Fig. 91. TWO WIRE CLEAT.

Fig. 92. THREE WIRE CLEAT.

Cleat, Crossing.

A cleat with grooves or apertures to support wires which cross each other. Two or three grooves are transverse, and on the under side, as above; one groove is longitudinal and on the upper side.

Cleavage, Electrification by.

If a ma.s.s of mica is rapidly split in the dark a slight flash is perceived. Becquerel found that in such separation the two pieces came away oppositely charged with electricity. The splitting of mica is its cleavage.

Clock, Controlled.

In a system of electric clocks, the clocks whose movements are controlled by the current, regulated by the master or controlling clock.

Synonym--Secondary Clock.

Clock, Controlling.

In a system of electric clocks the master clock which controls the movements of the others, by regulating the current.

Synonym--Master Clock.

Clock, Electric Annunciator.

A clock operating any form of electric annunciator, as dropping shutters, ringing bells, and the like. It operates by the machinery closing circuits as required at any desired hour or intervals.

128 STANDARD ELECTRICAL DICTIONARY.

Clock, Electrolytic.

A clock worked by the electrolytic deposition and resolution of a deposit of metal upon a disc. It is the invention of Nikola Tesla. A metallic disc is mounted on a transverse axis, so as to readily rotate.

It is immersed in a vessel of copper sulphate. A current is pa.s.sed through the bath, the terminals or electrodes being near to and facing the opposite edges of the disc, so that the line connecting the electrodes lies in the plane of the disc. If a current is pa.s.sed through the solution by the electrodes, copper is deposited on one side of the disc, and as it rotates under the influence of the weight thus acc.u.mulated on one side, the same metal as it is brought to the other side of the disc is redissolved. Thus a continuous rotation is maintained. The cause of the deposition and solution is the position of the disc; one-half becomes negative and the other positive in their mutual relations.

Clock, Self-winding Electric.

A clock which is wound periodically by an electric motor and battery.

Clockwork, Feed.

In arc-lamps the system of feeding the carbon or carbons by clockwork whose movements are controlled by the resistance of the arc. This system is employed in the Serrin, and in the Gramme regulators, among others.

The carbons, if they approach, move clockwork. The movement of this is stopped or freed by an electro-magnet placed in shunt around the arc and carbons.

Cloisons.

Part.i.tions or divisions; applied to the winding of electro-magnets and coils where the winding is put on to the full depth, over single sections of the core, one section at a time, until the whole core is filled up.

Closure.

The closing or completion of a circuit by depressing a key or moving a switch.

Clutch.

In arc lamps a device for the feed of the upper carbons. In its simplest form it is simply a plate or bar pierced with a hole through which the carbon pa.s.ses loosely. The action of the mechanism raises or lowers one end of the plate or bar. As it rises it binds and clutches the carbon, and if the action continues it lifts it a little. When the same end is lowered the carbon and clutch descend together until the opposite end of the clutch being prevented from further descent, the clutch approaches the horizontal position and the rod drops bodily through the aperture.

The cut shows the clutches of the Brush double carbon lamp. In practice the lifting and releasing as regulated by an electro-magnet are so very slight that practically an almost absolutely steady feed is secured. A similar clutch is used in the Weston lamp.

129 STANDARD ELECTRICAL DICTIONARY.

Clutch, Electro-magnetic.

A clutch or appliance for connecting a shaft to a source of rotary motion while the latter is in action. In one form a disc, in whose face a groove has been formed, which groove is filled with a coil of wire, is attached to the loose wheel, while the shaft carries a flat plate to act as armature. On turning on the current the flat plate is attached, adheres, and causes its wheel to partake of the motion of the shaft.

Contact is made by brushes and collecting rings.

In the cut, A A is the attracted disc; the brushes, B B, take current to the collecting rings, C. The magnetizing coil is embedded in the body of the pulley, as shown.

Fig. 93. CLUTCH OF BRUSH LAMP.

Fig. 94. ELECTRO-MAGNETIC CLUTCH.

130 STANDARD ELECTRICAL DICTIONARY.

Coatings of a Condenser or Prime Conductor.

The thin conducting coatings of tinfoil, gold leaf or other conducting substance, enabling the surface to receive and part with the electric charge readily. Without such a coating the charge and discharge would be very slow, and would operate by degrees only, as one part of a non-conducting surface might be densely charged and another part be quite devoid of sensible charge.

Code, Cipher.

A code of arbitrary words to designate prearranged or predetermined words, figures or sentences. The systems used in commerce have single words to represent whole sentences or a number of words of a sentence.

This not only imparts a degree of secrecy, but makes the messages much shorter. Codes are used a great deal in cable transmission.

Code, Telegraphic.

A telegraphic alphabet. (See Alphabets, Telegraphic.)

Coefficient.

In algebra, the numerical multiplier of a symbol, as in the expression "5x," 5 is the coefficient. In physics, generally a number expressing the ratio or relation between quant.i.ties, one of which is often unity, as a standard or base of the set of coefficients. Thus the coefficient of expansion by heat of any substance is obtained by dividing its volume for a given degree of temperature by its volume at the standard temperature as 0? C., or 32? F. This gives a fraction by which if any volume of a substance, taken at 0? C., or at whatever may be taken as the basic temperature, is multiplied, the expanded volume for the given change of temperature will be obtained as the product. A coefficient always in some form implies the idea of a multiplier. Thus the coefficient of an inch referred to a foot would be 1/12 or .833+, because any number of inches multiplied by that fraction would give the corresponding number of feet.

[Transcriber's note: 1/12 is 0.0833+]