specifications of the patent last surrendered were amended by omitting the objectionable parts. Patents are constantly reissued for portions of the specifications and claims in the identical language of the original patent. Each claim in its nature substantially and in effect covers a distinct and separate invention, and is an independent patent in substance and effect. It might be the subject of an independent patent, and if in any reissue, so far as the patents are identical, those claims are valid in the reissued patent having another or additional valid claim, or a modified claim, or some other change in the specifications, I do not perceive why they would not be valid in a patent limited to them alone. If they can all stand together, I do not see why a reissued patent covering the identical claims by themselves may not stand and be valid. Patents may be reissued in divisious. It is not necessary that all claims in the reissue should be included in one patent. They are often issued in divisions, and I suppose a patent might be reissued in divis ions in the identical language as to some of the claims, the changes being included in another and separate division or patent-that is to say, all claims or inventions which are fully covered and operative may be reissued by themselves in one division in the identical language of the original surrendered patent, and all other claims, or the amendments to the specifications, and covering the invention shown by the amended specifications, in another division or patent. I do not see why a part of the original claims may not be reissued in one division in identically the same language as in the original patent, and the rest in auother. If this can be done without affecting the validity of the reissue, and a party finds that he has made a mistake and surrendered a valid patent and obtained a void reissue, I do not perceive why he may not fall back upon his old patent and have it reissued or newly-amended specifications embodying that portion which is valid. If parts which are identical are valid in connection with other parts in a reissue, I do not perceive why they should not be valid in a reissue containing no additional matter. Now, in this particular class of cases it is quite extensively claimed by the bar, I think, that the supreme and some of the circuit courts have made something of a departure in some of their late decisions upon reissues, including the reissue in question. Mr. Justice Field held Patent No. 5,799 to be void, while several of the circuit judges at the East held it to be valid. Where courts make a mistake, it may very properly be conceded that a party may very well make an honest mistake himself. On the argument of the plea, my attention has been called for the first time to the case of Gage v. Herring (107 U. S., 646), in which, I think, the principle involved in the plea is distinctly determined. The court says: The invalidity of the new claim in the reissue does not indeed impair the validity of the original claim, which is repeated and separately stated in the reissued patent Under the provisions of the patent act, whenever through inadvertence, accident, or mistake, and without any willful default or intent to defraud or mislead the public, a patentee in his specification has claimed more than that of which he was the original and first inventor or discoverer, his patent is valid for all that part which is truly and justly his own, provided the same is a material and substantial part of the thing patented and definitely distinguishable from the parts claimed without right; and the patentee, upon seasonably recording in the Patent Office a disclaimer in writing of the parts which he did not invent or to which he has no valid claim, may maintain a suit upon that part which he is entitled to hold, although in a suit brought before the disclaimer he cannot recover costs. Rev. Stats., secs. 4917, 4922; O'Reilly v. Morse, 15 How., 62, 120, 121; Vance v. Campbell, above cited. A reissued patent is within the letter and the spirit of these provisions. If a reissued patent is within the letter and spirit of these provisions, as stated, and "the invalidity of the new claim in the reissue does not indeed impair the validity of the original claim, which is repeated and separately stated in the reissued patent," it is not apparent to my comprehension why a second reissue embracing the valid claim alone of the original patent would not be valid. I cannot, therefore, say that the Patent No. 10,267 is void by reason of anything asserted in the plea upon the grounds set forth. The plea must, therefore, be overruled. With reference to the filing of the proposed so-called amended plea, I think it is not within the reasonable discretion of the court to allow it to be filed at this late day. In view of the circumstances of this case, as they appeared before this court in the various stages of the proceedings, I think it would be an abuse of its discretion to allow the plea to be filed, if it were otherwise a proper plea. In fact, the proposed amended plea sets up all the defenses that can be made to a patent, and it would involve the trial of the whole case with the exception of the single question of infringement. The object of a plea, where there is some certain, single issue requiring but little evidence that will dispose of the whole case if sustained, is to try that issue without putting the parties to the expense of the trial of the case at large, and pleas are limited to a single defense or issue, unless by permission of the court the defendants are allowed to plead double. If the court allows this co-called amended plea to be filed, it would allow parties to try all the issues in the case with the exception of the one issue as to infringement, and it would be necessary to try the whole case on the merits by piecemeal. Besides, it comes too late. After this plea was originally filed it was stipulated that it stand for an answer, so far as it was available as a defense. An answer and replications were filed, and the parties commenced taking testimony. In the course of taking the testimony the attorney for the defendant ascertained the importance of having the case decided on his plea, provided it was good, and thought he was at a disadvantage in his then position. He therefore moved upon the affidavits to be relieved from the stipulation, taking the plea for an answer. He claimed, among other things, to have misunderstood the practice of the court. After argument the court, thinking there might be something in the plea, as this exact point had never been decided so far as it was aware, and, if good, it would save the expense of a trial, relieved the party from the stipulations and allowed the plea to be set down for argument. I did not think the exact question had ever been presented before, and when the argument was made upon the stipulation I had not seen the case of Gage v. Herring, supra, which I think decides the principle. I thought there was perhaps something in the plea. At all events I thought it was worthy of being carefully considered, for, if the plea is good, and the patent absolutely void upon its face, I saw no occasion for putting the parties to a great expense of going to a trial of all the issues in the case. I therefore set aside the stipulation and allowed the defendant to withdraw its answer in the case and set the plea down for a hearing. It was set down for a hearing and continued from time to time, until finally it came up for argument, counsel from Philadelphia coming on to argue the case on the validity of the plea. When the plea was called for argument, it was found that there had been a change of attorneys, and an application was made by the substituted attorney at the moment for leave to file the proposed so-called amended plea, which presents all the issues in the case with the exception of the one issue of infringement. I think, under the circumstances, it would be improper, and it would be an abuse of discretion, to allow this so-called amended plea to be filed at this late day. Leave to file the proposed amended plea is therefore denied. [United States Circuit Court-Western District of Pennsylvania.] LLOYD v. MILLER ET AL. LLOYD-PUDDLING-FURNACES. Decided February 12, 1884. 27 O. G., 101. Letters Patent No. 135,650, granted February 11, 1873, to E. Lloyd, for au improvement in puddling-furnaces, construed and sustained, but held not to be infringed by the defendants. Mr. D. F. Patterson and Mr. E. C. Cotton for the complainant. ACHESON, J.: The plaintiff's Letters Patent No. 135,650, dated February 11, 1873, are for an improvement in furnaces for boiling, heating, and puddling iron. The objects to be obtained thereby, as stated in the specification, are the prevention of the rapid burning out of the hearth-plate and the base of the chimney or stack and the facilitating of the combustion of the inflammable gases in the furnace by supplying air thereto, thereby utilizing fuel and preventing largely the escape of smoke. The furnace described in the specification and accompanying drawing, aside from the plaintiff's improvement, is a puddling furnace of the wellknown kind, having the ordinary exit-flue leading into the high chimney or stack. The invention is thus described: "Beneath the hearth-plate c and a plate e" (which is merely the continuation of the hearth-plate under the neck) "is an air-conduit, G, which extends from the ash pit opening E to the back wall of the stack C, and communicates with this stack at its base by means of an opening, g. This will allow" (the specification proceeds to declare) "a current of air induced by the draft of the stack C to enter the stack at its junction with the flue h." The resulting advantages thereby secured (as is affirmed) are the following: First, the current of air so entering the stack will "violently turn back the flames rushing through the flue h," retard the escape of inflammable gases, and, mixing therewith, promote their combustion in the furnace; second, the air in its passage through the conduit G will absorb heat from the hearth-plate and plate e, and keeping down their temperature, preserve them; third, "and as the air impinges on the chimney at its base, these walls will be protected from the intense heat to which they are subjected in other puddling-furnaces." The claim is in these words: The air-conduit G, arranged beneath the hearth and communicating with the chimney or stack at the base thereof, for the purposes and in the manner substantially as described. It was not a new thing to let air circulate underneath the hearth of a puddling-furnace to cool and preserve it; and it is shown that for many years prior to the plaintiff's invention such furnaces were constructed with a passage-way or conduit for air beneath the hearth and extending from the ash-pit opening to the back wall of the stack, with an aperture through that wall outwardly into the external air, so that this conduit was supplied with air from both ends, the fresh air coming in at the stack-end passing underneath the base of the stack on its way to the ash pit. Nor was it new to promote combustion in the furnace by a supply of heated air drawn from underneath the puddling-hearth. I incline, however, to think that the plaintiff's method of construction, whereby communication is secured between the air-conduit G and the base of the stack by means of an opening into the stack, is new, at least in puddling furnaces; and, assuming that the defense of anticipation has not been made out successfully, I address myself to the inquiry whether the defendants infringe the plaintiff's patent. The distinguishing feature of the plaintiff's invention is the opening g into the stack at its base, whereby a current of air induced by the draft of the stack is permitted "to enter the stack." Great promi. nence is given to that opening in the specification and accompanying drawing, and, although not expressly mentioned in the claim, it is necessarily implied. It is, indeed, indispensable, for without the opening g there would be no communication whatever between the air-conduit G and the chimney or stack. Every advantage specified or contemplated is altogether due to that opening, which, in my judgment, is of the essence of the invention. The alleged infringing furnaces were constructed by William Swindell, under three patents, for improvements in metallurgic furnaces, granted to him in the years 1875 and 1878. In the defendants' furnaces the gas from the producer, where the fuel is consumed, is admitted to the bed through a number of ports arranged below an equal number of hot-air ports. A series of air-flues pass under the bed, but not in contact in with the bottom, and over the crown or arch of the furnace to the end where the gas enters, and the gas and air there meeting pass together into the combustion-chamber, which contains the iron to be worked. The ingoing air is heated, and becomes more and more heated as it passes over the arch toward the discharge-ports by reason of the flues through which it courses being in contact with alternate flues which conduct the waste heat from the combustion-chamber. Combustion begins when the gas from the producer meets the hot air, and, uniting, they enter the bed. The waste and heated products of combustion pass out of the opposite end of the bed into the flues which extend over the crown or arch of the furnace and lead to the stack. No part of the air enters the waste-flues without first passing through the combustion chamber, and it reaches the stack altogether through the wasteflues. It cannot be pretended, and, indeed, it is not urged, that the method of construction found in the defendants' furnaces secures the first two above enumerated advantages which appertain to the plaintiff's invention. Swindell's air-conduits have no tendency to cool the hearth-plate or bottom of the furnace, and he does not conduct into the stack a current of air to retard the escape of inflammable gases or promote their consumption in the furnace. There is, indeed, no connection or direct communication between his air-flues and the stack, the air, as we have reen, reaching the stack through the waste-flues after it has fully served its purpose in the combustion chamber. It is, however, earnestly contended that the Swindell, by a mere structural or formal change, has secured, and that the defendants enjoy, the third advantage due to the plaintiff's invention, viz, protection to "the walls of the chimney at its base" from the intense heat to which they are subjected in other puddling-furnaces. The plaintiff's theory is that the arched waste flues of the defendants' furnace are part of the chimney or stack, which, he insists, begins at the point where these flues leave the combustion-chamber, and, as at that point the air passing in through the air-flues absorbs heat from and tends to preserve the walls of the waste-flues, he maintains that there is an infringement of his patent. I have great difficulty in accepting the hypothesis that the arched |