Reporter's Statement of the Case and agreed that the lawful owner of the money should eventually have it. The plaintiffs can not recover interest notwithstanding the money has been retained for a long period of years. The transaction as detailed precludes the contention that the money sued for was taken by the United States for a public use. The agreement effectually negatives such a contention. The acts of the parties were voluntary and in accord with an agreement. The plaintiffs are entitled to a judgment for $87,917.20. It is so ordered. WHALEY, Judge; WILLIAMS, Judge; LITTLETON, Judge; and GREEN, Judge, concur. THE MARLIN FIREARMS CORP. v. THE UNITED STATES [No. F-169. Decided April 6, 1936] On the Proofs Patents; improvements in aircraft machine guns; validity.-United States patent No. 1450653, for improvements in aircraft machine gun mechanism, held invalid for lack of invention in that it involved no more than mechanical skill. Invention; all elements of claim old; no new result.-Where all the elements of a patent claim were old and had been used in various mechanical arts as well as in the art to which the patent relates, and they accomplish no more than the aggregate of the old results, their use, even for a new purpose, would not be invention. Validity of claims; anticipation.-Where patent claims read upon preexisting structures in public use, they must be held invalid. The Reporter's statement of the case: Mr. W. H. Swenarton for the plaintiff. Mr. Alexander Holtzoff, with whom was Mr. Assistant Attorney General George C. Sweeney, for the defendant. Reporter's Statement of the Case An application for a patent by Carl G. Swebilius on June 11, 1918, was assigned to the Marlin Rockwell Corporation and by it assigned to plaintiff, The Marlin Firearms Corporation, on August 24, 1921. Louis H. Strouse and Eugene S. Bibb were appointed receivers of The Marlin Firearms Corporation July 13, 1923, and prosecute this case. Plaintiff sues to recover compensation in the amount of $400,000, more or less, with interest from April 3, 1923, the date on which patent #1450653 was issued on the abovementioned application, for alleged infringement and unauthorized use of the patented device on machine guns used on airplanes. The patent involved in the case covers a slide in the firing mechanism of the Browning aircraft machine gun, the purpose of which slide was the transmission of impulses of the trigger motor of the C. C. synchronizing gears to a sliding sear, which, in turn, controlled the firing pin which primed the cartridge. Swebilius conceived the alleged invention during 1918, as will be disclosed in more detail by the findings, while he was engaged as an employee of the Marlin Rockwell Corporation, which was manufacturing aircraft guns for the United States, in adapting the synchronizing gears of the Vickers aircraft machine gun to the Browning ground machine gun so as to equip it for use on airplanes. The questions now before the court relate to validity and infringement. The defendent interposes the defenses, first, that the patent is invalid in that it does not cover a patentable novelty; second, that if the device covered by the patent is in fact patentable, the United States is, under the circumstances, the equitable owner thereof; and third, that even if the Government is not the equitable owner, it has, on the facts, an implied license thereunder. The plaintiff denies these contentions and insists that the adaptation of the Browning machine gun for synchronized firing involved considerably more than the mere problem of transmitting motion from the trigger on the frame of the gun, having a path at right angle to the movement of the sear which released the firing pin, and that, therefore, the essence Reporter's Statement of the Case of the Swebilius invention of the patent in suit was not such as to be evident to or within the knowledge of the mechanic skilled in the art; that the patentee, Swebilius, was the first to employ in a synchronizing mechanism for automatic guns a reciprocating member, or slide, mounted on the breech bolt for reciprocation relative to the sear, and means to operate said slide, all for the purpose of transmitting impulses from the trigger motor to the firing pin of an automatic machine gun in such manner as only to effect the firing of the gun by such impulses when the same was completely breeched, and that none of the patents relied upon by the defendant as anticipating the patent in suit disclosed any such combination of such elements or of any equivalent thereof. The court having made the foregoing introductory statement, entered special findings of fact as follows: 1. A machine gun is a small caliber firearm in which either the gas pressure or the recoil of the gun barrel is utilized through appropriate mechanism to unlock the breech, eject the empty cartridge case, extract a fresh cartridge from a belt and feed it to the chamber, close and lock the breech and release the firing pin. These various movements are automatically accomplished and continue to take place as long as the trigger or release mechanism is held in firing position. The rate of operation of this mechanism or the rate of firing is dependent upon the inertia and extent of movement of the various moving parts and in general is in the neighborhood of from 800 to 1,200 rounds per minute. 2. In adapting machine guns for use on airplanes it is essential that the gun fire forwardly through the rotational plane of the propeller. A basic problem therefore arises in the development of suitable mechanism such as will permit the timing or synchronization of the shots relative to the rotation of the propeller in such manner that they will take place when the blades are out of the line of fire and thus avoid damage. One of the factors involved in this problem is that the rate of the firing of the machine gun per minute and the revolutions of the propeller per minute are generally never the same nor multiples of each other, the rate Reporter's Statement of the Case of revolutions of the propeller being generally faster than the rate of fire of a machine gun. 3. One solution of the problem of adapting machine guns to airplanes in such manner as to eliminate the danger of striking the propeller blades with the bullets was developed in England by Gogu Constantinesco. His solution consisted of a synchronizing gear mechanism which connected the airplane engine with the firing mechanism of the gun. The mechanism, which operated on the hydraulic principle, consisted of four main units: a generator unit operated by the engine and comprising a cam-operated piston; an oil line; a trigger motor, and a releasing mechanism unit. The generator unit transmitted pressure impulses through the oil line to the trigger motor and thence to the gun mechanism. The releasing mechanism unit was employed for the purpose of controlling or bypassing the pressure impulses and thus allowing the gunner to fire the gun at will and to stop firing when he so desired. The impulses transmitted to the trigger motor from the engine through the synchronizing gear were dependent upon the angular location of the operating cam relative to the propeller and the speed of the propeller. The gun was so designed that these impulses would not cause the release of the gear until the gun mechanism was in the position where the gun was breeched and ready for firing. This apparatus was generally known as the Constantinesco synchronizing gears or C. C. synchronizing gears. Constantinesco applied for United States patent on his invention on September 4, 1917, and letters patent #1372944 was issued to him thereon on March 29, 1921. A copy of this patent, defendant's exhibit 20, is by reference made a part of this finding. 4. Prior to August 1917, the British Government adapted a machine gun known as the Vickers for use on airplanes by connecting it to the engine with the Constantinesco or C. C. synchronizing gears and making certain necessary modifications in details of the firing mechanism of the machine gun. The Vickers aircraft gun with the C. C. synchronizing gear was used for synchronized firing from airplanes by Reporter's Statement of the Case the British, French, and the American Armies during the World War. 5. The Vickers machine gun referred to in finding 4 utilizes the energy of recoil to operate the mechanism of the gun. This energy operates to retract the breech bolt after the gun is fired. This movement of the breech bolt serves to eject the empty cartridge case and place a fresh cartridge in position for loading into the chamber. A recoil spring then functions to carry the barrel and breech mechanism forward into the firing position, sometimes referred to as the breeched or locked position. When the breech bolt is in the firing position, pressure on the trigger of the gun retracts a longitudinal trigger bar located in the cover of the breech bolt, the rear end of which bar is in an engagement with the trigger. The forward end of the trigger bar is in engagement with the "sear", which is a lever or cam having the function of holding the firing pin in its retracted position. Retraction of the trigger bar thus rotates the sear and causes release of the firing pin, which is then thrown forward by the firing-pin spring and primes or fires the cartridge. 6. In the summer of 1917 the War Department of the United States was engaged in investigating problems involved in the firing of machine guns from airplanes. In August 1917 representatives sent to Europe by the War Department obtained two British Vickers aircraft machine guns equipped with the Constantinesco synchronizing gears. About the first of September 1917 one of these Vickers guns equipped with the Constantinesco gears was delivered by the War Department to the plant of the Marlin Rockwell Corporation at New Haven, Connecticut. At the same time the War Department delivered to the Marlin Rockwell Corporation complete information regarding the problems arising in connection with synchronized firing. Army officers were detailed to the Marlin Rockwell plant to supervise work and furnish information to the Marlin Rockwell employees. 7. The Vickers aircraft gun with the Constantinesco synchronizing gear as furnished to the United States by the |