C
C. An abbreviation for centigrade when speaking of thermal temperature. In chemistry the centigrade scale is used extensively, but in air temperatures the Fahrenheit scale is universally employed.
Cable, Aerial. A cable that contains a number of wires separately insulated, the entire mass being protected by an external insulation. It is suspended in the air from pole to pole, and sometimes its weight is so great that a supporting wire is carried along with it (usually overhead), the large cable being suspended from it by cable-hangers.
Cable Box. A box to receive cable ends and protect them; also, the box in which cable ends and line-wires are joined. Submarine cable boxes are usually near the ground, while telephone and telegraph cable boxes are mounted on poles, the cables running from the ground and up the poles to the boxes.
Cable-core. The conductors of a cable which make up its interior mass. For the convenience of linemen the wires are often insulated with different-colored materials so that testing is not necessary when making connections.
Cable-hanger. A metallic grip, usually of sheet metal, arranged to clasp two or more wires. It is fastened to the supporting wire by a hook and eye, or by small bolts with thumb-nuts.
Cable-head. A rectangular board equipped with binding-posts and fuse wires so that the connections may be made between the cable ends and the overhead or line-wires of a system.
Cables. An insulated electric conductor of large diameter, often protected by armor or metallic sheathing, and generally containing, or made up, of several separately insulated wires. Cables supply current to traction lines; power, through subterranean passages; communication, by submarine connection; and light, by overhead or underground conduits.
Call-bell. A bell that is rung by pressing a button, and which is operated by electricity.
Calling-drop. A drop-shutter which is worked by electricity in a telegraph or telephone exchange; it denotes the location from which the call was sent in. Small red incandescent lamps have taken the place of the drops in most of the large telephone exchanges, for they are noiseless and do not annoy the operators as the drops and buzzers did.