Reporter's Statement of the Case 10. The use of water in submarine fuel tanks, called a "hydraulic follow-up or compensating system," was practiced on United States submarines prior to Lantz's earliest date. In this system the tanks were always kept "solid," i. e., full of liquid (oil when the ship was fully fueled), and as oil was withdrawn, water was forced in to take its place. The oil to be used was pumped or forced by the compensating water into elevated tanks whence it flowed by gravity to the engines. 11. Prior to Lantz's earliest date the pressure on the compensating water was about 15 lbs. per sq. in. and the water was obtained from the engine circulating system. In the V-2 and V-3 boats, the pressure was reduced to about 8 lbs. per sq. in. by the use of a head box, or elevated tank, from which the water flowed by gravity. Unlike the outboard tanks, in which the compensating water pressure increases as the submarine submerges and is approximately equal to the sea pressure at the submarine's depth, the pressure within the inboard tanks of the submarines charged to infringe is substantially unaffected by diving, and remains substantially constant at the value for which the system is designed. 12. By 1929 it was observed that the tank tops of the submarines were leaking oil at the seams into the interior of the ship as a result of vibration and the strains of operating in rough seas and the pressure on the oil in the tanks. Commander Robert A. Smith at that time suggested that this condition could be remedied by reducing the pressure within the tanks to approximately atmospheric value and secured permission to make such change. He thereupon inserted in the compensating water-lines of the S-44 three commercial Mason regulating valves, these being so arranged and connected as to reduce the pressure upon the compensating water in the fuel tanks to substantially atmospheric value. These were inserted in the compensating line to each of the three groups of tanks. 13. Mason regulating valves are well known articles of commerce, and old prior to Lantz's earliest date, and their construction and operation were well understood by those skilled in the art. Reporter's Statement of the Case Such typical valves are shown and described in the catalogue of the Mason Regulator Company filed in the Library of Congress on June 2, 1913, defendant's exhibit 15, page 128 of which is herewith reproduced: The description of said valve appearing on page 129 of said catalogue is as follows: Mason No. 55 Steam Pump Pressure Regulators comprise a balanced valve, J-4, directly connected by means of the stem, J-11, to the diaphragm, J-18. The discharge pressure is connected at J-22, and acts on the upper side of the diaphragm. This pressure is resisted by the spring, J-16, which is adjusted to the desired pressure by the adjusting screw, J-12. When used as a reducing valve, it is installed with the diaphragm chamber, J-20, down, and the pipe connection from J-22 is run upwards and connected either to the line itself beyond the valve or to some other convenient point in the reduced pressure system. 14. The typical Mason regulator valve referred to in these findings comprises a valve positioned between the inlet and outlet lines, and the valve element is movable longitudinally off its seat to establish communication between inlet and outlet lines. The valve is urged toward open position by a spring J-16, and toward closed position by a diaphragm J-18, subjected to the pressure existing on the outlet side of the system. The diaphragm chamber J-20 is connected to the tank by a so-called pilot line, which does not transfer liquid, but serves only to maintain the pressure within the diaphragm chamber equal to that in the tank. 15. In operation, the tension of the spring tending to open the valve is adjusted by screw J-12 until the valve opens when the outlet (or tank) pressure drops below the desired value. This permits the pressure to build up on the outlet side until the force exerted by the diaphragm due to pressure on the outlet side forces the valve closed against the spring pressure. Such valves, when properly constructed and installed, will maintain the outlet pressure almost exactly constant, irrespective of fluctuations of inlet pressure within the limits for which they are designed. 16. Although the Mason valves used in the S-44 were not "balanced" (a "balanced" valve being one which has four 109870-39-c.c.-vol. 87- -22 Reporter's Statement of the Case operating faces, two exposed to inlet pressure and two to outlet pressure and facing oppositely, so that the pressures on the faces cancel each other) as were those on the V-2 and V-3, the outlet pressure was substantially independent of fluctuation of input pressure, change in outlet pressure being only 3164ths of change of inlet pressure. 17. The valve of the Lantz patent is not constructed like the Mason regulator valve, and operates on a different principle. The Lantz valve permits the outlet (or tank) pressure always to be equal to the inlet pressure minus a fixed amount, which amount is determined by the design and construction of the valve. 18. Prior to the filing date of the Lantz patent there were available to the public the following patents and publication: Mason Regulator Company Catalogue No. 60, copyrighted 1913 (defendant's exhibit 15). None of the foregoing prior art is of record in the prosecution of the Lantz application in the United States Patent Office. 19. No one of the prior art patents and publication discloses the system disclosed in the Lantz patent, in that no one of them discloses an outboard fuel tank subject to vary |