Key

—In telegraphy, a device for making or breaking the contacts which control the pa age of the current; a steel lever, swung on a pivot, having a rubber handle, which the operator grasps lightly with the thumb and forefingers. On pre ing the lever downward, a platina point projecting under the lever is brought into contact with another platina point set into an insulation of rubber in the base of the key, so that there can be no electrical connection between them unle the key is pre ed down or closed An extra lever at the side of the key is called the ‘‘circuit-closer,’’ and is used as a means of keeping the circuit closed when the hand of the operator is not on the key. When the circuit closer is pushed into its closed position, it makes contact with a bra lip. which latter is fastened to the rubber along with the lower platina point. This, then, has the same effect as though the key was AGER downward and contact made at the points.