Opinion of the Court. issued to me October 14, 1879, and is not, therefore, saving as to the structural features by which it performs the further function of effecting the direct admission of air from the main air-pipe to the brake-cylinder, as presently to be described, claimed as of my present invention." Apparently, too, in consequence of the above letter of January 19, 1887, the patentee erased from his original specification the following sentence: "Further, while in the specific construction described and shown, the function of admitting air from the main pipe is performed by a valve separate from that which effects the preliminary admission of reservoir pressure to the cylinder, a modification in which the same office is performed by a valve integral with the main valve and formed by an extension thereof, would be included in and embody the essential operative features of my invention," and inserted in its place the following: "I am aware that a construction in which an always-open one-way passage' from the main airpipe to the brake-cylinder is uncovered by the piston of the triple-valve simultaneously with the opening of the passage from the auxiliary reservoir to the brake-cylinder, has been heretofore proposed, and such construction, which involves an operation different from that of my invention, I therefore hereby disclaim.” We agree with the defendant that this correspondence, and the specification as so amended, should be construed as reading the auxiliary valve into the claim, and as repelling the idea that this claim should be construed as one for a method or process. Language more explicit upon this subject could hardly have been employed. While it is true that no claim is formally made for the admission of train-pipe air directly to the brake-cylinder as a method or process, a construction is given by the complainants and the Circuit Court to the second claim which eliminates the mechanical features described, and one which could only be supported upon the theory that the claim was for a method or process. If the mechanism described by Westinghouse, and particularly the auxiliary valve, be not essential to the validity of the second claim, then it could only be supported Opinion of the Court. upon the theory that it was for the process of admitting trainpipe air directly to the brake-cylinder. 2. The first and fourth claims of this patent are as follows: "1. In a brake mechanism, the combination of a main airpipe, an auxiliary reservoir, a brake-cylinder, a triple-valve and an auxiliary valve device, actuated by the piston of the triple-valve and independent of the main valve thereof, for admitting air in the application of the brake directly from the main air-pipe to the brake-cylinder, substantially as set forth." "4. The combination, in a triple-valve device, of a case or chest, a piston fixed upon a stem and working in a chamber therein, a valve moving with the piston-stem and governing ports and passages in the case leading to connections with an auxiliary reservoir and a brake-cylinder and to the atmosphere, respectively, and an auxiliary valve actuated by the pistonstem and controlling communication between passages leading to connections with a main air-pipe and with the brakecylinder, respectively, substantially as set forth." These two claims are practically little more than different expressions of one and the same invention. In both of them there is a main air-pipe, an auxiliary reservoir, a brake-cylinder, a triple-valve and piston, described in the fourth claim as "fixed upon a stem and working in a chamber" in a case or chest, and an auxiliary valve; and in the fourth claim also a case or chest, which contains the whole device and is immaterial. In both of these claims an auxiliary valve is named as an element. In the first it is described as "actuated by the piston of the triple-valve and independent of the main valve thereof; and in the fourth as "actuated by the piston-stem and controlling communication between passages leading to connections with the main air-pipe and with the brake-cylinder." To what liberality of construction these claims are entitled depends to a certain extent upon the character of the invention, and whether it is what is termed in ordinary parlance a "pioneer." This word, although used somewhat loosely, is commonly understood to denote a patent covering a function VOL. CLXX-36 Opinion of the Court. never before performed, a wholly novel device, or one of such novelty and importance as to mark a distinct step in the progress of the art, as distinguished from a mere improvement or perfection of what had gone before. Most conspicuous examples of such patents are: The one to Howe of the sewing machine; to Morse of the electrical telegraph; and to Bell of the telephone. The record in this case would indicate that the same honorable appellation might be safely bestowed upon the original air-brake of Westinghouse, and perhaps also upon his automatic brake. In view of the fact that the invention in this case was never put into successful operation, and was to a limited extent anticipated by the Boyden patent of 1883, it is perhaps an unwarrantable extension of the term to speak of it as a "pioneer," although the principle involved subsequently and through improvements upon this invention became one of great value to the public. The fact that this invention was first in the line of those which resulted in placing it within the power of an engineer, running a long train, to stop in about half the time and half the distance within which any similar train had stopped, is certainly deserving of recognition, and entitles the patent to a liberality of construction which would not be accorded to an ordinary improvement upon prior devices. At the same time, as hereinafter observed, this liberality must be exercised in subordination to the general principle above stated that the function of a machine cannot be patented, and, hence, that the fact that the defendants' machine performs the same function is not conclusive that it is an infringement. The device made use of by the defendants is exhibited in patents No. 481,134 and No. 481,135, both dated August 16, 1892, and both of which were granted after the commencement of this suit. There are two forms of this patent, one of which, illustrated in patent No. 481,135, is here given on the opposite page in its three positions of release (20), service application (21), and quick action (22). In this device there is found a main air-pipe, an auxiliary reservoir, a brake-cylinder, a triple, or rather a quadruple, valve and piston (29) with three ports; first, for the admission of air from the train-pipe to the brake-cylinder through the feeding-in valve 26; second, for the passage of air from the auxiliary reservoir to the brake-cylinder through the apertures i, j, k in the stem slide-valve 18; and, third, for the release of air from the brake-cylinder to the exhaust port by means of valve 17, colored green. Whether this device has an auxiliary valve or not is one of the main questions in the case, complainants' theory being that poppet-valve 22 is an auxiliary valve, while defendants' claim is that it is in reality the main valve. The operation of this device is best shown by the foregoing skeleton drawings. The auxiliary reservoirs are charged by air under pressure, Полловен Auxiliary Reservoir Opinion of the Court. entering from the train-pipe, raising and passing through the feeding-in valve piston 26, and flowing slowly into and through the passage A to the auxiliary reservoir, until such reservoir is filled. In this condition the brake-cylinder is emptied and opened to the atmosphere through the exhaust passage G. In order to apply the brakes gradually, so as to slacken speed or make an ordinary stop, air pressure in the train-pipe is reduced slightly (say from three to five pounds) by action of the engineer's valve, and the reduction of pressure on the right side of the piston 29 causes the piston to make what is termed a "preliminary traverse" to the position shown in diagram "Service Application." Such preliminary traverse pulls the stem slide-valve 18 to the right, and opens the apertures i, j and k, (one of these apertures being to the right and the other to the left of valve 22,) and through these apertures air rushes from the auxiliary reservoir to the brake-cylinder; but the poppet-valve 22 still remains upon its seat. If quick action be required, the pressure in the train-pipe is suddenly lowered to the extent of fifteen or twenty pounds, and the travelling piston 29, instead of making a preliminary traverse to the intermediate position shown in the "Service Application," makes a full traverse to the extreme right, the effect of which is that the valve 22 is pulled off its seat by the collar M, and a large passage is opened to the brake-cylinder under the valve 22 and around the stem 18. The result is, as shown in the last diagram, that not only does the air in the auxiliary reservoir escape in full volume to the brake-cylinder, but air from the train-pipe rushes directly to the brake-cylinder through the large passage F into the chamber C and under valve 22. The argument of the defendants in this connection is that, in this device, there is no auxiliary valve or by-passage, but the quick-action result is effected simply by proportioning the ports and passages of the old triple-valve, and using a fixed partition, 9, to divide the piston chamber D from the mainvalve chamber C; that it is this partition which produces the quick action, and that such partition is not a valve, nor the mechanical equivalent of a valve, but merely a metal ring |