Fig. 47.
Fig. 48.
§ 55. The "pull" ([Fig. 47]), as its name implies, makes contact and rings the bell on being pulled. The
knob has a rather long shank bar, around which is coiled a pretty stiff spring. At the farther extremity is an ebonite or boxwood collar ending in a rather wider metal ring. The wires from the bell and battery are connected respectively to two flat springs, a a', by the screws b b'. When the knob is pulled, the metal collar touches both springs, and the circuit is completed. Closely allied to the "pull" is a form of bedroom contact, which combines pear-push or pressel and pull in one device. This will be readily understood on reference to [Fig. 48]. Another form of bedroom pull, with ordinary rope and tassel, consists in a box containing a jointed metal lever, standing over a stud, from which it is kept out of contact by a counter spring. To the projecting end of the lever is attached the bell rope. When this is pulled the lever touches the stud, contact is made, and the bell rings. This is clearly shown in [Fig. 49 A]. In all these contacts, except the door pull ([Fig. 47]) where the friction of the action of pulling keeps the surfaces