This suit is founded on the second claim of letters patent of the United States No. 539,189, issued to Harry S. Pell, May 14, 1895, for an improvement in steam boilers. The application on which the patent was issued was filed June 5, 1894, but the record shows that an application for the same subject-matter, so far as regards the second claim, was filed December 22, 1893. The invention is shown to have gone into public use in the early part of 1892,—“somewhere between January and May of that year.” The first application was rejected January 27, 1894, and again March 31, 1.894; and on April 5, 1894, an amendment was filed erasing its first claim, the one covering the subject-matter in controversy. As a reason for erasing such claim, this amendment stated: “The subject-matter of claim 1 is thus taken out of this case, in order that it may he made the subject of another or divisional application.” On May 2, 1894, an interference was declared between the first application and another pending application; and on June 5,1894, the second application—the one in which the patent sued oh was issued—was filed, covering the' subject-matter now in controversy and other subject-matter. On these facts I hold that, so far as regards the defense of *81two years’ public use, the claim sued on relates back to the first application, and hence that the defense of public use is not made out. Godfrey v. Eames, 1 Wall. 317, 325; Smith v. Vulcanite Co., 93 U. S. 486, 500; Graham v. McCormick, 5 Ban. & A. 244, 248, 11 Fed. 859.
The claim sued on relates to supporting the lower mud drum of water-tube boilers. The specification describes, and the claim calls for, a combina!ion in which the water tubes are required to sustain “the weight of the mud drum and its contents, whereby provision is made for expansion and contraction of the drums and pipes.” Prior to the invention, the mud drum seems to have been supported rigidly on a chair or masonry, and some; patents show the elevated steam and water drums resting on the tubes or suspended from columns or girders. In these boilers (he expansion or contraction of the metal necessitated a corresponding disturbance or movement of the upper drums and upper ends of the tubes; and, as one witness says, "this lifting and bending caused a great many cracks to occur in tlie tubes, more especially in the front row,” "tlie tubes loosening in the tube sheets, the bending and breaking of the tubes, and the cracking of the brick settings.” In tlie patented boiler, however, it is the lower mud drum and lower ends of the tubes that are subjected to this disturbance or movement; and, these parts being free to move as required, this disturbance produces no injurious results. On the case as presented, I hold that changing the construction and operation as described amounted to a material and patentable difference over everything shown in the prior art. The boiler shown in the patent sued on has but a single mud drum; but: the specification states “that more than one may he used as desired,” and that “when more than one is used they may all be supported as above, or some of them supported in this way and others otherwise.” Tlie defendant’s boiler has three mud drums, at least one of which is suspended or sustained by the tubes connecting it to the elevated steam and water drums. I therefore hold that the defendant’s boiler is an infringement of the second claim of the patent sued on.