be permitted after the reception of evidence on the ground of ignorance of law or of the neglect of an attorney, and when permitted on any ground, at this stage of the proceedings, ample time is allowed to the adverse parties to contradict the amended allegations by additional proof.5 No defective preliminary statement ought to be received by the examiner ; but if received, and not objected to by the other contestants, the right to insist on its exclusion will be waived.6

§ 598. Interference Proceedings: Examination of Preliminary

Statements.

When the time for filing the preliminary statements has elapsed, such as have been filed are subjected to examination and are compared with the original applications on which the claims of the contestants rest. If it appears from this examination that the date of the filing of the earliest application is not anticipated by the dates fixed by the other parties for their own conception of the invention, priority is awarded to the earliest applicant.1 Where the preliminary statement of a later applicant fails to carry the date of his inventive act behind the date when earlier applications were filed, judgment is entered against him.2 Only in cases where the date claimed for his inventive act in the preliminary statement of one party anticipates the filing of an earlier application by some other party does the interference proceed further, since in these cases alone is the prima facie presumption of priority arising from the dates of filing the respective appli

That ignorance of the rules of the Patent Office or the carelessness of an attorney are no reasons for allowing an amendment after the evidence is in, see Guest v. Finch (1876), 10 O. G. 165.

That when the statement is amended after evidence taken the adverse party may be allowed, on motion, to take further evidence, see Moore v. Brown (1882), 22 O. G. 1882.

That a defective statement ought not to be received, but if it is the defect is waived unless objected to, see White v. Farmer (1874), 5 O. G. 338.

§ 598.1 That where an examination of the statements shows that no one is earlier than the first applicant judg ment will be rendered in his favor on notice to the other parties; otherwise a hearing will be held, see Booth v. Lyman (1880), 17 O. G. 393.

2 That unless the statement of a later applicant carries his date of conception beyond the date when the first applica tion was filed, judgment will go against him, see Huntley v. Smith (1880), 18 O. G. 795.

cations rebutted, and additional evidence rendered necessary in order to determine between the antagonistic claimants.

§ 599. Interference Proceedings: Taking Testimony.

If the interference proceeds, the time is then fixed by the examiner for the taking of the testimony by the several parties. A period is limited within which the latest applicant must complete his evidence in chief, followed by a period for the adverse party to finish his testimony in reply, and this by a third period for the rebutting evidence of the later applicant. Where there are more than two contestants their periods for taking testimony are so arranged that each shall have an opportunity to prove his own case against prior applicants, and to rebut their evidence when offered in reply, and also to answer that of later applicants. The time for taking evidence may be extended in favor of either party upon a motion disclosing under oath the reasons for his inability to obtain his evidence within the period prescribed, the names of the witnesses whose testimony he desires, the facts which he expects to prove by them, and the efforts he has made already to secure their earlier attendance. A failure to complete his testimony within the period assigned to any party is not permitted to delay the final hearing. The hearing may be postponed for sufficient reasons by the examiner in charge, but unless thus postponed a later applicant, whose evidence has been completed within the time prescribed, may insist upon a hearing and judgment, after that time has elapsed, upon the evidence as it then appears.

§ 600. Interference Proceedings: Burden of Proof: Evidence

Admissible.

The general rules of evidence apply in interference cases to the same extent and in the same manner as on similar issues

§ 599. That in an interference with a patent the time for taking evidence will not be made coincident with the later dates fixed in another interference with the same patent, unless there is some reason for it other than

that the facts are the same, see Keith v. Faure (1883), 25 O. G. 289.

2 That the courts are liberal in extending the time for taking testimony if the party has been diligent, see Osgood v. Badger (1888), 44 O. G. 1065.

in the courts.1 Priority of inventive act consists in the prior conception of the idea of means and the prior embodiment of this idea in some practically operative art or instrument, or reasonable diligence in perfecting such embodiment; and the successful claimant must establish this priority by a clear preponderance of evidence, though not necessarily beyond reasonable doubt.2 In order to do this he must not only overcome the presumptions against him arising out of earlier applications and patents on behalf of other parties, but must affirmatively establish his right to priority as against such parties themselves, by proofs sufficient to defeat their patents in the courts. Thus he must show that his conception of the in

§ 600. That the same rules of evidence apply in interference cases as in the courts, see Millward v. Barnes (1877), 11 O. G. 1060; Palm v. Behel (1876), 10 O. G. 701; Berry v. Stockwell (1876), 9 O. G. 404.

That the examiner of interferences has the exclusive right to decide as to the competency, construction, scope, and legal meaning of all foreign patents or other evidence, and to determine whether they cover the same invention as the one in interference, see Faure v. Bradley (1888), 44 O. G. 945.

2 That on an interference the party having the burden of proof must show that he first completed the invention, see McKnight v. Wagenen (1876), 9 O. G.

1161.

That a claimant against a patent has the burden of proof, see Donoughe v. Hubbard (1886), 27 Fed. Rep. 742; 35 O. G. 1561; Cushman v. Parham (1876), 9 O. G. 1108.

That where the prima facie proof arising from the patent is outbalanced by evidence of prior invention, the burden of proof shifts to the patentee, see Hazelip v. Richardson (1876), 10 O. G. 747.

That on interference the averment that an applicant is not an original inventor must be conclusively proved by

the party who alleges it, see Hockhausen v. Weston (1880), 18 O. G. 857.'

That an applicant in interference with a patent need not prove priority beyond reasonable doubt, see Fulgham v. Westcott (1879), 16 O. G. 1005.

That the assertion of an applicant that he "invented" at a certain date is of little weight against facts showing the contrary, see Slade v. Blair (1880), 17 O. G. 261.

That where one of two joint paten. tees applies for a sole patent he must overcome by evidence the presumption arising from his oath as joint-inventor, as well as the prima facie case presented by the prior patent, or judgment on the interference will be against him, see Lovrien v. Banister (1880), 18 O. G. 299.

8 That in an interference between an application and a patent, the applicant must offer such evidence of priority as would defeat the patent in the courts, see Gill v. Scott (1883), 23 O. G. 2511; Withington v. Locke (1877), 11 O. G. 417; Palm v. Behel (1876), 10 O. G. 701; Stoddard v. Perry (1874), 6 O. G. 33.

That if a junior inventor, using due diligence in reduction and application, obtains a patent and a senior inventor afterward applies, the latter must show entire freedom from laches or a patent

vention antedated that of every other claimant, and that at the date of their conceptions he had either reduced, or was using reasonable diligence in reducing, his own conception to successful practice. In proving his conception of the invention the claimant may present any evidence which tends to show that the idea of means was fully developed in his own mind at the date alleged. Verbal descriptions, drawings or sketches, models, other devices equivalent in principle or embracing all the features on which conflict now arises, and any other manifestation or embodiment of his idea sufficient for its complete expression may be offered to support his claim.5 I will be denied him and all doubts resolved in favor of the patentee, see Voelker v. Gray (1885), 30 O. G. 1091. That the first applicant is regarded as the first inventor till the contrary appears, see Starr v. Farmer (1883), 23 O. G. 2325, 2327.

That where an application is complete and duly filed the subsequent applicant must show that he invented, or conceived the idea and was diligently reducing to practice, before the prior application was filed, see Starr v. Farmer (1883), 23 O. G. 2325, 2327.

That if one of the applications in interference is a division of one previously filed, the date of the original will be regarded in determining on whom is the burden of proof, see Henderson v. Reese (1883), 25 O. G. 191.

That the successful claimant must show that he was the first to conceive and used reasonable diligence in reducing to practice, see Hammond v. Laird (1874), 7 O. G. 170.

That where two persons separately make the same invention the question is which is the first inventor, see Hall v. Johnson (1883), 23 O. G. 2411.

That where each one of two persons who united in reducing the invention to practice claims to be the inventor, the question is which conceived it, see Hall v. Johnson (1883), 23 O. G. 2411.

See also § 370-391 and notes, ante.

5 That on an interference the prima facie date of a patented invention is the date of filing the application on which the patent issues, though other records of the Patent Office may be consulted, see Booth v. Lyman (1880), 18 O. G. 132.

That the uncontradicted oath of the applicant that he made drawings of the invention at a certain time, if supported by one other credible witness, is sufficient though the drawings have been destroyed, see Smith v. Edson (1875), 7 O. G. 827.

That the production of sketches prepared for the occasion profits little except as illustrating other evidence, see McCullough v. Watkins (1875), 8 O. G. 1074.

That mere descriptions and destroyed drawings are not of much weight to show priority, see Ware v. Bullock (1874), 7 O. G. 39.

That a machine embracing all the features over which the interference contest has arisen may serve to show the date of the invention, though it lacks certain improvements found in pending applications, see Hockhausen v. Weston (1880), 18 O. G. 857.

That devices produced by the applicant which are equivalent in principle may fix the date of the invention, see Bird v. Walsh (1878), 14 O. G. 234.

That an abandoned application is not

In proving reduction to practice he must establish the existence of an operative art or instrument, capable of practical employment. Upon this point models, drawings, and descriptions have but little weight. Diligence in reducing to practice may be shown by any testimony applicable to the peculiar circumstances of the case. No claimant is allowed by evidence to carry the date of his conception of the invention behind the date assigned to it in the preliminary statement; and any substantial variation between such statement and the evidence on any point renders the evidence suspicious.7 Where the statement fixes its dates by belief and information the testimony may render them more certain considered in fixing the burden of proof, see Henderson v. Reese (1883), 25 O. G. 191.

That an abandoned experiment cannot be revived so as to secure priority on an interference, see Sheridan v. Latus (1883), 25 O. G. 501.

was completed, while in the other case there was only progress, however near that progress may have approximated to the end in view."

See also Gardner v. Dudley (1880), 17 O. G. 801; Halladie v. Paine (1877), 120. G. 1077; Sargent v. Burge (1877), 11 O. G. 1055.

That a patent is prima facie proof that the patentee had completed his invention, though its practical use is not shown, see Busha v. Phelps (1876), 9 O. G. 1010.

That the assertion of a party that he conceived the invention at a certain time amounts to very little unless he then completed it, see McCullough v. Watkins (1875), 8 O. G. 1074.

7 That the evidence must conform to the statement or it will be rejected, see Hovey v. Hufeland (1872), 2 O. G. 493.

See also §§ 380, 381 and notes, ante. 6 In Stover v. Clark (1877), 12 O. G. 188, Spear, Com.: (188) "The question in controversy is one capable of easy solution if the bearing of the Office in relation to interference proceedings, in which one of the parties is a patentee, is kept clearly in mind. In this class of cases the adverse applicant must show conclusively that prior to the time of the invention by the patentee he (the applicant) had fully reduced it to a form or condition capable of standing the test of actual practical use. An experimental reduction, the illustration of a theory by a model, will not suffice of itself to establish that completion which is alone regarded by the law as sufficient to impeach the title of the patentee. As was said in Coffin v. Ogden, 18 Wall. 124, 'If the thing were embryotic or inchoate; if it rested in speculation or experiment; if the process pursued for its development had failed to reach the point of consummation, it cannot avail to defeat a patent founded upon a discovery or invention which O. G. 964.

That any substantial variance between the statement and the evidence renders the evidence suspicious, see McCullough v. Watkins (1875), 8 O. G. 1074.

That the evidence as to the date of the invention need not agree with the statement, but must not show it to be earlier than the one therein alleged, see Connor v. Williams (1878), 15 O. G. 386; Walpuski v. Jacobsen (1876), 9