Chokedamp to Cinna-bar.

Chokedamp. (Chem.) Name applied to carbon dioxide, especially when present in mines.
Chop inlay. (Furn.) An early form of inlay in which pieces were fit­ted into a solid surface.
Chord. (Aero.) An arbitary datum line from which the ordinates and angles of an airfoil are measured.
(Engin.) The principal member of a truss, either top or bottom. (Math.) A straight line connecting the ends of an arc.
Chordal pitch. (Gear.) The distance from a point on a gear tooth to a corresponding point on the next tooth measured as a chord of the pitch circle.
Chord length. (Aero.) The projected length of an air-foil section.
Chords. Known to some 'natural' musos as 'shapes' on key or fret boards, chords are the accepted way of playing groups of notes. The most basic of all standard chords usually comprise three and no more notes. A chord structure is a term used to describe the se­quence and placing of separate chords within a complete piece of music.
Choroid. A dark layer inside the eye which stops any light being re­flected back.
Chorus. commonly referred to as a 'hook' to a song, the chorus is the bit we all remember and hum to ourselves on the bus; classical buffs sometimes call it the 'refrain' . Cho­rus is also a word used to describe the effect of two or more similar signals meeting our ears at slightly different times. A chorus unit is a time delay based effect developed by the clear Rolan People in Japan. What it does is split the input signal into two and delay it for a short while, usually 5-45 IDS, then let it out in a mix with the original signal. In­troducing a low frequency oscillator to modulate and change the pitch of the delayed signal gives a swoosh, stringy sort of effect on less energetic sounds. Flanging is an extremely similar (though more boisterous) effect.
Chroma. (Colour) Refers to the bril­liancy, strength or intensity of a col­our. Neutralization or graying of a colour brings about a loss in chroma.
Chromatic aberration. The variation of either the focal length or the wagnificatin of a lens with different wave lengths of light.
Chromaluminium. (Metal.) A very strong aluminium alloy. .
Chromate. (Chern.) Salt of chromic acid.
Chromaticity. The quality of a colour as determined by its wave length and its purity.
Chrome nickel steel. (Metal.) A rather expensive steel, hard to machine, forge, and heat treat. In most cases chrome vanadium steel or nickel steel will serve the same purpose at lower cost.
Chrome tannage. (Leather.) A proc­ess of tanning by the use of chromic acid.
Chromevanadium steel. (Engin.) A tough steel containing 0.87 per cent

Chromium chromium and 0.18 per cent vanaidium. After heat treatment it has an ultimate strength of21O,000 pounds per square inch and an elastic limit of 191 ,500 pounds per square inch.
Chromium. (Metal.) Symbol, Cr. A grayish-white metallic element; specific gravity, 6.50; melting point, 2939°F. Used in alloy steels and in plating.
Chromium oxide. (Ceram.) A green colouring agent used in glazes.
Chromium - plated tools. (Metalwk.) Chromium plating of tools and gauges is used to build up worn parts, producing a very hard surface which does not have to be ground and from which chips clear readily.
Chromium plating. Extensively used to provide a durable, bright fmish, particularly on such items as automobile parts and hardware exposed to unfavourable weather conditions. It has to a great degree taken the place of nickel plating.
Chromium steel. (Metal.) Steel con­taining from 1 to 2 per cent chro­mium. It is very hard. and tough; used as an automotive alloy steel, and for projectiles, armor plate, etc.
Chromodizing. (Metal.) A hot-dip process of forming a hard-surface film on aluminium alloys; some­ times used in place of anodizing.
.Chronometer . A precision watch or other accurate, portable time­keeping device.

Chrysotite. Long-fibre absestos. Chuck. (Shopwk.) In itself a very broad term, meaning a device for holding a rotating tool or work dur­ing an operation. There are many dif­ferent kinds of chucks for various purposes.
Chucking. (Mach.) In lathe turning, the mounting of the work in the chuck.
Chucking reamer. (Shopwk.) Spiral fluted chucking reamers with there
and four grooves are employed for enlarging cored holes, etc. They are also made with oil passages through them, and in this form are adapted to operating in steel. Another style
is used for finishing holes that have been roughed out.
Churning. (Fdry.) Agitating the fluid metal in mold by moving a small, heated iron rod up and down in the feeder in order to insure solid castings. .
Churn molding. (Furn.) -A zigzag molding often seen in Norman architecture.
Chute. An inclined trough or tube to guide sliding objects from a higher to a lower level.
Cincture. (Arch.) A ring or fillet at the top and bottom of a column serving to divide the shaft from its capital and its base.
Cinder bed. (Fdry.) A layer of cinders beneath a mold to permit the escape of gas.
Cine-camera. A motion-picture carn­era.
Cinna-bar. (Metal.) The ore of mer­cury. Also used asa pigment (ver­

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