
9 F.2d 306 (1925)
A. SCHRADER'S SONS, INC.,
v.
WEIN SALES CORPORATION.
No. 361.
Circuit Court of Appeals, Second Circuit.
June 13, 1925.
*307 William H. Davis, James L. Steuart, and R. Morton Adams, all of New York City, for appellant.
Eugene V. Myers, Arthur C. Fraser, and William A. Redding, all of New York City, for appellee.
Before ROGERS, HOUGH, and HAND, Circuit Judges.
HAND, Circuit Judge (after stating the facts as above).
We do not consider whether the plaintiff's evidence was sufficient to carry the date of invention back of Turner's sealing dates in April and May, 1907. The appellant has assigned no error on that point, and did not argue it before us. We assume, therefore, that Twitchell antedated Turner, and the validity of the patent depends upon whether the evidence showed that the use was public. We observe at the outset that the use must have occurred before October 9, 1906; the application having been filed two years from that date. On this issue of public use the defendant has the burden. Loew Filter Co. v. German American Filter Co., 107 F. 949, 47 C. C. A. 94 (C. A. 6); Maast Foos & Co. v. Dempster Mill Mfg. Co., 82 F. 327, 27 C. C. A. 191 (C. C. A. 8). The classic exposition of the doctrine *308 is Mr. Justice Brown's in the Barbed Wire Patent Co. Case, 143 U. S. 275, 12 S. Ct. 443, 36 L. Ed. 154, there being no distinction in this regard between prior use by another and by the inventor himself.
The proof, though scanty, is that no one was allowed in Twitchell's factory but himself and his assistants, who had not, however, apparently been pledged to secrecy. Had the factory been a large one, to which many employees had access, such a pledge was necessary; but this was the case of a man working confessedly upon an experiment in leather tires, and meaning to keep his work secret. Before October 9, 1906, he had but one employee, Stine, who was aware of the experimental nature of the business. Considering that the whole work was experimental, and that only these two had access to it, we think that it was unnecessary to exact from Stine a formal pledge of secrecy. It was implicit in the situation. We, of course, recognize that the use may be public, although concealed by the nature of the invention itself. Egbert v. Lippmann, 104 U. S. 333, 26 L. Ed. 755; Hall v. MacNeale, 107 U. S. 90, 2 S. Ct. 73, 27 L. Ed. 367. Again, we agree that the use of a single specimen, even in a factory and in the presence only of the employees, may be public. Brush v. Condit (C. C.) 20 F. 826, affirmed 132 U. S. 39, 10 S. Ct. 1, 33 L. Ed. 251; Smith, etc., Co. v. Sprague, 123 U. S. 249, 8 S. Ct. 122, 31 L. Ed. 141; Perkins v. Nashua (C. C.) 2 F. 451; Bliss Co. v. So. Can Co. (D. C.) 251 F. 903. But in these cases the factory was open for many employees to come and go, a distinction we regard as critical. A majority of the court does not believe that the defendant has shown the use to have been public.
However that may be, we all agree that, whether public or not, it was experimental. Confessedly Twitchell was engaged in experiment. The answer is that the experiments concerned only the making of leather tires, and that the gauge had passed the stage of experiment, though the main business had not. We agree that in law the distinction is good. Thompson-Houston Electric Co. v. Lorain Steel Co., 117 F. 249, 54 C. C. A. 281 (C. C. A. 2). Furthermore, we recognize that, once the use be shown to be public, the plaintiff must establish by convincing proof that it was experimental.
In spite of both considerations, we are satisfied that the use during the period in question was only experimental. Twitchell expressly so testified, and Stine corroborated him. He is further corroborated by the circumstances. The time was short finally to settle the practicability of such a device. The gauge was of a makeshift character, cobbled together with a wooden anvil, a rubber tube, and an ordinary spring gauge with a dial. To suppose that during the first four or five weeks such a device had finally demonstrated its sufficiency seems to us inherently unlikely. Especially is this true when it was made only for incidental use, in testing the products which were the chief object of the experiments. Twitchell's attention was primarily devoted, not to the accessories of his shop, but to the larger projects in which he was engaged. His definite conclusion about the gauge would come from its occasional use as part of his working kit. We must distinguish between such a case and one where he was avowedly trying to invent the tool itself. Cases like Mfg. Co. v. Sprague, 123 U. S. 249, 8 S. Ct. 122, 31 L. Ed. 141, and National Phonograph Co. v. Lambert Co., 142 F. 164, 73 C. C. A. 382 (C. C. A. 7), concerned much longer periods, one of over four years and the other of nine. They have little application to the situation at bar.
Finally, we think that the claims are infringed. The issue here is whether the defendant's gauge bar is "spring-held." It was later found much more convenient not to attach the gauge to the piston head, so that it need not return with the spring. We agree that the phrase "spring-held" most naturally refers to the express disclosure, but we are not disposed to treat the claims literally. The result achieved by the patentee was to show the movement of the piston head under air pressure, and this the defendant's gauge does by precisely the same means. The return of the gauge with the spring was not one of the objects of the invention, and it was quite unnecessary to its operation. It seems to us that under the doctrine of equivalents the defendant's gauge accomplished substantially the same result in substantially the same way. The new gauge is an improvement, but it contains all the useful elements of the original invention.
Judgment affirmed.
