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Glossary of Bridge Terminology



Rabbet: A half groove along the edge of a board. To cut such a groove.

Rabbet Joint: Same as "Half-and-half Joint." -- A joint having both parts dapped or gained-in equally on their faces.

Rabbeting Machine: A machine for cutting rabbets in boards.

Rabble: A bar with one end bent at right angles like a poker, used in puddling furnaces.

Rabbling: Same as "Puddling." -- Converting cast iron into wrought iron by melting and stirring in a reverberatory furnace.

Rack: A straight iron bar having teeth for engaging those of a gear or a worm. Used to convert rotary motion into rectilinear, or vice versa.

Rack and Pinion: A combination of a rack and a pinion working together.

Rack-and-pinion Jack: A jack using a rack and pinion to attain its lifting motion.

Rack-circle: A rack bent into the form of a circle.

Rack-rail: Same as "Rack."

Rack Tooth: The tooth on a rack which meshes with a gear.

Racked-back: Built in steps or offsets.

Racking: Shaking so that the connecting rivets are loosened and the structure thus permanently injured.

Radial-arm: A crank or rod revolving about a centre at one end, such as the crank of a windlass.

Radial Drill: A machine rock drill in which the drill tool is fastened to a radial arm.

Radial Rod: A rod connecting the roller of a rim-bearing draw-span with the centre casting.

Radial Strut: One of a series of struts radiating from a fixed point, as the spokes of a wheel, or the radial braces of a turntable, or a swing-span drum.

Radian: The unit of circular measure equal to an angle which has a subtending arc of the same length as the radius.

Radius of Curvature: The radius of the circle of curvature.

Radius of Gyration: The radius of gyration of a body about a given axis is the distance from the axis of rotation to the centre of gyration, and is equal to the square root of the mean of all the squares of the distances from the axis of rotation to all the points in the body.

Radius Tool: A tool used by cement finishers to form a round corner on exposed concrete work.

Raft Dog: An iron bar with ends bent over and pointed for securing logs together in a raft.

Rafter: One of the timbers or joists in a roof to which the boards are fastened.

Rag Bolt: Same as "Barb Bolt." -- A bolt having jagged edges so as to prevent its being withdrawn from the object into which it is driven.

Rag Wheel: A "Sprocket Wheel."

Rail: A specially shaped bar adapted to a particular purpose. It may be of wood, stone, concrete, or metal. Generally used for supporting vertical loads.

Rail-bender: A mechanical device used for bending rails to a predetermined curvature before laying.

Rail-brace: A knee casting attached to the railroad tie to prevent the spreading and overturning of rails, especially on curves and switches.

Rail-chair: A metal block or shape used under a rail to give it a greater bearing on the tie.

Rail Clamp: A wedge used for tightening a rail in a rail chair.

Rail-guard: On English locomotives, a bar projecting down in front of the front wheel to within two inches front the rail to knock off any object which might be resting on the rail. Also sometimes used for "Guard-rail."

Rail Jack: Same as "Track Jack." -- A lever jack having a tongue near the bottom of the stem and on the side opposite the lever. This tongue can readily be inserted under a rail or tie and a portion of the track raised by pumping the lever.

Rail Joint: The joint between railway rails.

Rail-lift: A device used on swing spans for lifting the ends of the rails thereon, so as to clear obstructions on adjacent spans as the draw is swung open.

Rail-lock: A device used on swing spans for locking the rails at the ends of the span after closing the draw.

Rail Saw: A saw used at the mills for cutting rails.

Rail-section: The cross-section of a rail.

Rail Splice: The joining of two rails by splice bars and bolts.

Rail Tongs: Tongs with hooked ends and spreading handles, used for carrying rails.

Railing: See "Rail."

Railroad Curve: Curve used on railways or railway work. Also a draftsman's tool or template for drawing such curves.

Railroad Jack: See "Rail Jack."

Railway Bridge: A bridge which carries railway traffic.

Raising Hammer: A hammer used for deeply dishing metal plates.

Rake: The inclination to the vertical which a member of a bridge takes.

Ram: The hammer of a pile driver; a heavy timber or bar used for driving pins in a bridge.

Rammed: Driven with great force, as a pile is rammed into the ground by the blows of the hammer.

Ramp: An inclined plane connecting two levels.

Random Bond: A bond in which the stones or bricks are not laid in regular courses at all.

Random Course: Same as "Irregular Course." -- A course in which the thicknesses of the stones vary at intervals.

Random Masonry: Masonry composed of blocks having squared joints, but of varying size and not laid in courses.

Random Rubble or Uncoursed Rubble: Rubble masonry laid up without regard to courses.

Random Tooled Dressing: In stonework a finish cut with a broad tool into irregular flutings.

Range Masonry: Masonry composed of blocks having squared joints and which are laid in courses varying in thickness.

Range of Stress: The limits between which the stress or stresses in a member vary as the load changes.

Range Pole: A slender, painted pole having red and white bands alternating to give distinctness. Used by surveyors in sighting and running lines.

Rankine's Formula: One of the most widely known formulae for the design and investigation of columns employed in engineering practice:

wherep = allowable unit stress for the column
s = allowable unit stress for short columns
a = a constant
l = length
andr = radius of gyration in reference to an axis normal to a plane in which flexure takes place

Rasp: A coarse-cut file.

Rat-tail File: A small, circular, tapering file which resembles a rat's tail.

Ratchet: A mechanism consisting of a ratchet wheel and a pawl or pawls (or sometimes of a rack and pawl), so arranged that a movement of the pawl in one direction causes a partial revolution of the ratchet wheel while a reverse motion of the pawl has no effect thereon. It is often called a "Click."

Ratchet Coupling: A shaft coupling consisting of a ratchet-wheel on one shaft turning a similar one on the other shaft.

Ratchet Drill: Any drill operated by a ratchet mechanism.

Ratchet Gear: A gear wheel having sharp-pointed teeth, non-symmetrical about a radial line, leaning away from the direction of rotation so as to engage a pawl which catches on the tooth and prevents backward motion.

Ratchet Jack: Any jack worked with a ratchet.

Ratchet Punch: A punching machine that is operated by means of a ratchet wheel.

Ratchet Reamer: A reamer rotated by a ratchet mechanism.

Ratchet Wheel: A toothed wheel forming part of a ratchet mechanism.

Ratchet Wrench: A wrench provided with a handle engaging a ratchet.

Rate of Strain: The ratio of the deformation to the original length of a member.

Rational Formula: A formula derived from fundamental principles.

Rattler: A cylinder with ends closed, as in a barrel, set on trunnions for rotating. It is used for cleaning small castings by rolling and tumbling them over each other, and also for making abrasion tests of stone, brick, etc.

Rattling: Working a rattler.

Raymond Pile: A form of filling pile in which a steel shell is driven into the ground and allowed to remain, at the time of withdrawing the mandrel, so as to form a lining for the hole into which the concrete is poured.

Rays: The lines in a force diagram drawn from a selected pole to the ends of the several lines representing the forces in the load line. See "Force Diagram."

Reach: The distance or limit within which a machine can operate, as the reach of a derrick. Also used to denote an unbroken stretch of a stream.

Reaction: A passive force set up in opposition to an initial, active force, e. g., the upward pressure on the bottom of a beam resting on a support, equal in amount to the downward pressure from the beam.

Real Horsepower: Same as "Indicated Horsepower." -- The power developed in the cylinder of a steam engine as determined from an indicator diagram. It is equal to the mean effective pressure in pounds per square inch, multiplied by the area of the piston in square inches, by the piston speed in feet per minute, and divided by thirty-three thousand (33,000).

Ream: To enlarge a hole by means of a cutting tool having fluted cutters on the side.

Reamer: A tool having fluted sides with cutting edges used for enlarging holes. Also the machine that rotates the cutting tool.

Reaming: Cutting with a reamer in order to enlarge rivet holes in steel.

Reaming-bit: The cutting tool used with a reaming machine.

Reaming Iron: A round, tapering tool with cutting edges for enlarging rivet holes. A reamer. An iron tool used to open the seams between planks, so that they may be more readily calked.

Rebate: Same as "Rabbet."

Recarburization: The adding of carbon in some form to metal partially decarburized in some steelmaking process in order to obtain the proper percentage of carbon in the finished product.

Receiving Valve: A valve admitting the flow of a liquid.

Reciprocal: The quotient resulting from the dividing of unity by any quantity is the reciprocal of that quantity.

Reciprocate: To move alternately back and forth.

Reconnoisance: A preliminary investigation in the field for an engineering project.

Rectangle: A plane, four-sided figure having four right angles and the opposite sides equal and parallel.

Rectangular Coordinates: A system of coordinates in which the position of any point is defined by its distances from two lines, called axes, making right angles with each other; or from three mutually perpendicular planes.

Red Lead: An oxide of lead-used as a pigment for paint.

Red Ochre: A variety of ochre having a red color, used for paint.

Red Short: A condition of brittleness in iron at red heat.

Red-short Iron: Iron containing sulphur, copper, or arsenic, which will cause it to crack when bent at a red heat, but permitting of considerable tenacity when cold.

Reduced Load Contour: A graphical means of representing the combination of different loads coming upon a structure, so as to give the value of the combination at any point by the ordinate to a curve known as the "Reduced load contour."

Reduced Scale: An undersized delineation of an object.

Reducer: A pipe coupling for joining pipes of different sizes.

Reduction: The production of metal from ore. Lessening in size.

Redundant Member: A superfluous member. Its use is avoided as much as possible in the most approved American bridge-engineering practice.

Reel: A cylindrical drum, spool, or frame upon which is wound a rope, chain, or hose.

Reentrant Angle: An angle in which the vertex points inside the figure of which it forms a part.

Reeve: To pass a rope through a pulley block or an eye.

Reference Hub: A stake driven flush or nearly so with the ground and used to reference, or to tie, a surveyor's line or point.

Referencing: A method of fixing the location of a line or point by measuring from it to some permanent object and recording such measuring for future recovery of the said line or point.

Refined Iron: An iron made from muck bars cut up, mixed with scrap iron, reheated, and rolled.

Refuge-bays: Platforms built on the side of a trestle or bridge so that men and handcars can be gotten out of the way of approaching trains. Also vertical recesses, large enough for several men to stand up in, left in the side of a wall adjoining a railroad track.

Refusal of Pile: That condition in pile driving when further driving fails to increase the penetration.

Regenerative Furnace: An open-hearth furnace using producer gas as a fuel, but so arranged that the gas is conducted to the hearth area through a passage-way filled with red-hot bricks stacked to form an open checkerwork. As the hot gas enters the furnace, it is mingled, in proper proportions, with air similarly heated; so that complete combustion is produced. The escaping hot gases are conducted through a second passage-way filled with bricks, which absorb much of the waste heat. The two passage-ways are used alternately to heat the producer gas as it is fed into the furnace.

Regular Course: A course in which the thickness of stones is uniform throughout.

Regular Curve: Same as a "Simple Curve."-- A curve of constant radius.

Re-heating: Heating a second time; used in tempering steel.

Reinforced Concrete: Concrete in which steel bars are inserted to strengthen it, principally by resisting the tensile stresses induced by external forces.

Reinforced Concrete Floor: A floor composed of reinforced concrete slabs.

Reinforcing Bar: A bar or rod placed in concrete constructions to increase their resistance, especially to bending and shear.

Reinforcing Plate: An extra plate used to reinforce or strengthen a member.

Relative Rigidity: A comparison of the rigidities of two bodies.

Relaying Rails: Second-hand rails which are too much worn to carry heavy traffic at high speed and at frequent intervals, but with sufficient section left to serve for switch tracks, guard rails, etc.

Relieving Arches: Arches which are built at the back of a retaining wall with their axes perpendicular to the wall, in order to relieve the structure from a portion of the lateral thrust, and to increase the resistance to overturning by the additional weight of masonry and its superposed earth load.

Render: Same as "Reeve."

Repair Link: A split link used temporarily for repairing a chain.

Repeated Stress: A stress due to a load which is applied to and removed from a body a great number of times.

Rephosphorization: Adding phosphorus when too much has been removed during the manufacture of steel.

Replacing Switch: A device used for replacing on the track the wheels of derailed cars.

Repose: Inaction. Rest.

Rerailing Guard: A casting or device attached to the rails near the end of a railway structure so that, if an engine or car is derailed, it will run back on the track.

Reset: To place in position a second time. The second set in mortar which has been disturbed after setting up the first time.

Residual: Pertaining to or having the nature of a residuum. Remaining when all required constituents have been removed.

Residual Deformation: Deformation left in a member after the forces causing same have been removed. Same as Permanent Set.

Residual Shear: A permanent shear deformation.

Resilience: The amount of energy which can be stored in an elastic body, up to a given stress per square inch, and which can be given out again by the body as useful work.

Resiliency: The property possessed by an elastic body of absorbing energy as it is deformed and returning same when released.

Resilient: Having resiliency.

Resistance: The passive opposition or reaction to any action.

Resistance Box: A box containing resistance coils.

Resistance Coil: A coil of wire which offers a definite resistance to the passage of an electric current.

Resistance of Materials: That property of bodies, due to molecular forces, by virtue of which they oppose the displacement of their molecules. The resistance which a body offers to distortion, or to deformation by an external force. Also called the strength of materials. This term is also applied to that branch of mechanics which deals with the phenomena of resistance.

Resisting Moment: The moment which opposes distortion, displacement, or overturning. Sometimes loosely used for "Moment of Resistance."

Resolution: The resolving of forces into their components.

Resolve: To analyze a force into its several component forces according to the principle of the "Parallelogram of Forces."

Rest Pier: A pier which supports one of the ends of a draw span. Submerged Pier: A pier entirely below the water line.

Restitution: The ability of an elastic body to recover from deformation due to impact.

Restoring Steel: Treating burnt steel by heating and mechanically working the metal.

Resultant, or Resultant Force: A directed force having an effect equivalent to that of two or more other directed forces.

Resultant Force: Same as "Resultant."

Resultant Stress: The stress resulting from combining all the stresses that act on a piece simultaneously.

Retaining Wall: A wall built to sustain a lateral pressure, such as an earth thrust.

Retardation: A decreasing of velocity, opposed to acceleration of velocity. Sometimes termed negative acceleration.

Retempering Mortar: The wetting and stirring up of mortar after partial setting. A most reprehensible practice.

Reticular: Formed like a net; network.

Reticulated Bond: A form of masonry bond in which the stones are square and are laid lozengewise, so that the joints resemble the meshes of a net.

Return: The termination of the drip-stone or hood-moulding of a door or window. A 180 degree bend in a pipe or conduit.

Reverberatory Furnace: A furnace having a vaulted ceiling which deflects the flames and heat toward the hearth where the ore is to be fused, the fuel being separated from the ore by a compartment.

Reversal: A change to the opposite kind, sign, pole, or direction.

Reversal of Stress: The changing of stress from tension to compression or vice versa.

Reverse Curve: A continuous curve formed of two arcs of opposing curvature.

Revet: To face the bank of a stream with wood, mattress, stone, or concrete to prevent erosion.

Revetment: The facing of wood, mattress, stone, or concrete placed to prevent erosion.

Revolving Draw: A draw which turns in a horizontal plane.

Revolving Draw Bridge: A draw bridge which turns in a horizontal plane.

Rheostat: An electrical instrument for regulating the amount of resistance in a circuit.

Rib: An extra and external portion of a body giving it additional strength and stiffness. The truss or girder of an arch bridge.

Rib-shortening: The contraction in an arch rib due to the axial stress set up by the loading or by a rise in temperature.

Rich Lime: Same as "Fat Lime." -- A lime rich in protoxide of calcium.

Rig: To fit out with what is needed. To put a machine in condition for using.

Rigging: The ropes, pulley-blocks, etc. needed to fit out a derrick or similar machine.

Right Arch: An arch in which the faces are perpendicular to the axis of the soffit.

Right Forward: The American method of building a skew arch by constructing a number of short right arches adjoining each other, each one springing from a skewback which is ahead of or back of its neighbor. This is to avoid the use of spiral joints between the voussoirs, a construction which prevails in European practice.

Right-handed Nut: A nut having a right-hand thread.

Right-handed Screw: A screw having a right-hand thread.

Right-handed Thread: A spiraling in such a direction that a clockwise rotation of the bolt or screw produces a forward motion of the bolt.

Right-line Formula: A column formula in which the allowable unit working stress is made to vary as the first power of  l / r thus --

wherep = allowable working stress
a = allowable unit stress for short columns
b = a constant
l = length
andr = the least radius of gyration

Right of Way: The land or water rights necessary for the roadway and its accessories.

Righting Moment: The moment that tends to right a floating body after displacement.

Rigid: Resisting change of form; stiff; firm; not pliant or flexible.

Rigid Body: A body possessing rigidity or stiffness.

Rigidity: The quality of being rigid or resistant to distortion.

Rim Bearing: A term applied to swing spans to indicate that the dead load is supported by a circular girder near the periphery of the pivot pier instead of near its axis.

Rim Bearing Draw: A swing span supported on a rim or drum.

Rim-bearing Turntable: A turntable having a circular girder, or rim, to transfer the load to a set of rollers.

Rim Saw: A type of circular saw in which the teeth are a part of a detachable ring that is mounted on a central disk.

Rind-gall: A defect in timber due to a bruise in the bark that causes a hard spot in the wood to which the succeeding layers of wood do not adhere.

Ring: A solid generated by the revolution of a closed curve about an axis in the plane of the said curve, but lying outside thereof.

Ring Bolt: Same as "Eye Bolt." -- A bolt having a loop or eye at one end in place of the customary flat head.

Ring Chain: A chain having rings at the ends and often one or more intermediate ones.

Ring Course: A course of masonry parallel to the face of the arch.

Ring Dogs: A pair of dogs connected by a ring.

Ring Dolly: A dolly having a handle attached to two circular plates. These plates have a series of holes near the circumference on one side and a bucking bar on the other. A tap bolt goes through any of the holes and fastens to the handle, thus placing the bucking bar at any angle required.

Ring Heart: A cleavage along the surface of an annular ring about half way between the heart and the bark of a tree.

Ring Joint: A circular flange joint.

Ring Shake: Same as "Ring Heart," except that the cleavage occurs nearer the bark.

Ring Stone: Same as "Voussoir." -- A stone or block in the shape of a truncated wedge which forms part of an arch ring.

Rip Saw: A saw having teeth with small set and large rake used for sawing along the grain of timber.

Riprap: A facing of stone, concrete, or planks placed on the bank slope of a stream or around a pier to prevent erosion.

Rise: The vertical distance between two treads in a stairway.

Rise of an Arch: The vertical distance from the springing line to the highest point of the intrados.

Risers in Moulds: An excess of metal above the casting proper. Its purpose is to keep the mould full while the metal is hardening.

River Gravel: Smooth, rounded stones, varying in size from sand particles to pebbles several inches in diameter.

Rivet: A short iron or soft steel rod with a head at one end. It is heated and put into a proper hole, and the other end is hammered down until a suitable head is formed.

Rivet Cutter: A hand tool, similar to a cold-cut but with edge sharpened on a more obtuse angle, used for cutting off the heads of driven rivets.

Rivet Forge: A small forge used for heating rivets.

Rivet Hammer: A pneumatic or hand hammer for driving rivets. Also a light engineer's hammer for testing the tightness of rivets after driving.

Rivet-hole: The hole through which a rivet is driven or to be driven.

Rivet Rod: A bar of soft iron or steel from which rivets are made.

Rivet Set: A tool for shaping the heads of rivets. Often called a "Rivet Snap."

Rivet Snap: A tool used for forming the head of a rivet."

Rivet Steel: A soft steel from which rivets are made,

Rivet-stem: The shank or that portion of the rivet under the head.

Rivet Tongs: Tongs used by field riveters for throwing and placing hot rivets.

Riveted Girder: A girder built of plates and angles riveted together throughout.

Riveted Joint: A joint in which the parts are held together by rivets or splice plates and rivets.

Riveted Truss: Any truss having its main members riveted together.

Riveter: One who drives rivets. A riveting machine.

Riveting: The fastening of plates or parts together by means of rivets.

Riveting Burr: A washer upon which a rivet-head is swaged down.

Riveting Gang: A gang that does the riveting.

Riveting Gun: A riveting hammer.

Riveting Kit: A kit of tools for driving field rivets.

Road-bed: In railroading the finished surface of the roadway on which the ballast and track rest. In highways that of the roadway which receives either the concrete base or the broken stone.

Road Roller: A heavy steam or horse roller used in the construction of macadamized roads and pavements.

Roadway: That part of the road over which the vehicles pass.

Rock Drill: Any drill used for quarrying rock.

Rock Faced Dressing: The facing on stonework left rough as it comes from the quarry. It may be drafted or pitched so as to reduce projecting points on the face or to given limits.

Rock Movement: A slipping movement of a ledge of rock, usually caused by water in the horizontal seams.

Rock Shaft: A shaft which makes part of a revolution each way instead of rotating continuously in the same direction.

Rock Work: Rock excavation. Also used for "Masonry."

Rock Work Dressing: Same as "Rustic Dressing."

Rocker: A casting or built-up steel frame fastened to the end of a truss or column to permit of a slight rotation.

Rocker-arm: An arm on a rock shaft, as in the valve mechanism of a steam engine.

Rocker Bearing: A bearing, or support, for solitary trestle bents or cantilever spans which permits of a slight rocking with the changing position of the live load and with variations of temperature.

Rocker Bent: A bent generally of steel, though sometimes of timber, hinged at either one or both ends so as to provide for the expansion and contraction of the span supported.

Rocker End: The end of a truss or column resting on a rocker.

Rod: A long, round piece, strip, or bar of metal. A surveyor's tool for finding the difference in elevation between two points, used in connection with a level. As ordinarily constructed, it consists of two flat strips of wood, arranged to slide upon each other and having the exposed faces graduated into feet and tenths, or in some cases, feet, inches, and fractions of an inch.

Rodman: The man in a level party who carries and manipulates the level rod.

Roll Rack: A rack on which a pinion works.

Rolled Beam: A metal beam made by a rolling process.

Rolled Channel: A channel which is rolled in one piece, in contradistinction to the built channel.

Rolled Iron: An iron that has passed through the rolls.

Rolled Pile: A type of concrete pile in which concrete is rolled up in a wire mesh, to which longitudinal reinforcing rods are attached. The mesh takes the form of a spiral during the process, which is continued until the desired size and shape are secured.

Rolled Steel: Steel that has been cast into ingots and then passed through a succession of rolls until the desired final shape is obtained.

Roller: Any short, round bar put under an object to facilitate its movement.

Roller and Thimble Chain: A chain in which the links are connected by means of rollers and thimbles.

Roller Bearing: A shoe or plate resting on rollers which in turn rest on a base casting at the expansion end of the span.

Roller-bearing Bascule: A type of bascule which has a fixed axis of rotation and which is supported on friction rollers to reduce the resistance to turning.

Roller Box: An iron or steel box holding rollers for a bridge shoe.

Roller Frame: Same as "Roller Box."

Roller Plate: A bed plate on which the rollers of the expansion end of a truss rest.

Rolling Bascule: A bascule which retreats as it rises by having a cylindrical surface roll on a plane. In some types both surfaces are toothed.

Rolling Draw Bridge: Same as "Pull-back Draw Bridge." -- A movable span which retreats longitudinally to allow the passage of vessels.

Rolling Friction: The resistance offered by a surface to another surface rolling over it.

Rolling Lift Bridge: A bascule bridge in which the moving arm rolls on a plane or upon friction rollers.

Rolling Load: Same as" Moving Load." -- An advancing load on a structure.

Rolling Mill: Same as "Mill." -- A machine for rolling plates, shapes, rails, etc. The plant where steel shapes etc., are rolled.

Rolling Planimeter: A planimeter in which the tracer arm is pivoted to a short bar mounted on rollers.

Rolling Stock: All of the various classes of cars and engines used on a railroad.

Rolls: A machine consisting of several rollers, mounted in a frame, having intermeshing gears producing a positive motion; used in shaping steel ingots into bars, beams, angles, etc.

Roman Cement: A natural cement of about the same characteristics as the Rosendale, supposed to have been used by the early Romans.

Roof Truss: Any truss used in supporting a roof.

Root of Tooth: The base of the tooth where it joins the rim of the wheel.

Rope: Strands of wire, hemp, cotton, flax, etc., twisted in a smooth, flexible cord of at least one-half inch in diameter.

Rope Bridge: A suspension bridge in which ropes are used for cables.

Rope Clamp: A device consisting of a pair of clamping jaws carrying a ring and hook used for securing or attaching the end of a rope to some object.

Rope Guard: A mechanical device for ropes running over sheaves or through pulley blocks.

Rope Lashing: See "Lashing."

Rope Sling: A sling made of rope.

Rose Drill: A drill with a cylindrical cutting face.

Rose Jet: A jet of water issuing through a nozzle having one central opening at the end and five openings around the sides with their axes inclined about forty-five degrees to that of the axis of the nozzle.

Rosendale Cement: A hydraulic, natural cement that is light, quick-setting, and has an ultimate tensile strength of about one-half that of Portland cement. It comes from Rosendale, N. Y. The term has been improperly applied as a synonym for natural cement.

Rosette: An ornamental device resembling a rose in bloom.

Rot: Decay, decomposition.

Rotary Crane: A crane having a jib swinging in a complete circle.

Rotary Furnace: A form of puddling furnace in which the hearth is made to rotate in a vertical or a horizontal plane in order to assist in removing the carbon.

Rotary Pump: A pump that lifts water by the rotary motion of its parts.

Rotating Draw: Same as "Revolving Draw Bridge."

Rotating Drill: A drill having a rotating motion instead of a churning motion.

Rotation: Turning around on an axis or centre. Rotary motion.

Rotten Knot: A knot in timber softer than the surrounding wood.

Rough Ashlar: Ashlar blocks in which the faces are left rough. This term is also used, rather illogically, for squared range-masonry.

Rough Dressing: Same as "Rock Faced Dressing."

Rough Finish: The finish which is left by the original forms, moulds, etc.

Rough Pointed Dressing: A type of stone dresing which presents an irregular surface, but has no projection exceeding a half inch from the surface of the pitch face.

Rougher: A man or a machine that does the preliminary work or roughing out of an object.

Round Knot: A knot in timber which is oval or circular in form.

Round Pile: A pile having a round cross-section.

Rounds: Round bars in the bracing system of a highway bridge. The rungs of a ladder.

Row Lock Bond: A bond in an arch of concentric rings, formed by laying the bricks in each ring as stretchers leaving only the mortar to unite the several rings.

Rowlock Bond: See "Row Lock Bond."

Rubbed Dressing: Same as "Plain Dressing." -- In stonework, a facing rubbed smooth to remove tool marks.

Rubbed Stone: Same as "Rubbed Dressing."

Rubber: A man or a machine that smooths stone. An elastic gum.

Rubber Hose: A hose in which the covering is rubber or a composition of rubber and fabric.

Rubber Packing: Packing made of rubber, usually with cloth backing or insertions. Put up in sheet form or in flexible bars.

Rubble: Rough, broken, one-man-size stone used in rubble masonry.

Rubble Course: A course in which rough stones are leveled off at specific heights to an approximately horizontal surface.

Rubble Masonry: Masonry composed of unsquared stone. It may be coursed or uncoursed rubble.

Rubble Work: Same as "Rubble Masonry."

Ruff: An annular ridge formed on a shaft or other piece, commonly at a journal, to prevent motion endwise.

Rule: A flat, straight stick or strip of metal graduated into linear units for convenience in measuring or laying off distances.

Rule Joint: A pivoted joint similar to a hinged joint.

Run or Runway: A line of planks laid down for wheeling or walking over. Used by constructors.

Run-off: The water which flows from a drainage basin.

Rundle: The step of a ladder. See "Rounds."

Rung: The round or step in a ladder.

Rung-head: The upper end of a floor timber.

Runner: In foundry practice, the channel through which molten metal is run into the mould.

Running Block: A movable block in a system of tackles.

Running-expense: Expenditures incurred during the operation of the plant or structure only. They are equal to the sum of operation and maintenance outlays.

Runway: A passageway. Also see "Run."

Rupture: To break apart. The act of breaking apart.

Rupture Line: The line along which rupture occurs or would occur if the piece were tested to destruction.

Rust: An oxidization of a metal.

Rust Cement: Iron turnings treated with acid and used to bed metal plates. Not permissible in good engineering practice.

Rust Joint: A joint between pieces of metal made by a rusting process. Not permissible in good bridge engineering practice.

Rustic Dressing or Rusticated Dressing: A form of stone facing that projects beyond the arrises, which are beveled or drafted. The projecting face may be dressed in any desired form.