Dry cell to Duograph.

Dry cell. (Elec.) A primary cell which does away with the liquid electro­lyte so that it may be used in any position.
Dry disk clutch. (Auto.) The driving disks are covered on both sides with a friction material and are driven by keys in the clutch ring which is bolted to the engine flywheel. Called "dry" because no oil or grease must contact the clutch facings.
Dry grinding. Grinding without the use of water or other coolant.
Dry indicator. (Photog.) A powder to detect. moisture; a mixture of 10 parts granulated sugar to 1/10 part methyl violet.
Dry kiln. (Wood) A chamber in which the seasoning of wood is hastened artificially.
Dry rot. A rapid decay of timber which causes it to be reduced to a fine powder.
Dry rubble. (Masonry) Rough stone laid into a wall without mortar. Dry run. (Tel.) A rehearsal without cameras or other equipment.
Dry sand. (Fdry.) Mixtures of sand which, after being dried, become hard and better resist the strain put upon them from molten metal.
Dry-sand core. (Fdry. and Wood Patmkg.) One which has been baked or thoroughly dried in an oven. Dry-sand-cores are. made in core boxes independent of the mold, as distinguished from green­sand cores which are delivered di­rectly in the mold by holes or depressions in the patterns.
Dry spot. (Plast.) Area in laminated. plastics, e.g., laminated glass, where the interlayer and the glass have not become bonded.
Dry steam. Saturated steam which contains no entrained moisture.
Dry weight of an engine. (Aero.) The weight of the engine, includ­ing carburetor and ignition sys­tems complete, propeller hub as­sembly,reduction gears, if any, but excluding exhaust manifolds, oil, and water. If the starter is built into the engine as an integral part of the structure its weight shall be included.
Dry well. (Plumb.) A hole in the ground lined with stone in such a manner that liquid effluent or other sanitary wastes will leach into the surrounding sojl.
Dry wood. Timber from which the sap has been removed by season­ing.
Dryer. (Furn.) The process of evapo­rating moisture from a mold by means of hot air injected, or of a charcoal fire basket, or by baking in an oven.
Drying oil. (Plast.) A special type of oil, such as tung or perilla, whiCh hardens readily when ex­posed to the air; used as an ingre­dient in varnishes.
Drying rack. (Print.) A rack or frame to dry prinied matter.

Dual ignition. An ignition system having two sources of current (such as battery and magneto) and using the same set of spark plugs; also an ignition system having two spark plugs which fire simultaneously for each cylinder.
Dual cone. Speaker consisting of sepa­rate bass and treble cones mounted concentrically and driven by the same coil. See also Coaxial. me­chanical 2-way speaker.
Dub. A copy of recording-usually a taped copy, but sometimes lacquer disc (phonograph record). To "make a dub" or to "dub a recording" is to copy it, though not necessarily in the same tape format. Dubs are generally used for reference pur­poses.
Dubbing. Duplicating an audio and! or video signal such as a composite master tape to make additional tape copies. Dubbing puts the resulting copy or dub one generation away from the tape from which it was 'recorded. Can also refer to erasing an audio track and recording a new track in its place. see 'Audio Dub.'
Ducted port. A type of bass reflex loudspeaker enclosure where the simple opening or "port" is replaced by a tube or a tunnel-like duct.
Dull. An expression describing a recording, playback system, or sound reinforcement system that is deficient iri high frequency response. A dull system would lack "life" or "luster" .
Dummy load. Components or com­ponent (usually a resistor) used in place of the normal load for'a trans­ducer or amplifier. Usually for test or other special purposes.
Ductility. That property of metals by virtue of which they can be drawn out into wires. (Phys.) The property of materials which permits per-manent deformation without failure after the elastic limit has passed. Drawing metal into a wire is a common example of ductility.
Dull-coated paper. (Papermkg. and Print.) A smooth, unglossed enamel paper.
Dull-finish paper. (Print.) Coated stock without glossy finish.
Dull iron. (Fdry.) Iron not as hot as it should be for best pouring.
Dumb-waiter. (Arch.) A type of small elevator, usually operated by hand, for moving food or small supplies between floors.
Dummy. (Print.) A paste-up of page layouts, made from galley proofs and proofs of cuts. (Bookbndg.) The bound, blank pages of a boot< giving an accurate idea how the published work will look.
Dumpy level. (Surv.) Has its vertical axis, the horizontal bar, and the s.upports of the telescope all in one piece to which the spirit level is attached. The dumpy level will stand rougher usage than the wye level, and permits just as accurate work.
Duodecimo. A book page or leaf about 5 by 7Y2 in.
Duograph. (Print.) Two halftone plates made from one copy, usu­ally printed in black and one tint; the two plates being made with different screen angles.