CAPACITY UNIT.--See _Farad_.

CARBON RHEOSTATS.--See _Rheostat, Carbon_.

CARBORUNDUM DETECTOR.--See _Detector_.

CARRIER CURRENT TELEPHONY.--See _Wired-Wireless_.

CARRIER FREQUENCY.--See _Frequency, Carrier_.

CARRIER FREQUENCY TELEPHONY.--See _Wired-Wireless_.

CASCADE AMPLIFICATION.--Two or more amplifying tubes hooked up in a receiving set.

CAT WHISKER CONTACT.--A long, thin wire which makes contact with the crystal of a detector.

CENTIMETER OF CAPACITANCE.--Equal to 1.11 _microfarads_.

CENTIMETER OF INDUCTANCE.--Equal to one one-thousandth part of a _microhenry_.

CELLULAR COILS.--See _Coils, Inductance_.

C.G.S. ELECTROSTATIC UNIT OF CAPACITANCE.--See _Centimeter of Capacitance_.

CHARACTERISTICS.--The special behavior of a device, such as an aerial, a detector tube, etc.

CHARACTERISTICS, GRID.--See _Grid Characteristics_.

CHOKE COILS.--Coils that prevent the high voltage oscillations from surging back into the transformer and breaking down the insulation.

CHOPPER MODULATION.--See _Modulation, Chopper_.

CIRCUIT.--Any electrical conductor through which a current can flow. A low voltage current requires a loop of wire or other conductor both ends of which are connected to the source of current before it can flow. A high frequency current will surge in a wire which is open at both ends like the aerial.

Closed Circuit.--A circuit that is continuous.

Open Circuit.--A conductor that is not continuous.

Coupled Circuits.--Open and closed circuits connected together by inductance coils, condensers or resistances. See _coupling_.

Close Coupled Circuits.--Open and closed circuits connected directly together with a single inductance coil.

Loose Coupled Circuits.--Opened and closed currents connected together inductively by means of a transformer.

Stand-by Circuits.--Also called _pick-up_ circuits. When listening-in for possible calls from a number of stations, a receiver is used which will respond to a wide band of wave lengths.

Armstrong Circuits.--The regenerative circuit invented by Major E. H.

Armstrong.

CLOSE COUPLED CIRCUITS.--See _Currents, Close Coupled_.

CLOSED CIRCUIT.--See _Circuit, Closed_.

CLOSED CORE TRANSFORMER.--See _Transformer, Closed Core_.

CODE.--

Continental.--Same as _International_.

International.--On the continent of Europe land lines use the _Continental Morse_ alphabetic code. This code has come to be used throughout the world for wireless telegraphy and hence it is now called the _International code_. It is given on Page 305. [Appendix: International Morse Code].

Morse.--The code devised by Samuel F. B. Morse and which is used on the land lines in the U. S.

National Electric.--A set of rules and requirements devised by the _National Board of Fire Underwriters_ for the electrical installations in buildings on which insurance companies carry risks. This code also covers the requirements for wireless installations. A copy may be had from the _National Board of Fire Underwriters_, New York City, or from your insurance agent.

National Electric Safety.--The Bureau of Standards, Washington, D. C., have investigated the precautions which should be taken for the safe operation of all electric equipment. A copy of the _Bureau of Standards Handbook No. 3_ can be had for 40 cents from the _Superintendent of Doc.u.ments_.

COEFFICIENT OF COUPLING.--See _Coupling, Coefficient of_.

COIL AERIAL.--See _Aerial, Loop_.

COIL ANTENNA.--See _Aerial, Loop_.

COIL, INDUCTION.--An apparatus for changing low voltage direct currents into high voltage, low frequency alternating currents. When fitted with a spark gap the high voltage, low frequency currents are converted into high voltage, high frequency currents. It is then also called a _spark coil_ and a _Ruhmkorff coil_.

COIL, LOADING.--A coil connected in the aerial or closed oscillation circuit so that longer wave lengths can be received.

COIL, REPEATING.--See _Repeating Coil_.

COIL, ROTATING.--One which rotates on a shaft instead of sliding as in a _loose coupler_. The rotor of a _variometer_ or _variocoupler_ is a _rotating coil_.

COILS, INDUCTANCE.--These are the tuning coils used for sending and receiving sets. For sending sets they are formed of one and two coils, a single sending coil is generally called a _tuning inductance coil_, while a two-coil tuner is called an _oscillation transformer_.

Receiving tuning coils are made with a single layer, single coil, or a pair of coils, when it is called an oscillation _transformer_. Some tuning inductance coils have more than one layer, they are then called _lattice wound_, _cellular_, _basket wound_, _honeycomb_, _duo-lateral_, _stagger wound_, _spider-web_ and _slab_ coils.

COMMERCIAL FREQUENCY.--See _Frequency, Commercial_.

CONDENSER, AERIAL SERIES.--A condenser placed in the aerial wire system to cut down the wave length.

CONDENSER, VERNIER.--A small variable condenser used for receiving continuous waves where very sharp tuning is desired.

CONDENSER.--All conducting objects with their insulation form capacities, but a _condenser_ is understood to mean two sheets or plates of metal placed closely together but separated by some insulating material.

Adjustable Condenser.--Where two or more condensers can be coupled together by means of plugs, switches or other devices.

Aerial Condenser.--A condenser connected in the aerial.

Air Condenser.--Where air only separates the sheets of metal.

By-Pa.s.s Condenser.--A condenser connected in the transmitting currents so that the high frequency currents cannot flow back through the power circuit.