after making the foregoing' statement, delivered the opinion of flie court.
While not prepared, in view of the authorities, to sanction the proposition that the infringer of a patent may escape liability by showing that the legal owner is engaged in a supposed unlawful combination or trust, we do not consider the point. We think the dismissal of the bill justified upon other ground. There is in the record before us proof of many adjudications in different circuit courts whereby the Reed patent was declared valid, but in one instance only (Reed v. Smith, 40 Fed. 882) has the opinion of the court been reported. Those adjudications, except the first, it is fair to assume, were governed largely by the well-known rule of comity by which one federal court follows the ruling of another, especially in patent cases, and are therefore not entitled to the weight of so many independent judgments. In Reed v. Smith, upon a showing of newly-discovered evidence, some of which appears in this record, a 3'ehearing was granied, and the case was disposed of without going to a final decree. The reported opinion, however, is no less valuable on that account, and in some respects it is helpful in the present discussion. Upon a comparison of the claims of the patent as originally made with those allowed, the conclusion is there declared, in which we fully concur, (hat it did not involve; invention, or anything more than mechanical skill, to adapt the adjustment of the rake teeth shown in the Paddock patent to the teeth of a spring harrow. “While the adoption of this device,” it is said, “was undoubtedly a happy thought and appears to have been the om; thing necessary to insure the popularity and general use of the spring-tooth harrow, we do not think it belongs to that class of conceptions which the law dignifies by the name of ‘invention ;’ ” and accordingly it was held “that the clip, which lies at the foundation of the plaintiffs’ patent, is limited to a curved clip with biting edges, designed to hold the tooth rigidly in its seat.” .It is clear, therefore, that Reed, though the specification of Ms patent shows that he would have had it understood differently, was in no sense “a pioneer in the art of adjusting curved teeth longitudinally upon their seats.” It was permitted to him finally to claim only an improved form of clip for fastening the teeth in plací1. Paddock’s device showed for that purpose simply a clamping hook, located at the middle of a curved and grooved seat; but evidently it was not beyond the powers- of ordinary skill and knowledge; to devise or adapt or adopt other forms equally effective. In the language of Reed’s specification, “other forms will readily suggest themselves.” It is not to be said judicially, of coarse, that: in such a field, narrow as it was, invention •was impossible; but it is very clear that if (here was novelty in this “curved clip with biting edges’’ it was at most a very slight and formal advance in the art beyond what was known, or was of very easy production. If, for instance, the single hook in the Paddock device, when applied to a harrow, failed to hold the tooth firmly, what was there to do more readily than to employ two hooks at the ends of the seat, either with or without a third one at the middle, and in what respect would the two at the ends have differed mechan-*240ieally from the ends or edges of the clip in Reed’s patent? Plainly such a use of two hooks in lieu of one could not be invention, and it will hardly be said to have been beyond mechanical skill to devise a firm connection between the two hooks so as' to require the use of but one bolt to move them or to hold them in place. An equally obvious expedient was a curved clamp, corresponding more or less nearly in length with the seat'and in curvature with the tooth to which it was to be applied. Indeed, it is apparent on the evidence before us, which in part is the newly-discovered evidence for, the admission of which the decree in Reed v. Smith was opened, that such a curved clamp, even with biting edges, was in use upon the hay-rakes of Paddock long before Reed had constructed his device. Whether Paddock is worthy of belief when he says that the curve of his clamp was intentionally made such that only its ends would have a transverse bearing upon the tooth, is immaterial. A sample of the clamp, produced in evidence by the appellant, is clearly of that construction, whether it was made so intentionally, or, as it is insisted and perhaps has been testified, by “the natural shrinkage of the metal, which always takes place at the projecting points first.” To constitute anticipation of a later patent it is enough that such a construction had been in well-established use, whether it originated in design or by accident. It may be that the curvature illustrated by the sample of clamp in evidence varies so little from the curve of the tooth that when pressed down the ends would not touch the tooth with a biting edge as distinctly as in some of the forms illustrated in the Reed patent, but it is to be observed that neither in the specification nor claims of that patent is the word “biting,” or its equivalent, to be found, though it is often used with emphasis in the' briefs, and some of the clips illustrated, instead of biting edges, have distinctly rounded ends, whose force in holding the tooth in place under conditions of equal pressure must always be in proportion to the degree of possible friction, which in turn must be in proportion to the area of the surfaces brought into instant contact. It is to be observed further that, if the curvature of a tooth and its seat be the same, the application of a clamp of Avhatever form will not affect the curve of the tooth, but if the seat be flat, and longer than the clamp, as, for instance, it is shown to be in the Miller patent, the tooth under pressure of the clamp, will lose curvature, and approach a straight line. If the clamp and tooth be of the same normal curvature, the application of pressure will produce between them a crescent-shaped space, and so the clamp, which along its whole length at first touched the tooth, at last has a transverse bearing only at its ends. In other words, upon a seat which is fiat, or is less curved than its tooth, any clamp which is' shorter than the seat, and has a curvature not less than that of the tooth, becomes in use, “a curved clip with biting edges,” and, if it were not an anticipation, would be an infringement of the patent in suit.
Upon these considerations, and others of like character which might be suggested, we are clear that this patent is void of invention, and on that ground the decree below is affirmed.