that the descending brush roller crowds the driving wheels further apart, and increases the tension of the springs, I, I. That Plumb makes two independent statements-one in relation to the free motion of his wheels under downward pressure on the sweeper case, and the other concerning an increase of tension in springs, I, I-is made more evident by a comparison of the grammatical construction of his original application with that now forming part of the patent. In his original specification he stated, concerning his spring, that: "The spring, I, may be made from a single piece of metal. It is attached to the side of the case, as shown, passes over on a curve, and its lower end supports the journal for the driving wheel. This gives the wheel free play, when pressed both horizontal and perpendicular. The pulley, E, being above the center of wheels, W, W, the friction may be increased by pressing the sweeper on the carpet. The spring, I, may be varied in form, and may be constructed of any suitable material.”

In the amended specification, now the patent, he stated the second object of his invention to be "to journal the driving wheels to bearings having both vertical and lateral motion." He then said:

"The spring, I, may be made of one piece of metal, or of more; and the bearing of the wheel may be a flat piece of metal, or may be in the form of a yoke. The spring, I, may also be varied in length. The fastening of the spring to the case of the sweeper in one place only allows free motion of the wheel, and the center of the brush roller being above the centers of the driving wheels enables the operator to increase the friction between the wheels and the brush roller by merely pressing down on the sweeper. I prefer to attach this spring, I, to the side of the case, and have it pass over on a curve in the form shown in the drawings, but it may be varied in form and construction to suit the operator."

We quite agree with counsel for appellee in their contention that the quotation above contains two distinct statements, which are substantially the same as the two statements of the original specification above quoted. The first of these statements is substantially that wheels thus journaled in bearings attached to one end of a spring, the other end of which is attached to the side of the sweeper case, would permit the free motion of the wheels when pressure is brought to bear upon the case. The second statement is that, if the center of the brush-roller wheel be above the center of the driving wheels, downward pressure upon the case will crowd the driving wheels further apart by the descent of the brush roller, "and increase the friction between the wheels and the brush roller." We can but regard the specification as clearly explaining that the principle of his invention lies in the fact that his wheels are so journaled as to be capable of both vertical and lateral motion. This principle is an essential to every carpet sweeper having the advantage of "broom action," for broom action is nothing more nor less than the vertical motion of the wheels relative to a case carrying a brush attached to the case. That this claim does not include, as an element, a brush roller, is immaterial. The claim is not for a complete machine, but is limited to a specific improvement of a part of the mechanism of carpet sweepers, "having the brush roller operated by friction driving wheels." The specification fully describes such a machine, and points out all the elements necessary to con

struct it, and describes how the ingredients of his combination are to be arranged to co-operate with the other well-known parts to make a complete working carpet sweeper. A patent is addressed to those familiar with the art. A new and useful improvement upon an old machine is just as much the subject of patent rights as a new machine. All that the inventor is required to do is to point out distinctly the part he claims as new, so as to advise the public as to the extent of his invention, and what is thereby withdrawn from the public. Parks v. Booth, 102 U. S. 102; Seymour v. Osborne, 11 Wall. 516-541; Roberts v. Nail Co., 53 Fed. 916; 2 Rob. Pat. S$ 530-534. A distinction exists, though not always observed, between a statement of the mechanical functions of a machine, and the beneficial advantages, uses, or results due to that function, and contributing to the success of the invention. The function of a mechanism is its mode of action or operation proper to the structure, and does not ordinarily refer to the results, effects, or advantages of that appointed power of acting in a specific way. The patent statute recognizes this distinction, for it requires that a patentee shall state the "principle" of his machine,-meaning thereby its mode of operation, and nowhere mentions the beneficial effects, results, uses, or advantages. The principal function of Plumb's spring-supported sweeper case, when arranged to co-operate with the other ingredients of a carpet sweeper, is that, under downward pressure upon the sweeper case, the brush roller is lowered, and thus a varying pressure can be applied to the brush. This capacity of his contrivance he perceived and described when he referred to one of the effects of downward pressure as being an increase of driving friction. The lowered end of the brush is necessarily brought to bear more heavily on the boor. That this would be an advantage in the practical operation of a carpet sweeper would seem obvious. That it is of very great practical utility in the actual operation of his sweeper is established by the evidence, as well as by inspection of the exhibits. That Plumb did not see this advantage resulting from the function of his combination is hardly to be credited. This capacity of adjusting the brush for heavy or light sweeping is so obvious, so directly the appointed action of his mechanism, that whether he has described it specifically is not material. Neither the function, nor its advantage in the success of his sweeper, was a mere obscure property lurking in some accidental corner of the device. It lay upon the very surface, and was continuously in evidence when the sweeper was in operation. This combination resulted in an improved sweeper, capable of a new and beneficial use. He was the first to provide an elastic connection between the wheels and case. This new and most beneficial function is the immediate result of the idea of supporting a sweeper case by a spring connection on its wheels. He is entitled to this beneficial function of his invention, whether he then knew all its beneficial uses or not. McCormick Harvesting Mach. Co. v. C. Aultman & Co., 16 C. C. A. 259, 69 Fed. 371; Roberts v. Ryer, 91 U. S. 150; Brown v. District of Columbia, 130 U. S. 87-103, 9 Sup. Ct. 437:, Eames v. Andrews,

122 U. S. 40, 7 Sup. Ct. 1073; Miller v. Manufacturing Co., 151 U. S. 201, 14 Sup. Ct. 310; Stow v. Chicago, 104 U. S. 550; Tucker v. Spalding, 13 Wall. 453; Appleton Manuf'g Co. v. Star Manuf'g Co., 9 C. C. A. 42, 60 Fed. 411; Western Electric Co. v. Sperry Electric Co., 7 C. C. A. 174, 58 Fed. 186; Galt v. Parlin, 9 C. C. A. 49, 60 Fed. 422; Pfeifer v. Dixon-Woods Co., 14 U. S. App. 294, 295, 5 C. C. A. 148, 55 Fed. 390; Thompson Meter Co. v. National Meter Co., 12 C. C. A. 671, 65 Fed. 427. Patents cover the means employed to effect results. Neither an idea nor a function, nor any other abstraction, is patentable in a machine patent. Burr v. Duryee, 1 Wall. 570; Fuller v. Yentzer, 94 U. S. 288. In Eames v. Andrews, cited above, the patent was for an improved method of constructing artesian wells, and was for the process of drawing water from the earth by means of a driven well. Neither the scientific theory nor principle involved, and supposed to constitute the invention, were set forth either in the original or reissued patents. The comment of Judge Blatchford, who had tried the case upon the circuit, in relation to this defect in description, met with the approval of the supreme court. That great patent judge said:

"It may be that the inventor did not know what the scientific principle was, or that, knowing it, he omitted, from accident or design, to set it forth. That does not vitiate the patent. He sets forth the process or mode of operation which ends in the result, and the means for working out the process or mode of operation. The principle referred to is only the why and the wherefore. That is not required to be set forth. Under section 26 of the act of July 8, 1870 (16 Stat. 201), under which this reissue was granted, the specification contains a description of the invention, and of the 'manner and process of making, constructing, compounding, and using it,' in such terms as to enable any person skilled in the art to which it appertains to make, construct, compound, and use it; and, even regarding the case as one of a machine, the specification explains the principles of the machine, within the meaning of that section, although the scientific or physical principle on which the process acts when the pump is used with the air-tight tube is not explained. An inventor may be ignorant of the scientific principle, or he may think he knows it, and yet be uncertain, or he may be confident as to what it is, and others may think differently. All this is immaterial, if, by the specification, the thing to be done is so set forth that it can be reproduced."

Roberts v. Ryer, cited above, affords an interesting illustration of the scope of a patent which actually embodies a capability of use not perceived or described by the patentee. The patent involved was for an improvement in refrigerators, "whereby the whole of the contained air is kept in rotation, purification, desiccation, and refrigeration, with economy of ice." The apartments in the device pointed out for accomplishing this end were constructed so as to obtain the full benefit of the descending current of cold air in refrig erating the articles placed therein for that purpose. The defense was that the invention had been anticipated by a patent to one Lyman. Upon an examination it was found that both inventions adopted substantially the same means for cooling the air, and causing its circulation through the refrigerator. It appeared, however, that Lyman had so arranged his device as to use only the ascending air for the purposes of refrigeration, upon the wrongful supposi

1

tion that the greatest benefit was to be derived from that current. The complainant had seized upon this mistake, and, while adopting Lyman's method for confining and rotating the air, had arranged his refrigerating chamber so as to get the greatest benefit from the descending current. As to this the court said:

"It being then certain that Lyman contrived a machine which would produce the desired circulation, and could be used for refrigeration in the ascending current, it remains only to consider whether, if one desired to make use of the descending current for the same purpose, he could claim such a use as a new invention. It is no new invention to use an old machine for a new purpose. The inventor of a machine is entitled to the benefit of all the uses to which it can be put, no matter whether he had conceived the idea of the use or not. * * With both inventors the circulation, by means of an ascending and descending current, was the principal object to be attained. One considered the greatest benefit for the purpose of refrigeration was to be derived from the use of the descending current, while the other had his attention directed more particularly to the ascending current. They each had both, and could utilize both. It is no invention, therefore, to make use of one rather than the other."

In McCormick Harvesting Mach. Co. v. C. Aultman & Co., heretofore cited, this precise question as to whether it is always essential that a patentee shall describe the beneficial functions to be accomplished by the parts of his mechanism came before this court. It was a case of great importance, and received most careful attention. It was there said, concerning certain parts of Gorham's patent, that he had neither perceived nor described the beneficial effect resulting from certain segmental teeth in his improved grain binder, and that his patent should not be construed as including the invention subsequently asserted as within the scope of his patent, and dependent upon the functions of these teeth whose use was undescribed. Judge Taft, for the court, said, as to the effect on the patent of this defect in stating the results to be attained by these segmental teeth, that:

"It is not material that Gorham did not describe in full all the beneficial functions to be performed by the parts of his machine, if those functions are evident in the practical operation thereof, and are seen to contribute to the success of his device. Eames v. Andrews, 122 U. S. 40, 7 Sup. Ct. 1073. It is difficult to believe that a man of Gorham's inventive genius did not perceive the useful functions which the parts of his machine so well performed, even though he did not specifically mention them all."

In Pfeifer v. Dixon-Woods Co., cited above, the circuit court of appeals had a like question to deal with. Judge Shipman, in delivering the opinion of the court, said:

"The specification closely, and altogether too closely, adheres to mere mechanical features, and creates doubt as to whether Tondeur thoroughly understood his invention. It indicates that the patentee did not understand the philosophical principles which caused bis mechanism to produce an improved annealing. If he had known, they would have been alluded to in the patent; but an examination of the specification and its drawings leaves little doubt that the patentee meant, and that the specification means, to describe bars in such relation to each other that the glass is carried forward constantly in the same horizontal plane."

In the conclusion he added:

"He did not know, or he did not tell, why the new method would produce better results. He simply told how to construct a machine which carried

the glass through the leer on a level, and saved much breakage; but he ought not to lose the statutory benefits which would certainly belong to him if he had seen and described the philosophy of his machine accurately."

That the three sweepers made by appellant infringe the Plumb patent is a matter about which we have no doubt. Mechanically, they do not substantially differ from those held by Judge Brown to infringe in the Wetherbee Case. This was also the conclusion of Judge Severens, who, yielding to the interpretation placed by Judge Brown on the Plumb patent, found no reason for distinguishing between the devices which were made and sold by appellant, and those enjoined in the Wetherbee Case.

One of the infringing sweepers made by appellant is called the "Perfect." It is a four-wheeled sweeper. That is, in itself, no defense, if it is but a substantial duplication of Plumb's invention. At each side a straight spring rod passes through large holes in the ends of the case, this rod serving as the axle for a wheel at each end. Each rod is attached at its center to the top of the case by a bracket. Thus it is but a case spring-supported on its wheels, the spring differing only in form from that preferred by Plumb. There is little difference, mechanically, between appellant's "Star" and "Banner" sweepers and the "Perfect," already referred to. Each is spring-supported on its wheels. A straight metal rod, at each side of the case passes through large holes in the ends of the case, and carries a wheel at each end. These rods are controlled and pressed by a spring at each end of the case, so that the weight of the case is carried by these springs. None of these sweepers show any originality. They accomplish the same results attained by Plumb, by almost identically the same means. A mere change in the form of spring, or its place of attachment, by which vertical motion of the wheels relative to the case is obtained, is not invention. Our conclusion is that the decree of the circuit court must be affirmed.

On Rehearing.
(February 4, 1896.)

A petition for rehearing has been filed, which presents a question not definitely discussed in the opinion filed, although it received full consideration. Attention is called to the peculiar phraseology of the concluding line of the second claim of the patent, and it is said from this that "Plumb himself saw fit to limit his invention, whatever it is, upon the face of the claim itself, by the words 'when constructed as and for the purpose described.'' "The argument of counsel for the petitioner is that "this qualifying and limiting clause admits that Plumb did not have but one purpose. The claim is not for 'purposes' described, which would indicate that the mechanical combination of Plumb's claim might accomplish two or more purposes, but is limited to a single purpose"; "and," continues counsel, "what other purpose can be referred to, except the purpose of producing constant friction by means of his spring-pressure arrangement?" The first paragraph of Plumb's specification is in these words: "My invention relates to improvements in carpet sweepers having the brush rollers