptive matter on which the disclaimed claim is based, may, as incidental, be erased, in aid of, or as ancillary to, the disclaimer. Rut the statute expressly limits a disclaimer to a rejection of something before claimed as new or as invented, when it was not new or invented, and which the patentee or his assignee no longer chooses to claim or hold. It is true, that this same end may be reached by a reissue, when the patentee has claimed as his own invention more than he had a right to claim as new, but, if a claim is not to be rejected or limited, but there is merely “ a defective or insufficient specification,” that is, description, as distinguished from a claim, the only mode of correcting it was and is by a reissue.

It is apparent that the Commissioner, when he said that the disclaimer affected “the scope of the patent,” and that the *643 matter introduced into the reissue was “new matter, describing a substantially different invention from the original, possessing different functions,” and that he had required it to be absolutely disclaimed, “ as a condition precedent to extension,” meant that he had required such new matter, that is, the arrangement of a stationary die and a movable bunter, to be disclaimed, as an invention of Allen, covered by the reissue.

"What was done was in accordance with this view. In the first disclaimer,, that of February 4th, 1874, it is said, that by inadvertence, accident, or mistake, the words “ or that may be carried against the die D by similar mechanism to F and H'-” were inserted in the descriptive part of No. 1,948, and were not in the descriptive part of the original patent. Thereupon, the petitioners disclaim, not such descriptive words, as a description merely, but they disclaim “ the movable die E as being of the invention of ” Allen, but with this limitation or reservation, “ except in so far as the same, by fair construction, may be deemed the mechanical equivalent of the die E described and shown ” in the original patent arid its drawings. It was sought to reserve the question of the mechanical equivalency of the stationary die and movable bunter with the movable die and stationary bunter, and not have the disclaimer absolutely reach and cover the former, but still leave the claims to cover it. But this was evidently not satisfactory to the Commissioner, and he required a further disclaimer. So, the one of February J.3, 1874, was filed, which states, on its face, that it “ is absolute, and is filed as an additional disclaimer” to the first ene, “ in which certain reservations were made.” In this second disclaimer, the language as to the inserted words is-the same as in the firsthand the statement of disclaimer is, that the “ petitioners disclaim the said movable die E (called a bpnter) as being of the invention ” of Allen, “ thus leaving the description of said die E the same as shown in the ” original patent and drawings. The reservation was expunged.. The effect, of the, disclaimer was to limit the claims of the reissue to-a machine with the stationary die E, shown in the original patent and, drawings, and to prevent their any longer covering, even if they had before covered, a movable die E, or bunter...

*644 Such was the effect of the disclaimer on the reissue, without reference to the extension. But, the certificate of extension itself states, that the executrix had “ filed a disclaimer to that part of the invention embraced in the following words: ‘ or that may be carried against the die D by similar mechanism to F and H',’ ” and what is extended is No. 1,948, with such disclaimer. After an extension has been obtained on the condition precedent of making such disclaimer, the disclaimer cannot be held inoperative as respects the extended term.

"We regard this case as falling within the principles laid down in Leggett v. Avery, 101 U. S. 256. There the original patent was issued in October, 1860. It was surrendered and reissued in Juné, 1869, and extended in October, 1874. As a condition of obtaining the extension, the patentee disclaimed the specific claims which the defendants in the suit were charged with infringing, the extension having been opposed, and the Commissioner having refused to grant it unless the patentee would abandon all but one of the six claims of the reissue, there having been but one claim in the original patent. This was done, and the extension was granted for only one of the six claims, which one the defendants had not infringed. Three days after the extension was granted a reissue was applied for, including substantially the claims which had been thus disclaimed. The reissue was. granted, two of the claims in it being for substantially the same inventions which had been so disclaimed before the extension, and for different inventions from the invention secured by the patent as extended. A reference to the record of the case in this court shows-, that the Commissioner decided that the extension would be granted provided-the disclaimer should be filed, and that the disclaimer concluded with the words “ reserving right to reissue in proper form.” This court held, that the Commissioner erred In allowing, in the- second reissue, claims which had been expressly disclaimed, because the validity of such claims had -been considered and decided with the acquiescence and express disclaimer of the patentee; and that this was a fatal objection to the validity of the second reissue.

The acquiescence and disclaimer must be regarded as equally *645 operative to prevent those who hold the reissue in suit, whether in respect to the time before or after the extension, from .being heard to allege that persons who use machines with a stationary die D and a movable bunter E. infringe the claims of the reissue. The disclaimer was one of the fact of invention. It could not lawfully be anything but a disclaimer of the fact, either of original invention, or of first invention. It was not merely the expunging of a descriptive part of the specification, involving only the propriety of inserting such descriptive part in the specification, but it was a disclaimer of all claim based on such descriptive part, because the claims were made to cover such descriptive part, by the words “ substantially as described,” in the two claims. The question of fact is not open now as to whether Allen invented at any time the stationary die I) and movable bunter E, or as to whether it was, or is, or could be, a mechanical equivalent for the movable die I) and stationary bunter E, because those questions are concluded by the disclaimer.

It is conceded by the plaintiff, that, if by the operation of the disclaimer, it is estopped to say that a stationary die D and a movable bunter E are the equivalent of the movable dieD and the stationary bunter E, the defendant does not infringe.

The decree of the Circuit Court is reversed, with costs to the United States Cambridge Company, on both appeals, and the case is remamded to that court, with direction to dismiss the bill, with costs.