Page:Federal Reporter, 1st Series, Volume 1.djvu/315

 PAGE V. HOLMES BXJRGLAB ALAEM TKLKGBAPH 00. 307. �broken with great rapidity. An adjusting or set-screw may be placed on a suitable support over this end, after the man- ner of the last named vibrating circuit-breaker, so as to regu- late the extent of the vibrations. The weight of this end, or what may be denominated its retractile force, may also be regulated by a small movable weight placed on or over this half of the armature, after the manner shown in figure 10. This circuit-breaker is introduced into the circuit of the primary coil in the same way as the revolving armature. A more simple form of vibrating armature is shown in figure 9, in whieh the armature n vibrates to and from the electro-mag- net w M, in a direction parallel to itself. It is attached to a light brass spring s, fastened to pillar 2. This spring passes through an opening in the yoke y on the top of pillar 3. At ^ is a tip or small disk of platinum, soldered to the spring, which is in contact with the platinum point on the lower end of the set-screw s', passing down through the top of the yoke. Set-screw s' is accompanied with a tightening nut «'. This set-screw regulates the proximity of the armature to the mag- net, and, to some extent, the tension of the spring and the rapidity of its vibrations. It will be seen, however, that the regulation or adjustment is imperfect, for, as the spring is pressed down towards the magnet, the armature is brought nearer to the magnet, and, as the attractive force increases more rapidly with the diminution of the distance between the armature and the magnet than does the force of the spring increase, the adjustment is, in a measure, defective. If, now, the magnet d d he connected with the battery and charged, and the circuit with the battery is made by the cur- rent passing ûp pillar 2, thence into spring s, thence into set- screw s' and pillar 3, and thence through the wires of the electro-magnet back to the battery, the magnet will draw down the armature, and with it spring s, and thus break the circuit, by puUing the platinum disk away from the plat- inum point on the lower end of set-screw s*. On breaking the circuit the magnet loses its power, and the spring rises and completes the circuit again, the magnet is again charged and the armature drawn down and breaks the circuit again, ��� �