Wall Telephone Hooks. Kellogg. A typical form of hook switch, as employed in the ordinary wall telephone sets, is shown in Fig. 83, this being the standard hook of the Kellogg Switchboard and Supply Company.  In this the lever 1 is pivoted at the point 3 in a bracket 5 that forms the base of all the working parts and the means of securing the entire hook switch to the box or framework of the telephone.  This switch lever is normally pressed upward by a spring 2, mounted on the bracket 5, and engaging the under side of the hook lever at the point 4.  Attached to the lever arm 1 is an insulated pin 6.  The contact springs by which the various electrical circuits are made and broken are shown at 7, 8, 9, 10, and 11, these being mounted in one group with insulated bushings between them; the entire group is secured by machine screws to a lug projecting horizontally from the bracket 5.  The center spring 9 is provided with a forked extension which embraces the pin 6 on the hook lever.  It is obvious that an up-and-down motion of the hook lever will move the long spring 9 in such manner as to cause electrical contact either between it and the two upper springs 7 and 8, or between it and the two lower springs 10 and 11.  The hook is shown in its raised position, which is the position required for talking.  When lowered the two springs 7 and 8 are disengaged from the long spring 9 and from each other, and the three springs 9, 10, and 11 are brought into electrical engagement, thus establishing the necessary signaling conditions.

[Illustration:  Fig. 83.  Long Lever Hook Switch]

The right-hand ends of the contact springs are shown projecting beyond the insulating supports.  This is for the purpose of facilitating making electrical joints between these springs and the various wires which lead from them.  These projecting ends are commonly referred to as ears, and are usually provided with holes or notches into which the connecting wire is fastened by soldering.

Western Electric. Fig. 84 shows the type of hook switch quite extensively employed by the Western Electric Company in wall telephone sets where the space is somewhat limited and a compact arrangement is desired.  It will readily be seen that the principle on which this hook switch operates is similar to that employed in Fig. 83, although the mechanical arrangement of the parts differs radically.  The hook lever 1 is pivoted at 3 on a bracket 2, which serves to support all the other parts of the switch.  The contact springs are shown at 4, 5, and 6, and this latter spring 6 is so designed as to make it serve as an actuating spring for the hook.  This is accomplished by having the curved end of this spring press against