determine. As the revocation of the power of attorney was thus conditional, I should not have felt myself at liberty to regard it as imperative.

The patent will issue as heretofore ordered.

B. J. HOBSON.-EX PARTE.

APPEAL FROM THE EXAMINERS-IN-CHIEF ON AN APPLICATION FOR THE REISSUE OF LETTERS PATENT FOR STOVE-PIPE DRUMS, GRANTED OCTOBER 3, 1871.

(Decided February 10, 1872.)

Mere incidents and results not patentable-Disclaimers in pending applica

tions.

Where currents of air have been treated by bringing them in contact with a smokepipe, which for this purpose was made to pass through a drum, and the internal structure of such drum is so modified as to secure continuous contact between the air and the pipe within the drum, in lieu of the interrupted contact of the former apparatus, the inventor of the modified form is not entitled to a patent, broadly, for the feature of "continuous contact," but only for those changes in the construction: by which this condition is attained.

In such an apparatus continuous contact between the air and the smoke-pipe is a mere incident of the construction-not the object aimed at. Whether it be regarded as a mere incident of the construction adopted or as an intermediate result from such construction, it is not patentable; nor can it give patentability to a claim otherwise inadmissible.

The office of a "disclaimer" in the specification of a pending application is to distinguish the invention covered by such application from previous inventions, and its effect is neutralized when it is contradictory of the claim and not explanatory of it. DUNCAN, Acting Commissioner:

This application relates to an apparatus by means of which the "waste heat" of stoves and furnaces-i. e., the heat contained in the gases that pass off through the smoke-pipe-is utilized for heating an inflowing current of air, which in its turn may be used for any of the usual purposes for which heated air is available.

The smoke-pipe is made to enter one end of a cylindrical drum, the length of which is several times its diameter, and in its passage through this drum is divided into several branches, which, however, reunite before the other end is reached. The drum is also provided with an ingress and an exit air-pipe, so arranged that the inflowing air will traverse the drum in the reverse direction of the outflowing current of smoke and gases. The described principle of operation is, that when the cold air first comes in contact with the smoke-pipe it absorbs caloric from it by reason of the difference of temperature between the two; and that, by reason of striking the least highly heated portion of this pipe first, and coming constantly in contact with surfaces more highly heated than those preceding, and of course more highly heated than the air itself, it

is constantly receiving additional increments of heat until it escapes through the exit-pipe and is led off for use as desired.

The claim of the original patent was confined to the precise construction shown. The claim now asked for upon reissue is much broader, being for

An apparatus, substantially such as is herein described, for utilizing heat by means of a current of external air striking first against that part of the apparatus which is least highly heated, and flowing thence in continuous contact with and toward the parts that are more highly heated.

It is manifest, from the context and from the reasons of appeal, that it is intended by this claim to cover all forms of air-heating apparatus in which the air passes in the reverse direction of the products of combustion, and in continuous contact with the surfaces heated by the same. The claim stands rejected upon the patent of Duryea & Ennis, dated April 30, 1867. In the apparatus covered by this patent the air and the heated gases are caused to enter a long rectangular chamber at its opposite ends, and to traverse the chamber in reverse directions. This chamber differs from applicant's drum in being divided by diaphragms into various compartments, and the smoke-pipe, instead of passing longitudinally through the chamber, is arranged vertically in the successive compartments, the different vertical sections being connected by short horizontal joints. Notwithstanding this peculiarity of construction, the inventors, as fully appears from their specification, fully understood the value of passing the two currents in opposite directions, by which means the cold air would first be brought in contact with the radiator (smokepipe) in the compartment nearest the smoke-outlet, and would leave the chamber at the point nearest to that at which the smoke-pipe enters it, and where consequently the heat is greatest.

It is true, the construction of the compartment which is the least highly heated is such that the cold air moves within it in the same direction with the escaping gases; but in the other compartments the contrariety of movement is completely developed, and even in the first one the fundamental condition of both inventions) is fully exemplified, viz., that the fresh air comes in contact with a surface hotter than itself, and thus is constantly absorbing caloric. It is also to be borne in mind that while in the drawing this chamber is shown as divided into but two compartments, yet the specification indicates that it is simply for convenience of illustration that the number is reduced to two, while in practice the number would be larger; and if we look upon the chamber as consisting of a series of compartments, whatever may be the relative movement of the currents in any particular subdivision, it still will be substantially true, as regards the general chamber itself, that the external air strikes first against that part of the apparatus which is least highly heated and that the two currents are moving constantly in the opposite directions, the air-current entirely enveloping the smoke-pipe from the beginuing to the end; and this substantially answers the requirements of Hobson's claim.

If it be objected that, by reason of the two currents flowing in the same direction in the first compartment, the air does not absolutely strike against the least highly heated portion of the apparatus first, and, therefore, that the reference is not an answer to applicant's claim, it must be replied that neither is it literally true that in applicant's heater the air strikes first against the least highly heated part of it, for the smoke-pipe passes out at the top of the drum while the ingress air-pipe enters at the bottom. In both cases, however, and in the one equally with the other, the description is approximately and substantially true. But appellant lays great stress upon the fact that in the reference the current of inflowing air, in passing from the first to the second compartment, for a short space is not in contact with the smoke-pipe, and he claims it as a patentable difference that the air should be caused to preserve continuous contact with the pipe containing the heated gases. But this must be regarded as a matter of degree merely, and not a difference in substance. In Duryea and Ennis's patent the principle of continuous contact is illustrated after the second compartment is reached, while applicant professes to have gone a step further and made the contact continuous from the beginning; and it is upon this as the sole feature of difference from the former invention that he asks a patent.

If, in doing this, he secures a better result, he is entitled to a patent for the structure of the apparatus by which he attains that result; but the element of "continuous contact" is a mere incident of this peculiar construction. It is not "continuous contact" that the inventor aims primarily to effect; his object rather is to secure the results which may arise in connection with such contact. But whether this degree of con. tact be regarded as a mere incident of the particular construction devised or as an intermediate result from such construction, it is not patentable, and its existence would not confer patentability upon a claim otherwise inadmissible. Viewed as a mere incident of the construction, there is no law or rule of practice that would justify a patent for it; and viewed as a result growing out of the construction adopted, (but, at best, only an intermediate, and not the objective result,) it seems to be closely analogous to the subject-matter of the eighth claim of Morse's patent, which was held by the Supreme Court of the United States in the suit of O'Reilly vs. Morse, 15 Howard, 62, to be invalid. In that case the court laid down the following doctrine:

Whoever discovers that a certain useful result will be produced in any art, machine, manufacture or composition of matter by the use of certain means, is entitled to a `patent for it, provided he specifies the means he uses in a manner so full and exact that any one skilled in the science to which it appertains can, by using the means he specifies without any addition to or subtraction from them, produce precisely the result he describes; and if this cannot be done by the means he describes, the patent is void; and if it can be done, then the patent confers on him the exclusive right to use the means he specifics to produce the result or effect he describes, and nothing more. And it makes no difference, in this respect, whether the effect is produced by chemical agency or combination, or by the application of discoveries or principles in natural philosophy known or unknown before his invention, or by machinery acting altogether upon mechanical principles. In either case he must describe the manner and process as above mentioned and the end it accomplishes; and any one may lawfully accomplish the same end without infringing the patent, if he uses means substantially different from those described.

This doctrine is fatal to the present claim, which, as before remarked, is shown by the context and by the reasons of appeal not to be limited to the means employed, but to include broadly continuity of contact between the air and the smoke-pipe when the two currents are passed in opposite directions. Such a claim, also, would be excluded under the ruling of Mr. Justice Miller, in Sangster vs. Miller, (2 Fish, 564,) as being for a "result from the arrangement and combination of parts." The language of the court in Sickles vs. Falls Co., (2 Fish, 202,) is also perti nent.

Neither is applicant's case helped at all by the "disclaimer" which he has incorporated in his specification as to the various features of the Duryea & Ennis's invention. The Office calls for disclaimers to be inserted in the specification of a pending application when this is necessary to distinguish the invention covered by such application from previous inventions; but to issue a patent for a thing which, in the judg. ment of the Office, is substantially the same in principle with something already known, simply because the applicant is willing to say by a disclaimer-for this, virtually, is what the disclaimer does say—that he will assume all risks as to the validity of the patent, is warranted neither by the statute requiring examinations nor by the policy upon which the statute is based. The effect of a disclaimer is entirely neutralized when, in its substance, it is contradictory of the claim and not merely explanatory of it.

In the present case, if the claim is correctly interpreted, it is suf ficiently answered by the reference. Any disclaimer, therefore, of the reference which does not carry with it a corresponding modification of the claim, is inconsistent with the claim, and cannot be permitted to control in passing upon the question of its patentability.

The decision of the Examiners-in-Chief is affirmed, and the patent asked for is refused.

FREDERICK NISHWITZ.-EX PARTE.

IN THE MATTER OF AN APPLICATION FOR THE EXTENSION OF LET. TERS PATENT NO. 19,377, FOR IMPROVEMENT IN HARVESTERS, GRANTED FEBRUARY 16, 1858, AND REISSUED A SECOND TIME, IN TWO DIVISIONS, NOS. 3,371 AND 3,372, APRIL 13, 1869.

(Decided February 12, 1872.)

Novelty of invention as involved in extension applications.

Certain claims of a patent which is offered for extension are found to be anticipated by a prior patent which is owned by parties who control the proposed extension: Held, that the patent may be extended upon ex-parte proofs that the latter patentee is in reality the prior inventor.

In such case, if the prior patent were held by parties adverse in interest to the extension sought, this should only be granted upon the filing of a disclaimer covering the anticipated claims-with the right to reassert the claims in a subsequent reissue application, filed with view to an interference.

DUNCAN, Acting Commissioner:

The only question calling for special notice in this case is that arising out of the requirement that the Commissioner of Patents, in considering an application for the extension of a patent, shall cause particular inquiry to be made as to "whether the invention or discovery was new and patentable when the original patent was granted."

Nishwitz's original patent was issued February 16, 1858, upon an application filed in the month of January preceding. The examiner reports that two claims of one division of the reissue, No. 3,372, are met by devices found in a prior patent granted to S. S. Allen, April 7, 1857. So far as one of these claims, at least, is concerned, there is no doubt that the examiner's position is correct. The claim, therefore, should never have been allowed to Nishwitz, except upon a judgment in his favor in a trial of priority with Allen. No such trial has ever been had.

Nishwitz, in presenting the present application, undertakes to carry the date of his invention as far back as the year 1853, which is some years prior to the time when Allen's application was filed in the Office; and the averments of the various affidavits by which this date is supported are so explicit and harmonious that, if it be proper to consider them at all, the invention must be regarded as having been fully reduced to practice in the year named.

Allen's patent has been extended; and the question now to be determined is whether the claims which on reissue were granted to Nishwitz in forgetfulness or disregard of Allen's right to an opportunity to prove priority of invention, shall now, as they are about to expire by the expiration of the term for which the original patent was granted, be extended for a further period of seven years upon the strength of the ex parte showing made by the applicant.

The only alternatives to this course are the following: First, the extension of the patent might be refused absolutely, on the ground that it includes features shown in an earlier patent, and of which Nishwitz bas never, in the mode contemplated by the statute, proved himself the first inventor. The ascertained value of the other features of the invention, however, is so great, and the inventor's diligence has been so commendable, and his success withal so slight, that this course would be adopted with reluctance and only in the absence of any justifiable alternative. The only remaining course would be to extend the patent upon a disclaimer being filed by the patentee, which should remove the objectionable claims. Such disclaimer might be filed with the understanding that on the grant of the extension the same claims might be reasserted in a subsequent reissue application, and then be put into interference with Allen's patent.