delivered the opinion of the Court:

Since there is such a sharp issue of fact in this case, it is apparent that the surrounding circumstances and the inherent probability or improbability of the testimony must have a material bearing upon the outcome. Beals v. Finkenbiner, 12 App. D. C. 23. And where it clearly appears that a witness has wilfully testified falsely as to a given point, his entire testimony is entitled to little- consideration, for “courts are bound by principles of law, morality, and justice, to apply the maxim, Falsus in uno, falsus in omnibus." Alexander v. Blackman, 26 App. D. C. 541; Campbell v. State, 3 Kan. 498; Dell v. Oppenheimer, 9 Neb. 457, 4 N. W. 51; Stoffer v. State, 15 Ohio St. 56, 86 Am. Dec. 470. The theory upon which this rule is founded is not that a witness who has wilfully perjured himself is incapable of speaking the truth as to other facts, but rather that the motive that prompted him to commit perjury in one part of his testimony may lead him to support it by falsifying other parts. In other words, courts have found it unsafe to base an award upon the testimony of such a witness.

In the present case we have two men of high character, occupying positions of trust and responsibility, and possessing special skill in the art to which this invention relates. To deny their claim to the invention we must find that they deliberately entered into a conspiracy to deprive their subordinate, Mr. Riley, of the fruits of his genius. There is no half-way ground, for deliberate perjury rests on one side or the other. That Mr. Riley has testified falsely in one material respect is overwhelm^ ingly established; for, instead of being absent from his duties for over a month at the time the drawings for the invention forming the subject-matter of the second interference were being prepared, he was there practically every day. While there is less direct evidence that he saw these drawings than as to his being present during the time of their preparation, we think he *495is clearly discredited as to this point. In other words, we entertain no doubt whatever that he saw these drawings while they were in process of evolution. We must, therefore, scrutinize all of his testimony with great care.

We think the evidence of Emerson and Yoerg satisfactorily shows that the conversation at Carlings café occurred on Sunday, .December 20, 1908, and that the general features of the invention of this interference were there disclosed. Admittedly, Air. Riley had not then disclosed any part of the invention to them or either of them. That an interview took place between Air. Yoerg and ALr. Riley on the next morning even Air. Riley himself admits. Both the evidence and circumstances tend to show that Air. Yoerg then disclosed the general features of the invention to Air. Riley, and directed him to work out the details on paper. This it was Air. Riley’s duty to do. Air. Riley’s testimony at this point is very improbable, and, to our minds, unbelievable. He says he then had in his possession the small tracing (his Exhibit I)), and that for some unexplained reason he took this tracing to the office on the 23d, and showed it to both .Mr. Emerson and Air. Yoerg. He does not explain why, if the elaborate drawings in his sketch book which completely covered both the invention of this and of the companion interference were then in existence, he made no mention whatever of them. He does say that previously he had withheld information from Emerson and Yoerg because of his fear that they would appropriate his invention. Just why there was less danger of their appropriating it if disclosed by means of the small tracing than there would have been had he disclosed it by means of his sketch-hook drawings, he does not explain. Nor does he explain, or attempt to explain, why he did not show or make known this sketch book to his own counsel when this application was being prepared.

Air. Riley attempts to explain his failure to include the subject-matter of the second interference in his first application, by the statement that he supposed the first application was sufficiently broad to cover both forms. But it is very significant that this draftsman, whose knowledge of superheaters was the*496orotical, and not practical, should have originally devised both forms of the invention. It will be borne in mind how the second form came to be devised by Emerson and Yoerg. Mr. Riley has attempted to prove too much. It is unbelievable that back in January, 1901, he conceived both forms of this invention and in February of that year, on a single day or within two or three days at most, according to his own testimony, made the elaborate drawings in his sketch book covering both forms. We are convinced that the drawings of the invention of this and of the companion interference in this sketch book were not made until a time subsequent to the disclosure of Emerson and Yoerg.

The testimony of the witness Whealon we are unable to accept. The other witnesses for Mr. Riley, with the possible exception of Mr. Crawford, to whom we shall presently refer, would hardly have distinguished one drawing from another, and their testimony, therefore, is of little importance here. That the testimony of Mr. Crawford might have been seasonably obtained is apparent, we think, and we therefore are not prepared to say that the Patent Office tribunals erred in suppressing it. It may be suggested, however, that even if that testimony should be considered it would not change the result. That Mr. Crawford was a partisan of Mr. Riley’s is apparent. He left the employ of the Great Northern road December 31, 1901, and his testimony was given June 13, 1911. In view of the fact that the drafting room was the place where drawings for the various parts of locomotive engines were made, and that various types of superheaters were developed, it is not strange that this witness should have had some conversation with Mr. Riley on the subject of superheaters. The testimony of the witness, however, is altogether too vague to convince us that Mr. Riley then disclosed to him this invention. Nor do we think the witness ever saw the drawings covering- this invention in the Riley sketch book at the time he testifies he did.

An attempt'has been made to discredit Mr. Yoerg in connection with the calculation of heating surfaces which he made on the yellow slips of paper introduced by Mr. Riley as exhibits. It is contended that these calculations were. made with ref*497erenee to Riley’s Exhibit D. Mr. Yoerg testifies that they were made in January, while he was developing the second form of superheater, and that they were preliminary in character. Mr. Ross, the draftsman, remembers that calculations were made and that they were made on similar paper. Of course, he could not definitely identify these particular sheets. Moreover, it is possible that these calculations were made by Mr. Yoerg with reference to the largo tracing of December 31st and either while that tracing was under way or at its completion. Admittedly this shows substantially the same structure that is shown in the small Riley Exhibit D tracing. In view' of the fact that the calculations were preliminary in character, and that the sheets of paper upon which they were made were cast aside by Mr. Yoerg, we do not think it would have been at all strange had he been mistaken in his testimony as to just when the calculations were made. At all events, since Mr. Riley has been so badly discredited as to this Exhibit D and otherwise, we accept Mr. Yoerg’s statement that he did not see that Exhibit.

On the whole case, we are clearly of the opinion that the awmrd of priority should have been in favor of Emerson and Yoerg. The decision of the Commissioner will therefore be reversed. Reversed.