N to Neutral axis

N to Nanosecond

n. Symbol for neutron.

N. Symbol for newton, neutron num ber.

N. Symbol for Avogadro number. NAB. (National Association of Broad­ casters.) Most widely used standard of tape recording techniques.

NAB Hub. The. cylindrical object of the centre of 26 em and 35 em diameter reds or pancakes of pro­fessional recording tape. The term hub is sometimes used interchange­ably with pancake since the pan­cake is wound onto a hub (although NAB. reels also have hubs at their centre). NAB Curve. A ~idely used, standard tape record/playback equalisation curve established by NAB.

NAB Reel Adaptors. Special plastic or metal inserts that are placed on he takeup and supply spindles of a tape machine so it can utilise NAB hubs (pancakes) or NAB reels. N.A.C.A. cowling. (Aero.)A cowling enclosing a radial air-cooled engine, consisting of a hood, or ring, and a portion of the body behind' the engine, so aITanged that the cooling air smoothly enters the hood at the front and leaves through a smooth annular slot between the body and the rear of the hood.

Nacelle. (Aero.) An enclosed shelter for passengers or for a power plant. A nacelle is usually shorter than a fuselage and does not carry the tail unit.

Nail. A slender piece of metal, one end of which is pointed, the other end having a head, either flattened or rounded. It is a common means of fastening together several pieces of wood or other material by strik­ing the head with the hammer.

Nail puller. (Mech.) (I) The ordi­nary small pinch bar or wrecking bar provided with a forked end which passes about the nail below the bead. (2) A mechanical device with two jaws, one of which has a heel, which provides a leverage for gripping the nail and for pulling it from the wood.

Nail punch. (Woodwkg.) Same as NAIL SET.

Nail set. (Wood Patmkg.) A small rod of steel 4 or 5 in. long with one end drawn to a taper and slightly cupped to prevent it from slipping off the head of the nail; used in sinking the head of a nail below the surface.

Nanofarad. One-thousandth of a microfarad (nF), same as kilo­picofarad (kpF).

Nanosecond. One-thousandth of a microsecond (nS). Negative resistae to Neutral axis platinum, etc., is the negative elec­ trode. .

Negative resistance. A characteristic of certain electronic devices wherein the current increases as the voltage decreases.

Negative side of circuit. (Elec.) The conducting path of the circuit from the current-consuming device back to the source of supply.

Neo-classic. (Arch.) (1) new classic; (2) revival of.classic taste in archi­tecture, furniture, etc., usually ap­plied to early 18th century revival due to Pompeian discoveries.

Neon. A chemically inert gaseous el­ement occuring in small amounts in the earth's atmosphere, used chiefly in orange-red, tubular electrical dis­charges lamps.

Neon light. (Elec.)A type oflamp with twCJ electrodes instead of a filament. The ionization of neon gas contained in the tube produces illumination. Such lights are extensively used in advertising displays.

Neon-light ignition timing. (Auto.) By connecting a small neon light by means of wires in a secondary circuit of the ignition wiring in series with No. I spark plug, the light flashes on and off as the breaker makes contact and opens. An engine is in proper time when the light flashes directly on a tim­ing mark on the flywheel or vibra­tion dampener.

Nep. (Textile) The small knots in cot­ton due to inferior bolls or poor ginning.

Neper. A dimensionless unit used for comparing two currents, almost exclusively in telecommunication engineering, the two currents be­ing I,lsually those entering or leav­ing a transmission line or other transmission network.

Nemst lamp. (Elec.) An .incandes­cent lamp whose lighting element consists of a pencil composed of the refractory oxides of rare emit.

Nested tables. (Furn.) A set of ta­bles, usually four, made to fit one into the other when not in use.

Nest of saws. (Woodwk.) A combi­nation of compass saws consisting of several blades of different lengths for use in the same handle. Used for light work.

Nest plate. (Plast.) A retainer plate with a depressed area for cavity blocks used in injection molding.

Network. A group of transmitting stations linked by wire or micro­wave relay soo that the same pro­'gram can be broadcast or telecast by all.

Neutral. (Auto.) The gear-shift posi­tion in which engine power is not transmitted to the driving axle, i.e., the speed-change gears are dis­engaged. (Elec.) Neither positive nor negative.