use of two flumes carrying the current of air from the fan, only one of which brought the air into contact with the heater. It speaks of a use of a means for controlling temperature of the air passing to each egg compartment, by mixing in proper proportions the flow of air from the two flumes. The existence of such a double conduit is not corroborated by any witness or any document, and is explicitly denied by Lieber, testifying in behalf of petitioner in the Stone case, made a part of the present record, and by Hastings. Peabody, who installed the electrical equipment, and Hickox, who prepared a contemporary written description of the incubator, make no mention of it. Drawings showing a single passageway carrying the current of air to the egg stacks were identified as accurate by Hastings, Lieber and Peabody. We conclude that, whatever experimental proposals or installations may have been made, the incubator was used with a single air passage above the egg compartments.

All the witnesses agree that the incubator was commercially operated during the hatching seasons of 1912 and 1913, and that it hatched different batches of eggs placed in it, with varying success. The hatches of the eggs furnished by some customers were failures. Others were successful. One of petitioner's witnesses testified that the hatches never exceeded 50%. Lieber estimated that 50% was the average, with some people getting none and others getting 80%. Hastings, who in the Canadian suit testified that the average was 40%, stated that some settings ran up to 70%. There is no testimony of any mechanical failure of the incubator after the initial trials of it, as a result of which an electric blower was substituted for the fan of lesser power. In 1912, Hastings departed for Texas, where he started another incubator. After operating the incubator through another hatching season, Lieber, his financial backer, abandoned the enterprise.

As with the Brooklyn incubator, the critical issue is whether that in Muskogee was used with eggs in staged incubation in the manner of the Smith claim. It is established beyond doubt that eggs in different stages were in process of incubation there at the same time. The incubator was used in large measure for "custom hatching." At frequent intervals, patrons brought their eggs in relatively small quantities to be placed in the incubator for hatching, and received at the end of the hatching period their share of the newly hatched chicks.

The testimony of Hastings that staged incubation was employed in the Muskogee structure is corroborated by this course of business and by the contemporaneous statements and brief filed with his patent application. He testified that eggs of different stages were sometimes, though not always, placed in the same compartment of the incubator. The Poultry Culture article of February, 1912, states, after describing the use of the fan-propelled current of heated air in the incubator: "eggs at all stages can be placed in the same trays of the Hastings hatchery, with little or no injury. Mr. Hastings hatched several thousand eggs under such conditions in his Brooklyn plant last year."

Petitioner stresses the point that in the Muskogee incubator, the stacks of egg trays were concededly placed in separate compartments, with openings at the top having slide doors which could be used like a valve for regulating the volume of air flowing into each compartment. Hastings testified that the slide doors were used to cut down the supply of air when there were few or no eggs in a compartment and that they were left open when the compartment was substantially full of eggs. Petitioner points to this and to some testimony by Hastings and Lieber that the slide doors could be used to regulate the temperature in each compartment through control of the

volume of air passing through them, and to testimony by Lieber that the eggs, as received, were first placed in one compartment and then at intervals, as other eggs came in, were moved from one compartment to another, and that the doors were used to control variations of temperature in the different compartments.

From this the inference is drawn that only eggs of the same stage were placed in any one compartment, and from the inference it is argued that they were not set in staged incubation. But even if the inference is correct, it establishes only that a special method or device to guide and control the air current was used, not that staged incubation was wanting. The presence or absence of a device for controlling the current of air within the incubator is no part of the Smith claim. Our opinions in Smith v. Snow, supra, and Waxham v. Smith, supra, were careful to point out that infringement of the method could not be avoided by using it in conjunction with such a device. The presence of the device in the Muskogee incubator did not foreclose anticipation if the method was used. Since the circulating current of air passed repeatedly into the compartments in the Muskogee structure and came in contact with the heating pipe and with the eggs in the several stacks of trays, the tendency of the operation was to equalize the temperature and to carry heat units from the more advanced to the less advanced eggs. This is the method of the patent and it was employed in the Muskogee structure whether the trays of eggs of different stages were placed in the same or different compartments.

The patent was sustained in the Snow and Waxham cases, supra, only by establishing that neither the arrangement of the eggs, nor the particular order in which the propelled current should reach the eggs, nor the manner in which it was guided or controlled, is part of the

patent claimed. It was this construction of the claim which gave a new significance to the Hastings incubators, different from any recognized by previous decisions. The petitioner, having sought and obtained a broad construction of his claim, cannot now narrow it so as to avoid anticipation by showing that the claimed method was used in a particular form of structure not claimed. It was the method thus defined which Hastings used, regardless of the particular structure which he devised to guide and control the current of air in his incubator, or the order in which it came into contact with the heater and eggs of different stages. It is immaterial that his structure for using the method was neither the best possible nor as skilfully designed or used as that later employed by Smith. Pickering v. McCullough, 104 U. S. 310, 319; cf. Telephone Cases, 126 U. S. 1, 531, 536.

In view of this conclusion it is unimportant whether Hastings used the method in his Brooklyn incubator. But we think the testimony of its use there is sufficiently corroborated. His statement in "The Dollar Hen," already quoted, published before the Brooklyn structure was erected, shows clearly that he contemplated the continuous operation of an incubator with the eggs set in staged incubation so that they would be hatched for deliveries once or twice a week, by a procedure substantially that of the Smith claim. The circumstances attending the Brooklyn use, which called for the setting of eggs at frequent intervals in an incubator of large capacity, the structure exhibited in Hastings' patent application, the subsequent course of the application in the Patent Office, and finally the renewed effort at Muskogee embodying the same principles, although with an immaterial variation in structure, and the fact that both incubators functioned, are convincing evidence that Hastings knew and used in appropriate combination, both in

Brooklyn and in Muskogee, the essential elements of the Smith claim. They support the heavy burden of persuasion which rests upon one who seeks to negative novelty in a patent by showing prior use. See Radio Corporation v. Radio Engineering Laboratories, 293 U. S. 1, 7, and cases cited.

Petitioner urges, and we have considered, numerous other objections to the sufficiency of proof of the Hastings prior use. The only one calling for any comment is the suggestion that the Brooklyn and Muskogee enterprises were not commercially successful. Commercial success may turn the scale when invention is in doubt, Paramount Publix Corp. v. American Tri-Ergon Corp., 294 U. S. 464, 474; DeForest Radio Co. v. General Electric Co., supra, 685, and the want of it may, in some circumstances, be evidence of want of operative success. But here Hastings by the use of a method which we have sustained as an invention, Smith v. Snow, supra, has attained the particular results described by the patent. He knew the method and used it in a device capable of employing it. In such circumstances want of commercial success, which the record suggests may have been due to lack of technical and business skill, is not an indication that there was no prior use.

Upon the records now before us we must conclude, as did the Supreme Court of Canada upon a similar record (Footnote 1, supra), that Hastings antedated Smith. The Smith method was "known or used by others in this country before his invention or discovery thereof." 35 U. S. C., § 31.

Affirmed.

MR. JUSTICE VAN DEVANTER took no part in the consideration or decision of these cases.