Opinion of the Court.

June 25, 1867, for an "improvement in the manufacture of blanks for carriage thill shackles." The main defence to the suit is non-infringement. The Circuit Court, after a hearing and two rehearings, dismissed the bill, holding that infringement had not been proved. 7 Fed. Rep. 816. The plaintiff has appealed.

A history of the state of the art, and of the progress of invention in making shackle blanks, will conduce to a determination of the questions involved. A carriage thill shackle is a device by which the thills of a carriage are hinged to the axle. The finished shackle is a horizontal plate, with a pair of vertical ears rising therefrom, one at each end of the back. The cockeye on the end of the thill is received between the ears, and a bolt passing through the ears and the cockeye secures the parts. The flat back or body part of the article is forged with a projection at each side, forming what is commonly called the clip," by which the article is secured to the axle. In forming the shackle, it is necessary that the outside corners, where the ears join the back, should be sharp, full and square, to obtain a good bearing on the axle, or the article will not be salable. The old style of shackle was of this shape. It was formed by

bending up the two ears from a piece of metal of equal thickness, and the outer corners became round, and the bearing on the axle was not firm and true. It was desirable to obtain in some way a reservoir or surplus of metal, which could be utilized, in the bending, by being thrown out into or remaining in the corners, to make them full and square on the outside. To

Opinion of the Court.

attain this result, one James P. Thorp made an invention for which he obtained letters patent No. 28,114, granted May 1, 1860, which were reissued to his assignees, H. D. Smith and others, as No. 2,362, September 18, 1866. Thorp's blank was of the following shape: The two projections on the bottom of

the blank were intended to furnish sufficient metal to make the outer corners of the shackle square and sharp, when the ears were bent in the direction indicated by the arrows. The projections were at the places where the arms joined the body. Thorp's patent showed a die for making the blank, constructed with recesses or cavities to form the projections, and stated that, after the arms were bent up, the blank, instead of being of the old form, Fig. 6, with rounded corners, a, a, thus:

Opinion of the Court.

would be of the form of Fig. 7, with square or right-angled corners, a, a, thus:

the blank being stronger at the junction of the arms and body, and the expansion of the metal, in bending the arm, being compensated for by a diagonal contraction of the metal, which operated to prevent the destruction of the cohesion of the particles of the metal, and the consequent weakening of the blank at the parts where it was bent.

The next step is shown in letters patent No. 65,641, granted June 11, 1867, to Leander Burns and Josiah Wilcox, on the invention of Burns. That patent shows, in Fig. 7, an upper die M, and a lower die N, and the blank made between them, with square corners, L, L thus:

Fig. 7 is a transverse vertical section taken in the plane of the line yy, in Fig. 6. Fig. 6 is a face view of the lower die, N, and shows also the blank after it is acted on by the dies. The specification states, that, if the arms of the blank are bent up at right angles, in a direction towards each other, perfect square corners will be left at L, L, with the metal through those corners and the other parts of a uniform thickness.

Opinion of the Court.

Fig. 6.

N

y

Then followed the patent to the plaintiff, the specification and drawings of which are as follows:

"This invention relates to the construction of carriage shaft shackles from solid blanks, and to the shape of the dies for forming the same, so that, with the least amount of labor and power, the said shackle may be gradually formed into the required shape. In the annexed drawings this invention is illustrated. Fig. 1 is a vertical sectional view of a shackle blank, showing it between the dies. Fig. 2 is a top or plan view of a shackle blank, as the same is formed by the dies. Similar letters of reference indicate like parts. The blank, which is made in the shape of a cross, in the usual manner, is placed upon the lower die Fig. 1.

Fig. 2.

A, and the upper die B is then forced down upon it, whereby the arms a, a, of the blank are bent

into an oblique direction, and the body, b, is curved, as shown in the figure. The portion of the blank where the arms join

Opinion of the Court.

the body is rounded, as shown, on both the inside as well as on the outside, the straightening of the body of the shackle pushing out sufficient material for forming the sharp corners, without having any hindersome and impracticable projections. The dies are formed so as to give the blank the required shape. This process of forming shackle blanks has proved, by practice, to be the most expeditious and simple yet performed, as it requires the least amount of machinery, and forms each part of the shackle with just the required amount and thickness of metal for completing the article."

The claims, two in number, are these: "1. The carriage shaft shackle blank, so formed between dies that the body b of the blank is curved, substantially as herein shown and described. 2. The dies A and B, for making the said blank, when so constructed and arranged as to form the rounded corners and the curved body of the said blank, substantially as herein shown and described."

The plaintiff, according to his description, takes a blank in the form of a cross, and, by dies of proper shape, bends the arms of the blank into an oblique direction, and the body into a curved form, the result being, that the parts where the arms join the body are rounded on the outside as well as the inside; and when, subsequently, the curved body is straightened, there will be in it sufficient metal to form sharp outside corners, by being pushed out into them. The plaintiff's patent stops with the curved blank shown in Fig. 1 of his drawings. That blank is, in practice, afterwards formed, by other dies, into the following shape:

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