after making the foregoing statement, delivered the opinion of the court.
The contention of the appellant has been narrowed by counsel and by the experts to the assertion that the Perkins “method is characterized by a new and useful way of applying heat to the pavement, to wit, by sending a flame blast into direct contact with the pavement surface.” This, it is insisted, must follow from an intelligent reading of the claim in connection with the specification. The specification, instead of aiding, explicitly and absolutely forbids, the proposition. A blast, it is true, is the certain result of the one apparatus which is described as a means of applying the heat; but, unwilling to abide by that, the patentee proceeded to add:
“The heating of the surface may be accomplished in various ways, and by means of various forms of apparatus; and, while I have shown but one form, * * * I would have it understood that I do not limit myself to any particular form of apparatus.”
The reference, of course, is to existing and known “ways” and “forms of apparatus,” and not, as one of the experts irrelevantly sug-gesfed, to “different and improved forms of apparatus affecting the efficiency of the method, * * * since devised,” which “all retain the obviously best idea of using a liquid fluid, * * * not essential to the flame blast, and, of course, not essential to the contact of the flame with the pavement.” According to the same witness, the Perkins patent was “the first disclosure in the art of any apparatus by which heat may practically be imparted to an asphalt pavement on this principle,” and the well-chosen words of the first claim are in strict harmony with the unmistakable purpose of the patentee to include in his method all of the “various ways” possible of heating the surface to be affected, and the operation of every *973known form of apjiaratus capable of being used in any way to the accomplishment of the proposed end. It was then well known “that heat could be used to soften a Trinidad asphalt pavement at the spot to be repaired.” The process of softening the hardened edges of a pavement in course of construction, as the work ceases and is resumed from time to time, was familiar. As a means of bringing heat to bear on a spot of pavement to be softened, the apparatus of Crochet was known, and that a like device could be used with a measure of success upon the asphalt pavements in common use in this country was established in the case in the Second circuit to which reference has been made. Another objection to the proposed limitation of the claim by making it read “a blast of heat,” or “a strong blast of heat,” in lieu of the unqualified word “heat,” is in the fact that the third claim, which contained the additional words, was withdrawn by the patentee upon a ruling or declaration of the patent office that the first and third claims were the same in substance, and could not both be permitted to remain in the case. That was not merely a casual expression of opinion by an examiner, but was in effect a requirement that one or the other of the claims be withdrawn, and no reason is perceived for not applying the ordinary rule. Having voluntarily abandoned the claim for a method limited to the use of “a blast of heat,” the patentee or his assignee may not now insist that a broad claim, containing no suggestion of such intention, shall nevertheless he subjected by construction to the same restriction. This point, in view of the reservation already considered, is unimportant, and might be passed; but it is to be observed that, if the third claim was withdrawn by mistake, a correction should have been sought in the patent office, either by a surrender and reissue, or possibly by a new application. It is not within the rightful power of the courts to enlarge or restrict: the scope of patents which by mistake were issued in terms too narrow or too broad to cover the invention, however manifest the fact and extent of the mistake may he shown to have been. The problem which Perkins undertook to solve, it seems clear, was one which invoked the powers of invention, but it was much more narrow than it has been treated. It was not to find a method and means of repairing asphalt pavements by “subjecting the spot to he repaired to heat, adding new material, and smoothing and burnishing it.” It was to find a new and better method and means of accomplishing the one step of heating, and if a patent on the method, as distinguished from the apparatus, was to be sought, and was allowable, a more appropriate, if not the only proper, description would have been, not “a method of repairing asphalt pavement,” but a method of heating an asphalt pavement for the purpose of repair, or, better than that, for the purpose of softening it at the spot to be dealt with, which, of course, might be for other purposes than repair, such as cutting through in order to reach or lay pipes underneath. Indeed, there seems to have been no reason for restricting either the method or apparatus to use upon any particular pavement. It is capable, evidently, of efficient employment upon all known kinds of asphalt pavement, and upon any accessible surface which it may be desirable to heat, but, of *974course, with effects varying always according to the different qualities of the material operated upon.
Treating the invention as being simply for a method of applying, heat, we incline to the opinion of one of the experts that the method itself was separately patentable. Though brought into play by a special apparatus for which Perkins sought and obtained another patent, it seems to be in part the result of elemental and natural forces, and not merely the functional result of the apparatus, and is therefore not within the doctrine of Locomotive Works v. Medan, 158 U. S. 68, 15 Sup. Ct. 745, 39 L. Ed. 899. Once the apparatus was perfected, however, the process followed as a matter of course, and .the inventive power by which it was evolved is not to be distinguished from that expended in devising the apparatus. The primary conception embodied in the apparatus is a blowpipe. Starting with that, and with the fire box of Crochet, with whose patent Perkins seems to have been familiar, and with a knowledge of the properties of gasoline or other “liquid fluid” which might be forced by atmospheric pressure through supply pipes to tlie burners, the task was not one for a pioneer. The apparatus of Crochet, as pointed out by Dayton, was defective and objectionable for reasons which are so obvious that they must have been anticipated; but the more serious objections, it is evident, could be removed by substituting for the grate bottom and the live coals any form of apparatus capable of producing and directing a blast of flame against the plate below. Such a flame thrown uniformly upon the thin sheet-metal plate of the device, so placed and adjusted as to be “a little above the surface of the pavement,” could hardly be less potent than a direct impingement of the flame to produce the required effect upon the material to be softened, either for removal or for mixture with added new material. Whether' in that way the thin crust could be produced which the direct contact of flame causes, the evidence does not show, but whether it could or could not is for the present purpose not important. The production of the crust is not a part of the process claimed, and, it is conceded, could not be. At most, it is an incidental, perhaps invariable, result of the practice of the process in the one way and by means of the one form of apparatus described. The testimony is that only by experiment was that result discovered or discoverable, and it does not appear when the discovery was in fact made, — probably not before the patent was issued, else it would, if possible, have been made th'e subject or incident of a special claim. It is unnecessary to go further into details. While it has been determined, and stands unquestioned in the case, that Perkins invented an improved and-much more efficient apparatus for repairing-asphalt pavement than any before known, and incidentally developed ■ — invented—a new and useful method of applying the heat, yet, neither by itself nor in connection with the other steps mentioned in the claim, is that method covered by the patent.
The claim would seem to be invalid even if it could be said that the word “heat,” as used, means a blast or strong blast of heat. So read, or read as it stands, is it not for an aggregation of steps which do not constitute k patentable combination? Whether the old material is *975heated and softened in one method or by one means or another, the addition of new material seems to be a separate and independent act, and equally and more unmistakably so the final act of smoothing and burnishing. If these steps may be regarded as constituting a single process, because the final result is a repaired pavement, then, with equal propriety, and without constituting an aggregation, the preparation of the additional material to be used — all the steps of that preparation, and the bringing of it to the place for use, including the means used for bringing it — might be included in the claim. ,
The decree below is affirmed.