Page:Federal Reporter, 1st Series, Volume 1.djvu/319

PAGS V. HOLMES BDBGLAB ALABM TELEQBAFH CO. 311 �■combination with the compound electro-magnet reduced the size and expense of the machine, rendered it more simple and efficient, dispensed with the attendant, and thus brought it within the reach of almost every afflicted person requiring the remediai aid of electricity. The helix consista usually of two sizes of wire, the layers nearest the magnetic core being of large wire, say No. 16, and those exterior to them of fine wire, say No. 20 and upwards. The large wire is to be conneeted with a galvanio battery to induce magnetism in the core, and the shocks are obtained by contact with the ends of the fine wire. The helix a, thus formed, is secured to a base board by brass straps, b, b, and the extremities of the fine and large wires are let down through suitable holes in the base board, for the purpose of making ail the necessary con- nections underneath the board, out of sight, and give a neat ^ppearance to the instrument. The connections through whieh the galvanic circuit is completed, and the mode of breaking the circuit, are as foliows: The positive pôle of the battery is to be conneeted, we will suppose, with a bind- ing screw cup 1. At wire P, soldered to the lower part of this cup, passes under the base board to the point p', where it rises through the board to connect with one extremity of the large wire of the helix, the other extremity coming down through the board to connect with wire p'. The wire p' is soldered to the lower part of the pillar 2, and upon the top of this pillar is secured a metallic spring, s, which is in contact with a metallic point upon the lower end of set-screw s', and by this means in contact with pillar 3, f rom the lower end of which there passes a short wire, p', to the extremity, 4, of the wire d, d, surrounding the little electro-magnet e. The other ex- tremity, 5, descending through the board. is conneeted by a short wire, p*, with the lower end of biuding screw cup 6. The metallic circuit for the battery is thus completed, and the magnet e draws down the armature n attached to the end of spring s, and, breaking the contact between spring s and the point of the set-screw «', interrupts the galvanic circuit and produces the shock. The force of the spring 8 renews ■the contact with the set-screw, and the magnet e again acts, ��� �