A Book of Exposition

by Homer Heath Nugent

Fig. 4.

After the line of matrices and spaces has served its purpose, it is raised from the casting position and moved to the right, as shown by the dotted lines and arrows in Fig. 2. The teeth in the upper ends of the matrices are engaged with a toothed bar R, known as the second elevator. This elevator swings upward, as shown by dotted lines, carrying the matrices to the level of the upper end of the magazine, and leaving the spaces or justifiers behind to be transferred to their magazine H.

The distributing mechanism consists essentially of a fixed bar T, lying in a horizontal position above the upper end of the magazine, and having along its lower edge, as shown in Fig. 2, horizontal teeth to engage the teeth in the upper end of the matrices and hold them in suspension. The teeth of the matrix for each letter differ in number or arrangement, or both, from the teeth of matrices bearing other letters, and the teeth on the lower edge of the distributor bar are correspondingly varied in arrangement at different points in the length of the bar. (See Fig. 2.)

The matrices are moved forward into engagement with the distributor bar and also into engagement with the threads of horizontal screws U, which are extended parallel with the distributor bar and constantly rotated so that they cause the matrices to travel one after another along the distributor and over the mouths of the channels in the magazines. Each matrix is held in suspension until it arrives over its proper channel, where for the first time its teeth bear such relation to those of the bar that it is released and permitted to fall into the magazine.

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.

Fig. 5.