At the left side of the box cut a slot through the wood, so that a lever and hook may project and work up and down. The end of this lever is provided with a hook on which a receiver may be hung, as shown in Fig. 13, and the inside mechanism is arranged as shown at Fig. 14. A is an angle-piece of brass or copper, which acts as a bracket and which is screwed fast to the inside of the box. B is the lever and hook, which is cut from a strip of brass. The attached end is made wider, and an ear (C), to which a wire is soldered, projects down beyond the screw. A view looking down on this lever and bracket is shown at Fig. 15. A is the bracket, B the lever, and E the screw or bolt holding the two parts together, with a thin copper washer between them to prevent friction. When the lever and bracket are made fast to the box, a spring (D) should be arranged, so that when the receiver is removed from the hook the lever will be drawn up to the top of the slot. A small contact-plate (F) is made of brass, and fastened at the lower end of the slot. On this the lever should rest when the receiver is on the hook. A contact-wire is soldered to this plate, which in turn is screwed fast to the inside of the box. This mechanism is part of a make-and-break switch to cut out and cut in the bells or telephone, and will be more clearly understood by referring to the diagram in Fig. 17. At the right side of the box a small push-button is made fast, and this, with two binding-posts at the top and four at the underside of the box, will complete the exterior equipment of one end of a line. The construction of the push-button is shown in Fig. 16, A being the box and B the button which passes through a small hole made in the side of the box. C is a strip of spring-brass screwed fast to the box. It must be strong enough to press the small bone or hard rubber button towards the outside of the box. A wire is caught under one screw-head, and another one is passed under the screw-head which holds the other spring (D) to the box. When the button (B) is pushed in, it brings spring C into contact with D, and the circuit is closed. Directly the finger is removed from B the spring (C) pushes it out and breaks the circuit. This button is used only in connection with the call-bells, and has nothing to do with the telephone. The wires leading from the interior of the box pass through the wall-plate and along in grooves to the foot of the binding-posts, which are arranged below the box on the back-board, as shown in Fig. 13. A buzzer or bell is made fast to the inside of the box, unless it is too large to fit conveniently, in which case it may be attached to the wall above or below the box. The Wiring System Fig. 17 shows the wiring system for this outfit, which, when properly set up and connected, should operate on a circuit or line several miles in length, provided that the batteries are strong enough.