Sloan Filter Co. v. Portland Gold Min. Co.

HOOK, Circuit Judge,

after stating the case as above, delivered the opinion of the court.

The result of the application of the common skill and experience of a mechanic, which comes from the habitual and intelligent practice of his calling, to the correction of some slight defect in a machine or combination, or to a new arrangement or grouping of its parts, tending to make it more effective for the accomplishment of the obj ect for which it was designed, not involving a substantial discovery, nor constituting an addition to our knowledge of the art, is not within the protection of the patent laws. Gates Iron Works v. Fraser, 153 U. S. 332, 14 Sup. Ct. 883, 38 L. Ed. 734; Florsheim v. Schilling, 137 U. S. 64, 11 Sup. Ct. 20, 34 L. Ed. 574; Hollister v. Benedict Mfg. Co., 113 U. S. 59, 5 Sup. Ct. 717, 28 L. Ed. 901; Atlantic Works v. Brady, 107 U. S. 192, 2 Sup. Ct. 225, 27 L. Ed. 438; Dunbar v. Meyers, 94 U. S. 187, 24 L. Ed. 34; Hotchkiss v. Greenwood, 11 How. 267, 13 L. Ed. 683; Adams Electric Ry. Co. v. Lindell Ry. Co., 77 Fed. 432, 23 C. C. A. 223; Tiemann v. Kraatz, 85 Fed. 437, 29 C. C. A. 257.

The mere use of known equivalents for some of the elements of prior structures; the substitution for one material of another known to possess the same qualities, though not to the same degree; the mere carrying forward or more extended application of the original idea, involving a change only in form, proportions, or degree, and resulting in the doing of the same work in the same way and by substantially the same means — is not patentable, even though better results are secured; and this is the case, although what preceded rests alone in public knowledge and use, and not upon patent. Market Street Cable Ry. Co. v. Rowley, 155 U. S. 621, 15 Sup. Ct. 224, 39 L. Ed. 284; Wright v. Yuengling, 155 U. S. 47, 15 Sup. Ct. 1, 39 L. Ed. 64; Adams v. Stamping Co., 141 U. S. 539, 12 Sup. Ct. 66, 35 L. Ed. 849; Burt v. Evory, 133 U. S. 349, 10 Sup. Ct. 394, 33 L. Ed. 647; Brown v. District of Columbia, 130 U. S. 87, 9 Sup. Ct. 437, 32 L. Ed. 863; Crouch v. Roemer, 103 U. S. 797, 26 L. Ed. 426; Roberts v. Ryer, 91 U. S. 150, 23 L. Ed. 267; Smith v. Nichols, 21 Wall. 115, 22 L. Ed. 566; Hicks v. Kelsey, 18 Wall. 670, 21 L. Ed. 852; National Hollow Brake-Beam Co. v. Interchangeable, etc., Co., 106 Fed. 693, 45 C. C. A. 544; National Folding Box & Paper Co. v. Lithographic Co., 81 Fed. 395, 26 C. C. A. 448.

The doctrine of equivalents applies to patents for a combination, although the measure of its effect in the particular case depends upon the position of the patent in the art to which it relates. National Hollow Brake-Beam Co. v. Interchangeable, etc., Co., supra.

The mortising of timbers to prevent them from shifting and sliding, and thereby to secure rigidity and stability of the framework, and the use of wooden wedges for a similar purpose, was nothing more than would naturally occur to any carpenter who understood his business. Mortising and the use of wedges are as old as carpentry itself; and, when the contemplated use of the structure precluded the employment of nails or other metallic fastenings, the method adopted by Sloan was but a simple and obvious expedient. It was not invention.

In the use of sheets of perforated lead as a flooring and as a filtering medium in a barrel filter there was on the part of Sloan neither discovery nor such ingenuity of adaptation as entitled him to a patent. No new function was performed by those elements of his filter, acting either singly or in co-operation with the others; nor was there a new method of performing an old one. The use of lead, and its especial value in the interior of barrel filters, were old in the art. In the floor of Sloan’s filter the perforated sheets of lead performed in the same way the precise function theretofore performed by the lead-covered steel sheets, and by the perforated hardwood boards, either with or without the superimposed lead sheets; and as a filtering medium their precise function was theretofore performed by asbestos cloth, slotted sheet lead, and woven lead in combination with asbestos. They were, respectively, substitutes for each other, being well known to possess like qualities and to operate in the same way to produce the same results. The sheets of lead, in their relation to the other elements of the combination and their co-operative action, were the mere equivalents of those in prior use. There was no change of function, operation, or result. This seems to have been recognized, in part at least, by Sloan himself. He says in his specifications:

“A woven lead fabric is believed to be a novel filtering medium in this connection, and, while the best results will accrue from its use, the asbestos cloth is a valuable substitute therefor; but quite desirable results will accrue from the use of properly perforated sheet lead.”

In fact, Sloan never used a woven lead fabric as a filtering medium, but in practice confined himself to the perforated sheets, while the use of asbestos cloth was common and extensive before he had any knowledge whatever of barrel filters.

In the briefs of both parties it is said that the real operation of the sheeted lead filtering medium was to support the coarser particles of ore above it, and to cause them to act as the true filtering medium. In other words, the pulp resting upon the diaphragm was the real filtering medium, and the operation of the perforated lead was merely to retard or prevent its passage during the process of filtration. If this view be correct, and there is support for it in the testimony, it would occur to any one that the office of a retarding medium could clearly be as well performed by any durable material susceptible of stable perforation and capable of resistance to the action of chlorine gas.

Were we to exclude from consideration the lead-covered steel plates, the slotted sheets of lead, and the woven lead in combination with asbestos, upon the ground, as claimed, that they were experiments and had been discarded for better devices, there would still remain the flooring of corrugated and perforated hardwood, with and without the cover of lead sheets, and the filtering medium of asbestos, both in combination with perforated sheets of lead and without it, all of which appear in the prior art, and to have been operated successfully before Sloan’s invention. We would, therefore, be brought to no different conclusion.

The decree of the Circuit Court is affirmed.