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

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. 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 y y, 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.

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. which is made in the shape of a cross, in the usual manner, is placed upon the lower die Fig. 1.

The blank,

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 òblique 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:

Opinion of the Court.

Putting the blank into that shape is what the specification refers to when it speaks of "the straightening of the body," and "forming the sharp corners."

The defendants make shackle blanks by dies, under letters patent No. 106,225, granted to Willis B. Smith, August 9, 1870. Fig. 3 of that patent is a plan view of the blank which the dies forge, and Fig. 4 is an end view of the blank. In

these figures, b, b, are the ears; d is the clip; f is the shaft; g is the body of the blank; h, h, are the corners at the junction of the ears and the body; H is the whole blank. The corners h, h, are formed at right angles to each other. The specification says, that the blank H is then placed in a trimming die, and the surplus metal which projects from its edges is removed; and that the blank is then heated, and the oblique portions of

the body, g, are bent, so as to throw the ears, b, b, upward, in the form shown in Fig. 5, in which operation the corners, h, h,