Patntograph to Paraffin
with convex covering tiles. A flat paving tile, Dutch or Flemish.
Pantograph. (Draw.) An instrument for copying drawings on an enlarged or reduced scale.
Pantometer. (Math.) Instrument for measuring angles, elevations, etc.
Paper. (Draft.) White and buff are commonly used for finished drawings; both may be had either in sheets or rolls. Good paper should be tough, take pencil and ink well, and have good erasing qualities. For fine work a paper similar to Whatmans handmade is usually used. It is made in three surfaces; hot pressed, with a smooth surface; cold pressed, with a modertely rough surface; and rough, for water-colour sketches.
Paper birch. (Wood) Also spoken of ~s white birch. A large tree growing to a height of 50 to 75 ft. Wood is strong and hard; light brown in colour. Used in the manufacture of spools, shoe lasts, and for paper pulp.
Paper condenser. (Elec.) A condenser having a dielectric of impregnated paper. .
Paper cutter. (Print.) A machine, either power or hand operated, for cutting paper stock.
Paper drill. (Print.) Used for drilling holes in piles of paper.
Paper machine. (Papermkg.) The machine on which the elements of paper are formed, pressed, dried, calendered, wound on reels, cut into widths. and wound into rolls or in some instances, cut into sheets.
Parabola. (Math. and Engin.) A conic section or curve as would be obtained by passing a plane through a cone parallel with its side.
Parabolic girder. (Engin.) A form of bowstring girder, the outline of whose bow is that of a polygon inscribed in a parabola; used on bridge work.
Parachute. (Aero.) An umbrella-like device used to retard the descent of a falling body by offering resistance to its motion through the air.
Parachute canopy. (~ero.) The main supporting surface of a parachute.
Parachute flare. (Aero.)A pyrotechnic device attached to a parachute and designed to illuminate a large area when released from an aircraft at an altitude.
Parachute harness. (Aero.) A combination of straps, buckles, and fastenings used to 'attach a parachute to the wearer.
Parachute pack. (Aero.) A parachute and its container.
Parachute rigger. (Aero.) A person who packs, repairs, and inspects parachutes.
Parachute vent. (Aero.) A distendable opening in the apex of the canopy of a parachute designed to relieve excess pressure and to stabilize the parachute in descent.
Paradox. Something seemingly incredible, yet true.
Paraffin. (Chern.) A translucent, waxy, solid. substance derived principally in the destillation of petroleum.
Parallax to Parasite
Parallax. (Elec.) This occurs when the scale of an electrical instrument, the needle and tfle eye, are not in correct alignment. This is overcome by covering the refleCtion of the needle in the mirror by the needle.
Parallel. Lying side by side; extendeing in the same direction and equidistant at all points; having the same direction; similar.
parllel circuit. (Elec.) A cir(;uit having a common feed and a comon return, -between. which two or more pieces of apparatus are connected each receiving a separate portion of the current flow from the common feed.
Parallel connectted transformer. (Elec.) When two or more transformers have their primary windings connected to the same source of supply in such a manner that the impressed voltage in each case is the same as that of the line.
Parallel forces. (Mech.) When two forces are parallel and act in the same direction but do not start from the same point, the resultant is parallel to both and equal to their sum. When the forces act in opposite directions' the resultant is equal to the difference between the two.
Parallel jaw pliers. (Shopwk.) Pliers equipped with a toggle joint which permits the jaws to remain parallel regardless of the extent of opening.
Parallelogram. (Math.) A foursided figure whose opposte sides are parallel. Area equals base times perpendicular height.
Parallelogram of forces. (Mech.) The resultant of two forces operating at an angle which can be enclosed in a parallelogram. The diagonal is the resultant.
Parallel rulers. (Draft.) A draftsmans tool consisting of two rulers or straight edges connected by pivoted arms in such a way that the edges of the rulers are always parallel, regardless of the distance between.
Parallel. (Mach.) Accurately machined bars or strips of metal, rectangular in section, used for blocking up or leveling work for some machine operation.
Paramount. Superior to all others.
Parapet. (Arch.) A low wall about the edge of a roof, a terrace, or at the side of a bridge.
Parasite drag. (Aero.) That portion of the drag of an aircraft exc1u
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