1897, and declared it to be a rule that an invention dates not from the time of its full and definite conception but from the time it is first reduced to practice. "The authorities," says the court, seem to be conclusive upon the point that a conception evidenced by disclosure and drawings does not constitute an invention under the patent laws." The illogicalness of this position is justified by the court on a basis of public advantage.

But the court states two qualifications to this rule. The first is that an application for a patent will be treated as a `sort of constructive reduction to practice; that is to say, invention may date from the filing of the application even though the concept has never actually been reduced to practice. As the court puts it, "From these established and seemingly contradictory principles of the patent law, first, that an invention in order to be patentable must be reduced to practice, and, second, that, under the statutes, reduction to practice is not essential either before or after the grant of a patent, it follows that there must be some stage of an invention when it must be presumed as a matter of law that the inventor has reduced his invention to practice; and that stage is presumed to have been reached when he has done all that he is required to do to obtain a valid patent, namely, when he has filed a complete and allowable application; and hence the Patent Office has adopted the rule that the filing of such an application is constructive reduction to practice, and the federal courts have adopted the rule that Such an application is conclusive evidence that the patentee has made his invention—that is, reduced his invention to practice -at least as early as that date."

The second qualification is that the date of invention may be carried clear back to the time of the conception, even withcut any reduction to practice, if the inventor has used due diligence in attempting to reduce it to practice. "It is conceded," says the court, "that a patentee who has used 'reasonable diligence in adapting and perfecting' his invention can carry the date back to his drawings and disclosure."178b

178b The right of an admittedly prior conceptor was declared to be lost because of his unreasonable delay in reducing his concept to practice, and

A working model not necessary. An actual working model of the invention is not required. In the case of Loom Co. v. Higgins1 179 the court quite precisely said, “An invention relating to machinery may be exhibited either in a drawing or in a model, so as to lay the foundation of a claim to priority, if it be sufficiently plain to enable those skilled in the art to understand it."

Identification of knowledge. When a patentee has succeeded in demonstrating to the court's satisfaction that he really did have a certain definite idea at the time alleged, there then arises the very different question whether this idea is the same one actually embodied in the patent. While it is frequently left as a fact for the jury, and is in one sense a question of fact, it is truly a question of psychological fact, a matter of conclusion, reached by the operation of the judicial mind upon the patent of a subsequent conceptor of the same idea was upheld, in One-Piece Lens Co. v. Bisight Co., 246 Fed. 450.

"Now Reno is in this dilemma: if his disclosure was complete in October, 1900, he was not reasonably diligent in waiting until the end of December, 1902, to file his application; if he was reasonably diligent it was because he needed for the completion of his conception the intervening two years, and he does not antedate Stone & Brenchard. He himself suggests no reason for the delay, but the necessity of engineering study, and that did not interfere with an application if he had really fully conceived the invention. . . . He makes no claim that poverty or sickness stood in his way, nor that he was too engrossed with independent affairs, assuming that such would be any excuse. For these reasons his date of invention must be in my judgment that of his application." United Tunnel Co. v. Interborough, etc. Co., 207 Fed. 561, 569.

"Diligence is of the essence of a proper relation between the conception and the reduction to practice of an invention, and must consist of a degree of effort that can fairly be characterized as 'substantially one continuous act.'" Twentieth Century Co. v. Loew Co., 243 Fed. 373, 384.

"As the evidence shows that both inventors used 'reasonable dilligence in adopting and perfecting' their inventions by reducing them to practice, each can carry the date of his invention back to the date of his conception and disclosure . . . and the one who first conceived and disclosed his invention and with reasonable diligence connected his conception with its reduction to practice is the 'original and first inventor' under the statutes, without regard to which of the two first completed the reduction to practice." Evans v. Associated, etc. Co., 241 Fed. 252. 179 105 U. S. 580.

the perceptible actualities presented. Much the same precedents may be used, in arriving at a particular conclusion upon the evidence presented, as are used for guidance in determining whether certain prior knowledge constitutes anticipation. The question is really the same. In the ascertainment of anticipation the inquiry is, whether the knowledge proved to have existed, prior to the patent, is sufficiently definite and similar to constitute substantially the same thing. When the date of invention is in issue, the inquiry, in the particular phase under discussion is, whether the concept proved to have existed prior to the application for the patent is sufficiently definite and similar enough, in essence, to that of the patent to be substantially the same invention as that patented. The fact that any change from the original idea whose date is proved, and that covered by the patent, was made by the originator of ́the idea himself does not matter. If the change has been of the essence, has required inventive genius, the date of the new invention can not be carried back to that of the original. "The invention or discovery relied upon as a defense must have been complete, and capable of producing the result sought to be accomplished; . . . If the thing were embryonic or inchoat; if it rested in speculation or experiment; if the process pursued for its development had failed to reach the point of consummation, it can not avail to defeat [or to protect] a patent founded upon a discovery or invention which was completed, while in the other case there was only progress, however near that progress may have approximated the end in view. The law requires not conjecture but certainty. If the question relates to a machine, the conception must have been clothed in substantial forms which demonstrate at once its practical efficiency and materiality."180 And again,181 "Although prior unsuccessful experiments in part suggested the construction which the patentee adopted and perfected, this fact will not defeat [nor protect] the patent.' Neither would incomplete, inchoate 180 Coffin v. Ogden, 18 Wall. 120, 124.

182

181 Whittlesey v. Ames, 13 Fed. 893, syl.

182 Agawam Co. v. Jordan, 7 Wall. 583, 602. "The settled rule of law is that whoever first perfects a machine is entitled to the patent, and is

ideas of the invention suffice to carry the date of invention back of the date of application for the patent, against a showing of knowledge between the dates of the experiments and that of the application.

183

As illustrative of the effect of collateral circumstances upon proof of the date of invention, is the case, just referred to, of Loom Co. v. Higgins.184 Here, one Davis professed to have invented a device, prior to Webster's production of it. The court rejected this claim, for lack of evidence, and said incidentally, "Another circumstance seems to us as having much weight in this connection. It was found that the loom No. 50, and the Sterling loom, when completed in 1871, worked with wonderful success; sometimes as many as sixty yards being woven on one loom in ten hours. If Davis was the inventor of the wire motion applied to these looms, why did he never apply for a patent for it? He was already a patentee of a different and inferior apparatus. He knew all about the method of going about to get a patent. He belonged to a profession which is generally alive to the advantages of a patent-right. On the hypothesis of his being the real inventor his conduct is inexplicable.'

the real inventor, although others may have previously had the idea and made some experiments toward putting it into practice. He is the inventor and is entitled to the patent who first brought the machine to perfection and made it capable of useful operation."

183 For further authorities see the discussion of the inquiry as to what constitutes sufficient knowledge to anticipate. Westinghouse Elec. Co. v. Beacon Lamp Co., 95 Fed. 462; The Wood-paper Pat., 90 U. S. 566, 594; Allis v. Buckstaff, 13 Fed. 879; Hillard v. Fisher-Book-Typewriter Co., 159 Fed. 439, 441, “Statements in a prior application relied upon to prove anticipation must be so clear and explicit that those skilled in the art will have no difficulty in ascertaining their meaning"; Lincoln Iron Works v. M'Whirter Co., 142 Fed. 967.

184 105 U. S. 580.

CHAPTER III

UTILITY

The statute provides that an invention to be patentable must not only be new but must be "useful" also:185 It does not, however, say just how much usefulness there shall be, nor does it indicate what is meant by "useful." The interpretation is left open to the courts. It is clear from the decisions that "useful" is not used in the sense of "usable," If it were in this sense, the patent office would be encumbered with great many fewer absolutely impractical "paper" inventions. There are, for instance, of record, in the neighborhood of 700 patents for various types of explosion turbines and parts thereof. Yet manufacturers are unanimous in saying that a usabļe, practicable, explosion turbine can not be built, so far as present knowledge of metals goes. It is evident therefore that these 700 patents are not for "usable" devices; yet no one would deny that they are valid patents.

The requirement of usefulness has in fact been restricted to the purpose for which the device is intended, and has not been connected with the actual operation of the device. In an early case it was contended strongly that the requirement should properly be applied to the device itself as well as to the purpose of it. The literal form of the statute possibly bears out this assertion, that a "useful art, machine, manufacture or composition of matter" is one which can be used. But the generally held judicial opinion was voiced in that case by Mr. Justice Story as follows:186 "To entitle the plaintiff to a verdict, he must establish, that his machine is a new and use

185 § 4886-"any new and useful art, machine, manufacture or composition of matter"; § 4893—"if on such examination it shall appear . . that the same (the invention) is sufficiently useful and important, the Commissioner shall issue a patent therefore."

186 Lowell v. Lewis, 1 Mason 182.