The speed of the machine, which is commonly from four to five thousand ems per hour, but which has reached ten thousand and upward in competitive trials, is due to the fact that the matrices pursue a circulatory course, leaving the magazine at the lower end, passing thence to the line and to the casting mechanism, and finally returning to the top of the magazine.  This permits the composition of one line, the casting of another, and the distribution of a third to proceed simultaneously.

ASSEMBLING AND KEYBOARD MECHANISMS

The matrices pass through the magazine by gravity.  Their release is effected by mechanisms shown in Figs. 5 and 6, which are vertical sections through the magazine, the keyboard, and intermediate connections.  Under each channel of the magazine, there is an escapement B, consisting of a small lever rocking at its centre on a horizontal pivot, and carrying at its opposite ends two dogs or pawls b, b, which are projected up alternately into the magazine by the motion of the lever.  The key-rod C, suspended from the rear end of the escapement B, tends to hold the lower pawl b in an elevated position, as shown in Fig. 5, so that it engages under the upper ear of the foremost matrix to prevent its escape.

[Illustration:  Fig. 5.]

When the escapement B is rocked, it withdraws the lower pawl b, as shown in Fig. 6, at the same time raising the upper pawl, so that it engages and momentarily arrests the next matrix.  As soon as the first matrix has escaped, the escapement resumes its original position, the upper pawl falling, while the lower one rises so as to hold the second matrix, which assumes the position previously occupied by the one released.

[Illustration:  Fig. 6.]

Thus it is that the alternate rising and falling of the two escapement pawls permits the matrices to escape one at a time.  It is evident that the escapements could be operated directly by rods connected with the finger-keys, but this direct connection is objectionable because of the labor required on the part of the operator, and the danger that the keys may not be fully depressed.  Moreover, it is essential that the escapements should act individually with moderate speed to the end that the matrices may be properly engaged and disengaged by the pawls.  For these reasons, and to secure easy and uniform action of the parts, the mechanism shown in Figs. 5 and 6 is introduced between the finger-keys and escapements.  The vertical rods C, which actuate the escapements, are guided in the main frame, and each is urged downward by a spring c.  Each rod C terminates directly over one end of a rising and falling yoke-bar c2, turning on a pivot c3 at the opposite end.  Each of the yokes c2 is slotted vertically to admit an eccentric c4 turning on a pivot therein.