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Glossary of Bridge Terminology



Cable: A heavy rope, chain, or twisted wire rope. An aerial or underground conductor of electricity with insulating covering. The suspending portions of a suspension bridge.

Cable Clamp: A clamp consisting of a U bolt, saddle, and two nuts, used on cables.

Cable Clips: A device for hanging an electric cable to a supporting cable, or for attaching anything to a cable.

Cable Hoist: A hoist in which cables winding about a drum or drums are used to lift the load.

Cable Splice: A joint or connection made of two ends of a cable. The weaving together of the ends of two ropes or cables.

Cable-way: An underground passage carrying a cable or cables.

Cage: A framework to confine a ball valve within a certain range of motion. A wire guard placed in front of a suction opening to allow liquids to enter, but to prevent the passage of solids of objectionable size. A skeleton framework of any kind surrounding any object.

Caisson: A sunken panel in a coffered ceiling. A watertight box or casing used in founding and building structures in water too deep for cofferdams.

Caisson-disease: Same as "Bends." -- A pneumatic caisson disease, due to the abnormal air pressure. It is a species of temporary paralysis.

Calculated Horsepower or Commercial Horsepower: Horsepower calculated from the area of the piston. Sometimes only a fraction of the real horsepower.

Calculation Paper: A paper with quadrille ruling used by computers, because of its convenience in drawing sketches and in arranging computations in a tabular form.

Caliber: The inner diameter or bore of any tube.

Caliper: An instrument, consisting of two adjustable moving parts, which is used to measure the outside or inside diameter of a cylindrical body.

Caliper Compass: A caliper made similar to a drawing compass or dividers with curved legs for measuring inside and outside diameter.

Caliper Gauge: A tool or standard for measuring with great accuracy.

Caliper Rule: An outside caliper formed by a rule having a graduated slide at one end.

Caliper Square: A rule carrying two cross-heads, one of which is adjusted slightly by a nut, the other being movable along the rule.

Calk, or Caulk: To drive oakum or similar substances into seams of boxes, boats, barges, caissons, etc., in order to keep out the water. Also to copy a map by tracing.

Calked Rivet: A rivet which has not been properly driven so as to fit tightly in the hole, but to which a seeming tightness has been given by turning the edge of the head under with a cold cut or similar tool.

Calking-butt: An open-end joint between planks in the side of a timber box or caisson.

Calking-iron: A dull chisel for calking cofferdams and caissons.

Calking Mallet: A mallet used in driving calling irons.

Calking Metal: A soft lead-rust mixture put in calking grooves. Sometimes Portland cement is used for such purpose.

Calking Nail: A pointed hand-tool used in metal calking.

Calking Tool: A tool used for the process of calking.

Calyx Core Drill: A drill for making borings in earth strata. It consists of a revolving shank having a hollow steel bit under which chilled steel shot are made to travel. The rotation and pressure cause the shot to mill away the rock leaving a portion of it sticking upward inside the drill. At suitable intervals the core is broken off and brought to the surface for examination.

Cam: An eccentric; a piece fixed upon a revolving shaft in such a manner as to produce a reciprocating motion in a member making contact with it. Also called a wiper.

Cam Shaft: A shaft on which a cam is mounted.

Camb: Same as "Cam."

Camber: The upward curvature of a span above its nominal position.

Camber Blocks: Blocks of wood or wedges of steel used during erection to give camber to a span, and so placed as to be easily removed when swinging it.

Camber Jack: Any special jack used for putting the initial camber in a truss in place of wooden wedges.

Camber-slip: A slightly curved guide and support of wood used as centering in laying straight arches of brick.

Cambering Machine: A machine used for bending beams to a curve in a vertical plane.

Camel-back Top Chord: A top chord that is broken or deflects at two or, at most, three points.

Camel-back Truss: A truss having a broken outline for the upper chord taking the humped shape of a camel's back. See Figs. 22ee and 22ff.

Fig. 22eeFig. 22ff

Canal: An artificial waterway for navigation. A duct.

Cancellation: A system or arrangement of the web members in a truss.

Candle-power: The standard unit of luminous intensity equal to that given by the burning of a standard spermaceti candle at the rate of one hundred and twenty grains per hour.

Candle-wick Packing: A packing made of cotton fibres and put up in the form of a loosely-woven cord.

Candle-wicking: Wicks for candles; used sometimes for calking purposes.

Cant: To turn over anything. The hook on a cant-hook for rolling timbers. To set at an angle; to tilt from a horizontal line.

Cant Dog: Same as "Cant Hook."

Cant Hook: A wooden bar or lever with an iron hook hinged at the end, used for turning over heavy timbers.

Cantilever: A bracket of stone, metal, or wood projecting from a supported beam or wall. Also see "Cantilever Bridge."

Cantilever Arch Truss: A cantilever truss having the shape of a portion of an arch.

Cantilever-arm: The projecting arm in a cantilever bridge.

Cantilever Beam: A beam supported at one end only.

Cantilever Bracket: A bracket cantilevered out from another member.

Cantilever Bridge: A structure at least one portion of which acts as an anchorage for sustaining another portion which projects beyond the supporting pier.

Cantilever Crane: A crane, in which the weight to be lifted is balanced by a heavy mass of material such as stone blocks or pig iron. It is generally capable of being rotated, the rear end being supported by a circular track.

Cantilever Span: That span of a cantilever bridge, which contains a suspended span and either one or two cantilever arms. In some cases the suspended span (most improperly) is omitted, making the cantilever span consist of two cantilever arms only.

Cantilever Truss: A truss overhanging its support at one end and anchored down at, the other.

Canvas Hose: A hose in which the covering is canvas.

Cap: A covering of metal or of tarred canvas at the end of a rope to prevent fraying. The upper part of a journal box. The terminal section of a pipe having a plug at the end. A horizontal timber beam resting on and joining the heads of a row of piles or timbers. The top of a column. The part connecting a pump-rod with the working beam. Also a container for an explosive used in blasting. To cap or to cover.

Cap Piece: A rectangular timber covering the top of a row of squared timber posts.

Cap Plate: The top plate on a steel column or post. It generally supports a load.

Cap Screw: A screw which has a square or hexagonal head larger than the shank of the screw, thereby providing a shoulder for bearing. It is turned with a wrench.

Cap Sill: A sill placed on piles.

Cape Chisel: A hand tool made from a short steel bar having one end flat and the other tapering to a blunt edge sharpened at an obtuse angle to prevent breaking. Used in connection with a hand hammer for chipping cast iron. It differs from a cold chisel in having a narrower blade with more stock behind it.

Capital: The upper part of a column, pilaster, or pier. The money value set on the property or assets involved in a business enterprise.

Capitalized Total Cost: A sum of money that includes the first cost of a structure, plant, etc., plus an amount the interest on which would cover the annual expenditures for operation, maintenance, and repairs.

Capitalized Value: Same as "Present Worth." -- The present worth of a sum of money due a number of years hence is that principal which at compound interest will produce the desired amount at the end of the given time. The present worth of a sinking fund is equal to the present worth of the amount of the fund, and is the sum of the present worths of the deposits.

Capping: A general term for a series of caps in a structure. Putting a timber cap on a row of piles.

Capstan: An apparatus working on the principle of the wheel and axle, used for raising weights or applying power.

Capstan Bar: One of the levers by which a capstan is turned.

Capstan Head: That portion of the capstan which contains the holes for receiving the ends of the capstan bars.

Capstone: The uppermost or finishing stone of a masonry structure.

Car: A conveyance or receptacle running upon rails.

Carbon Steel: Ordinary steel which contains no other alloying element than the usual amount of manganese. The term is generally employed in contradistinction to nickel steel or other alloy steel.

Carborundum: A combination of silica and carbon made in an electric furnace, used in place of emery as an abrasive material.

Carborundum Brick: A brick of carborundum with serrated edges made in an electric furnace and used for smoothing or polishing.

Carpenter's Level: A plummet attached to a wooden T having a line through the attachment of the plumb-line perpendicular to the edge of the wood. Also a "Spirit Level."

Carpenter's Line: Any light cord or string stretched between nails, used by carpenters to line up work.

Carriage: Any part of a machine that carries another part. A drain. The timber frame which supports the steps of a wooden stair.

Case-hardened Steel: Steel with the outer skin hardened by heating, after being made into shape, with some such animal substance as grease, bone, hoofs, or horns.

Case-hardening: Converting the outer surface of iron into steel by heating while in contact with charcoal.

Case Steel: The outside skin on steel caused by case hardening.

Casing: A wooden tunnel for the powder-hose in blasting. The outside pipe which is used in making borings. A covering.

Cast: To make a casting out of molten metal. A small brass funnel at the end of a mould for casting pipes.

Cast Gears: Gears made by casting and not trimmed.

Cast Iron: Iron as it comes from the smelter containing usually from two and a half to four per cent of carbon.

Cast-iron Pipe: Pipe made of cast iron.

Cast Lead: Lead which has been cast in a mould.

Cast Steel: Steel that is cast into shape directly from the furnace instead of being cast into ingots and rolled or melted.

Caster Wheel: A wheel having its axle held in a stock or frame that turns about an axis perpendicular to its own.

Casting: The act or process of founding. That which has been cast by pouring molten metal into a mould.

Catch: Any mechanical contrivance used for stopping, checking, or preventing motion.

Catch-basin: A reservoir placed at the outer end of a sewer connection to intercept the flow of water in a gutter.

Catch-drain: Same as "Catch-water."

Catch-water: A channel or drain running along sloping ground or pavement to catch and carry away the water.

Catch-work: Same as "catch-water."

Catchment Area: Same as "Drainage Area." -- The area drained by a stream or streams.

Catenary: A curve formed by a flexible, inextensible cord or chain of uniform weight per unit of length, hung at two points and supporting its own weight alone.

Catenary Arch: An arch which takes the form of an inverted catenary.

Catenary Curve: Same as a "Catenary."

Cattle Guard: A device consisting usually of sharp-edged, parallel bars placed in a railroad track to prevent stock from getting on the right-of-way.

Causeway: A raised footway or road.

Caustic Lime: Same as "Quick Lime." -- The commercial lime, or a calcium oxide, which has not been hydrated.

Cedar Block: A paving block, usually round, made of cedar.

Cell: A unit of an electric battery consisting of two plates of different substances, usually zinc and carbon, immersed in an exciting liquid held in a jar, so as to set up an electric current.

Cement: Any composition which at one temperature or one degree of moisture is plastic, and at another condition of temperature or moisture is tenacious. A mortar which hardens. To unite by cement.

Cement Bin: A bin, usually at the cement mills, in which cement is stored for aging.

Cement Brick: A brick made out of cement and sand.

Cement Briquette: A briquette made of cement and water for testing the tensile strength of the cement.

Cement Finish: A finish made by using a cement coating.

Cement Floor: A floor having a grouted wearing surface.

Cement Gun: A barrel or nozzle through which grout is forced by compressed air.

Cement Kiln: A rotating furnace having a slight slope, receiving the pulverized, raw material at its upper end and gradually working it toward the lower end where the fire is located.

Cement Mill: A factory where cement is manufactured.

Cement Mortar: A mortar made from cement.

Cement Mould: A mould used in forming cement mortar for testing purposes.

Cement Needle: A small round rod weighted with a ball, used to determine the activity of cement.

Cement Pile: Same as "Concrete Pile."

Cement Stone: Any rock having the necessary alumina, silica, and lime content which can be converted into cement under proper treatment.

Cement Testing Machine: An apparatus for testing the strength of cement-generally for determining the tensile strength, but occasionally for finding the resistance to compression.

Cementation: The process of converting wrought-iron into steel while heating it in contact with charcoal. The act of cementing; the act of uniting by adhesive substances.

Cemented Steel: Steel produced by impregnating bars of wrought iron or soft steel with carbon at a temperature below the melting point.

Cementing Furnace: A furnace used in the process of cementation.

Center: See also "Centre" and words beginning "Centre."

Center of Mass: That point at which the mass of a body may be considered as concentrated without disturbing its equilibrium; the center of gravity or the center of inertia of a body.

Centering: Same as "Arch Centre." -- A temporary structure for supporting an arch while in the process of construction.

Centering Casting: A casting used to bring a movable span to exact position when seated.

Centre: The middle or reference point of an object.

Centre Bearing: A term applied to swing spans to indicate that the dead load support is near the axis of the pivot pier instead of near the periphery thereof.

Centre Bearing Draw: A swing span supported on a central pivot.

Centre-bearing Turntable: A turntable having a centre pivot for supporting the load during operation.

Centre Drill: A drill for making a central hole, as in a shaft.

Centre Line: A line connecting the centre points of anything.

Centre of Buoyancy: The centre of gravity of the water displaced by any wholly or partially submerged body.

Centre of Displacement: Same as "Centre of Buoyancy."

Centre of Gravity: That point in a body about which the weights of all the various portions balance. It is found experimentally by balancing on a knife edge.

Centre of Gyration: A point in a revolving body such that if all the matter of the said body could be collected there, the body would continue to revolve with the same energy as when its parts were in their original places.

Centre of Inertia: That point in a body which is so situated that the force or combination of forces requisite for producing motion in the said body, or bringing it to rest or changing its motion in any way, is equivalent to a single force applied at the said point. This point coincides with the center of gravity of the body.

Centre of Magnitude: That point in a body which is equally distant from all the similar external parts of it.

Centre of Mass: See "Center of Mass."

Centre of Moments: The point about which a body tends to rotate. Often a point arbitrarily chosen for convenience in determining the resultant moment of a system of forces.

Centre of Motion: Same as "Centre of Rotation."

Centre of Percussion: That point of a suspended body such that if a blow be struck thereon no reaction will be developed at the point of suspension. This point is identical with the centre of oscillation and is located at such a distance from the point of suspension that if the whole mass of the body were concentrated there, the time of oscillation would remain unchanged.

Centre of Perspective: The point which is collinear with every pair of corresponding points of two figures in perspective.

Centre of Pressure: The point at which the resultant of the pressures on a surface acts.

Centre of Resistance: The point of application of the resultant of all the resisting forces.

Centre of Rotation: The point of a rotating body which remains at rest while all the other points revolve around it.

Centre of Stress: The point of application of the resultant of the stresses on a section.

Centre of Symmetry: The intersection of the axes of symmetry.

Centre Pin: The pin on which the needle of a compass oscillates.

Centre Post: An intermediate post on the longitudinal centre line of a timber bent.

Centre Punch: A marking punch that makes a small indentation in steel so as to locate the centre for a rivet-hole.

Centre Valve: A four-way valve.

Centrifugal Force: The reaction of a body, due to its inertia, against that force which is causing it to deviate from a straight-line motion and to travel in a curved path. A fictitious force apparently balancing the central force.

Centrifugal Load: The horizontal load on a structure produced by the centrifugal reaction caused by the velocity and mass of a moving train as it passes around a curve.

Centrifugal Pump: A rotary pump in which a revolving fan creates a partial vacuum in its chamber, causing the water to rise until it comes in contact with the swiftly moving vanes by which it is expelled through the discharge pipe.

Centrifugal Stress: A stress due to the centrifugal reaction of a live load moving in a curve. Any stress acting in an outward direction from the centre of a body.

Centripetal Force: A force pulling a body toward the centre of rotation.

Centripetal Stress: Any stress acting toward the centre of a body.

Centroid: The centre-of mass, or centre of gravity. The point of application of the resultant of a system of stresses or forces.

Chain: A connected series of links of metal serving the purpose of a band, cord, rope, cable, or measuring line. To tie or fasten with a chain.

Chain Bearer: That one of the staff in a survey party who carries and handles an engineer's or surveyor's chain or tape. The chainman.

Chain Blocks: An endless chain running over two differential pulleys. Used for hoisting.

Chain Bond: A bond formed by binding a chain, a bar, -or a heavy scantling into masonry.

Chain Bridge: A suspension bridge in which chains are employed instead of the usual cables.

Chain Cable: A very heavy linked chain used in place of a steel wire cable in bridgework.

Chain Coupling: A hook connected to the end of a chain for the purpose of connecting it with another chain or object.

Chain Dog: A lumber chain having on each end a hook to be driven into logs that go to make up a raft.

Chain Drive: A mechanism consisting of a chain or chains for transmitting power.

Chain Gear: A device for the transmission of motion by means of a chain engaging the cogs or sprockets of a wheel.

Chain Hoist: A hoist in which chains are used for lifting loads.

Chain Hook: A hook which grips a link of a chain, and serves as a cable stopper.

Chain Pulley: Same as "Chain Wheel.".

Chain Pump: A pump employing an endless chain provided at intervals with buckets or with flat valves or disks working in a tube, used for raising water short distances. It is an uneconomic device.

Chain Riveting: A term applied to riveting where the rivets in the second or succeeding rows are placed directly back of those in the first row or preceding rows.

Chain-smith: One who makes chains.

Chain Tape: A thin steel ribbon graduated on one side in feet and on the other side in surveyor's links.

Chain Wheel: A wheel having projections or indentations on its face for the purpose of engaging the links of a chain.

Chainman: Same as "Chain Bearer."

Chair Casting: A casting used to support the end of a rail.

Chalk Line: A cord rubbed with chalk, used for marking lines on surfaces by being held taut and snapped with the fingers. Also the mark left by such a process.

Chamber: The recess in an axle box designed to hold the lubricant. A compartment or an enclosed space, as the chamber in a caisson.

Chamfer: To bevel or sharpen to a blunt edge.

Chamfered Groove: A triangular groove.

Chamfered Joint: Same as "Miter Joint." -- A special case of a beveled joint in which the contact surfaces make angles of forty-five degrees with the axes of their respective parts.

Channel: The deepest part of a river, bay, or stream; usually that part available for navigation. The trough used to conduct molten metal from the furnace to the moulds. To form or cut a channel. A structural or rolled steel shape used in bridge building and in other steel constructions.

Channel Column: A column made up of two channel-irons laced or stayed.

Channel Iron: Same as "Rolled Channel." -- A channel which is rolled in one piece, in contradistinction to the built channel.

Channel Span: The span which bridges the deepest part of a river or that part most accessible for navigation.

Channel Strut: A strut built up of channels.

Channeling: Making a new channel. Grooving or cutting in quarrying stone. A system of channels or gutters.

Channeling-machine: A machine for cutting grooves or channels when quarrying stone.

Characteristic Curve: A curve which shows the relation existing between certain features or properties of a machine or substance.

Charcoal Iron: Iron made in a furnace where charcoal is used as a fuel.

Charcoal Steel: Steel in which charcoal is used for a fuel in its production.

Charred Pile: A wooden pile having its lower end charred in order to preserve it.

Chats: Tailings from mills in which zinc and lead ores are treated.

Check: A small crack in wood due to seasoning, or in concrete or mortar due to drying.

Check Nut: An extra nut which is screwed on a bolt tight against the first nut to prevent the latter from working loose.

Check Valve: A valve arranged to permit a flow in one direction only, thereby preventing the return of the fluid.

Check Washer: A washer devised to prevent a nut from turning.

Checkered Plate: A cast steel or iron plate having square, flat projections suggestive of a checkerboard. Its function is to give a foothold for horses.

Chenoweth Pile: A rolled concrete pile designed by a Mr. Chenoweth.

Chicago Boom: An erector's hoisting apparatus, consisting of a timber or steel boom, without a mast, having a goose-neck casting on the lower end working in a saucer block on a temporary sill, and held in position by blocks and tackle attached to other parts of the structure.

Chilled Castings: Castings which are rapidly cooled during solidification.

Chilled Iron: Iron that is surface-hardened by sudden cooling at the time of casting.

Chinese Anchor: A. rectangular box filled with rocks, used for anchoring in swift currents. A sling, or bridle, is attached tothe box, and to this a float is fastened.

Chinese Capstan: A differential windlass with its axis vertical, used for hoisting or hauling.

Chinese Windlass, or Differential Windlass: A windlass having an axle or barrel with different diameters, so that the rope winds up on the larger and unwinds from the smaller, the difference between the two motions resulting in a slow lifting of a heavy load.

Chisel: A hard tool consisting of a sharp-ended blade designed to cut under the impulse of a blow.

Chisel Bar: A heavy hand bar with a chisel edge on one end.

Chisel Draft: A tool used for drafting stone. The cut in stonework made by such a tool-generally at the edges of the stones.

Chiseled Dressing: Same as "Boasted Dressing." -- A finish in stonework wrought with a chisel or narrow tool.

Chock: A block, a piece of wood, or other material specially prepared and generally wedge-shaped, used to prevent movement by insertion under wheels, etc. To secure by putting a chock into or under a moving object, or one that is likely to move.

Chock-a-block: Jammed. Said of a tackle when the blocks are so close hauled as to prevent further motion.The condition of a set of blocks and tackle when the blocks can go no closer together. Called also "block and block" and "two blocks."

Chock Block: A device for stopping the motion of the traveling wheels of a portable machine.

Chord: That portion of a truss the main function of which is to resist bending on the span.

Chord Boring Machine: A boring machine used in bridge shops for boring pin-holes in chords.

Chord Head: The enlarged head of a chord bar through which the pin passes.

Chord Packing: The arrangement of all the members of a pin-connected chord.

Chord Pin: Any pin on, or very near, the centre line of a chord.

Chord Pitch: The distance between centres of teeth, measured on the chord of the pitch circle of a gear.

Chord Splice: A splice made in a chord of a truss.

Chord Stress: Any stress which exists in a chord of a truss.

Chord Stringer: A chord length subjected to bending as well as to direct stress.

Chrome Steel: Steel that usually contains two per cent of chromium and from eight tenths of one per cent to two per cent of carbon. It is very hard and has a high elastic limit.

Chuck: A device attached to a revolving shaft or mandrel of a lathe for holding the object to be turned.

Churn Drill: A steel bar about eight feet long having its ends flattened and sharpened for drilling into hard strata.

Chute: An inclined trough or pipe along which substances are slid from a higher to a lower level. Also spelled "Shoot."

Cincture: A ring, list, or fillet at the ends of a column serving to separate the shaft from the capital or the base.

Cinder: Slag, especially that produced from making pig iron in blast furnaces. Ordinarily the residue of burnt coal, being the impurities thereof fused together to form lumps.

Cinder Concrete: A concrete composed of cement, sand, cinders, and water.

Cinder Pig: A pig iron made from smelting top cinder or bulldog with ores.

Cinder Pocket: A pocket made in rolled steel by rolling cinders into the metal. These may either remain or drop out of the rolled product, leaving holes or pockets.

Cinematics: Same as "Kinematics." -- That branch of the science of mechanics which treats of the motion of bodies without reference to the cause or force producing it.

Circle: A graduated plate on a transit.

Circuit: The arrangement by which an electrical current is conducted between the two poles of a generator or battery.

Circuit-breaker: A device for automatically opening an electric circuit.

Circular Arch: An arch which takes the form of a portion of a circle.

Circular File: A small file having a circular cross section.

Circular Girder: A girder built in the shape of a circle.

Circular Pitch: The distance between centres of teeth, measured on the pitch circle of a gear. Also called the pitch of the tooth.

Circular Saw: A thin circular plate of steel, with teeth cut in the edge, mounted on a shaft and rotated at a high speed.

Clack Valve: A valve hinged at one end so as to permit the flow of the liquid in one direction only.

Clam Shell Bucket: A dredging bucket composed of two curved leaves hinged about a point at their top and so arranged as to open or shut at the will of the operator.

Clamp: An instrument or tool consisting of two movable parts that can be drawn together by a screw or other suitable mechanism, used to fasten two objects together by pressure. One of a pair of movable cheeks on a vise. To fasten by pressure.

Clamp Drill: A drill having a clamp to hold it to the work.

Clamp Iron: Same as "Clamp."

Clamp Screw: A clamp operated by a thumb-screw.

Clam-shell Bucket: A dredging bucket composed of two curved leaves hinged about a point at their top and so arranged as to open or shut at the will of the operator.

Clam-shell Dredge: A dredge using a clam-shell bucket attached to a hoisting apparatus like a derrick.

Clap-boards: Short, thin boards, shingle shaped, and used instead of shingles.

Clapper Valve: A form of check valve used in pneumatic work to prevent the escape of air from the working chamber when the compressor shuts down.

Classification: The distribution into sets, sorts, or ranks.

Classify: To arrange in classes, sorts, or ranks according to some method founded on common characteristics in the objects so arranged.

Claw: A split provided at the end of a bar or a hammer for taking hold of the heads of nails, spikes, or bolts so as to withdraw them from wood.

Claw Bar: A hand bar with a bent, claw-shaped point for drawing spikes from railway ties or sleepers.

Claw Coupling: A coupling in which the claws of one part fit into the recesses of the other part with a little amount of play; so that when the shafts are out of line, the coupling will accommodate itself to the obliquity without overstressing the shafts

Claw Hammer: A carpenter's hand hammer having a poll on one end of the head and a claw on the other.

Claw Wrench: A wrench with a claw end.

Clawback: A balk or a beam, used in making floating bridges.

Clay-daubed: Cracks filled with clay, as is sometimes done in forms for concrete.

Clay Puddle: Explained under "Puddle."

Clear-headway: The vertical distance from the upper surface of a floor to the lowest part of the overhead bracing. It is the measure of height of the tallest vehicle that could pass through the bridge. Also the vertical distance from the water surface or the ground to the lowest part of the superstructure.

Clear Roadway: The horizontal distance, measured perpendicularly to the plane of the trusses, between the inner edges of the batter braces. Sometimes measured between the faces of curbs or guard rails.

Clear Span: The distances between the two inside faces of the supports of a span.

Clear Span Length: Same as "Clear Span."

Clear Waterway: The horizontal distance over the water, measured perpendicularly to the centre lines of adjacent piers or fenders between the inner edges thereof.

Clearance: The space allowed for the passage of any vehicle or craft through or near a construction. The additional space allowed for the fitting together of members over that nominally required, in order to provide for slight irregularities of workmanship or materials.

Clearance Diagram: A diagram used in bridge designing showing the horizontal and vertical clearances in a structure.

Clearance Line: A line on a diagram showing the minimum clearance allowed.

Cleat: A piece of wood or iron with projecting prongs, used for belaying or winding ropes on so as to make them fast.

Cleave: To part or divide by force. To rend asunder, as to cleave wood or rock.

Cleveland Hammer: One of the numerous makes of air riveting hammers.

Clevis: A connecting iron bent into the form of a horseshoe, stirrup, or letter U. A link in a chain shaped like the letter U. An adjusting piece for bridge members of varying length.

Clevis Pin: A pin used to connect a clevis with a plate.

Click: Same as "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.

Clinch: A hold-fast. To bend over a piece of projecting metal so as to make an attachment. To fasten firmly.

Clinch Bolt: A bolt with one of its ends designed to be bent over to prevent withdrawal.

Clinker Brick: Brick that forms the tops and sides of the arches in a brick-kiln and consequently is directly exposed to the fire. Being overburned and partially vitrified, clinker bricks are hard, brittle, and weak.

Clinton Wire Cloth: A form of wire netting having nearly square meshes of large size with the longitudinal wires heavier than the transverse ones, used for reinforcing concrete.

Clip: A fastening. The hinged yoke on top of the Y's in a spirit-level.

Clip Angle: A short attaching angle that takes a portion of the stress of any main member; also termed a "Lug-angle."

Clip Pulley: A wheel which has on its face a series of grips or clips for holding the band or wire rope that passes over it.

Clipping Hammer: A chisel-edged hammer used for clipping stone, concrete, etc. Nowadays air hammers are so arranged that they can quickly be converted into clipping hammers.

Close-quartered Reamer: A pneumatic reamer having a cutting tool with a short shank, for working in restricted spaces.

Closed Column: A column that is boxed in, shutting out water and air, generally making the interior inaccessible for painting.

Closing Line: The last line or side of a polygon, drawn or surveyed, which encloses the area.

Closing Pile: The last pile driven for closing a gap.

Club Dolly: A dolly with a steel hammer head and an iron handle attached. The smaller end of the hammer head has a cup-like indentation for holding the rivet head. Usually a maul is held against the big end of the hammer head while rivets are being driven.

Club-footed Pile: Same as "Pedestal Pile." -- A patented pile formed by driving a steel shell into the ground to the required depth, putting in small quantities of concrete, and hammering them down so as to force the concrete into the earth beyond the point of the shell; thus enlarging the end and greatly increasing the bearing area. The shell is afterward withdrawn gradually, as the hole that it made is filled with concrete. If the shell were left in, the method would be far more satisfactory; as the shaft of the pile is liable to be seriously imperfect.

Cluster Bent: A bent having a cluster of piles driven at the places of heavy load concentrations.

Clutch: A movable coupling or locking or unlocking contrivance used for transmitting motion.

Clutch Coupling: A connection produced by means of a clutch.

Coarse Sand: Sand rejected by a number twenty sieve.

Cobblestone: A stone used in pavements, usually rounded like a pebble.

Cock: A faucet or turn valve consisting of a tapering plug having a transverse hole through it for the passage of fluids. This plug fits into a hole, or seat, having a corresponding taper, so that in one position the passage-way is blocked and in another position it is opened.

Cocked-hat: A coping projecting from the shaft of a pier above the'elevation of high water, used for enlarging the lower portion of the pier and its base, thereby increasing the stability and reducing the foundation pressure.

Coefficient: A constant factor in an algebraic expression.

Coefficient of Contraction: The ratio between the decrement of length, area of section, or volume and the original length, area of section, or volume. For temperature change, it is the same as the "Coefficient of Expansion." In hydraulics, it is the ratio between the area of the contracted section of a water-jet issuing from an orifice and the area of the orifice.

Coefficient of Elasticity or Modulus of Elasticity: The ratio of the direct stress per unit of area to the corresponding relative deformation, sometimes called Lineal Modulus. The numerical value is equal to the stress per unit of area in tension that would be required to double the length of a piece, were the material of which it is composed perfectly elastic. Also called "Young's Modulus."

Coefficient of Expansion: The amount of expansion per unit of magnitude of the substance, per unit of agent causing the effect. For example: the coefficient of lineal expansion of a bar of steel for an increase in temperature is the expansion per unit of length per degree of temperature.

Coefficient of Friction: A numerical quantity equal to the ratio of the frictional resistance to the normal pressure between the bodies; or, in other words, to the tangent of the angle of repose.

Coefficient of Impact: In bridge engineering, the ratio of the effect of a dynamically applied load to that of the same load applied statically, less unity. In other words, it is the factor nearly always less than unity, by which a static load effect must be multiplied in order to find the increment of the dynamic effect of applying the said load in a manner other than statically.

Coefficient of Lineal Expansion: See example under "Coefficient of Expansion."

Coefficient of Resilience: The amount of energy absorbed per unit volume of the body. This is affected by the class of deformation whether axial, bending, or torsional; hence there are three kinds of coefficients of resilience.

Coefficient of Restitution: The ratio of the total momentum after impact, to the total momentum before impact, in a system of colliding bodies.

Coefficient of Torsion: The angle of torsion produced in a wire of unit dimension by a force acting with unit moment.

Cofferdam: A temporary enclosing structure, practically watertight, from which the water is pumped, and within which masonry or concrete is placed in the open air.

Cog: A tooth, catch, or projection on the periphery of a wheel.

Cog Wheel: Same as "Gear."

Cohesion: The force that holds together the individual particles of a body.

Coignet, Beton: Same as "Beton-Coignet." -- A mixture of Portland cement, siliceous hydraulic lime, and clean sand mixed together with fresh water." Named after its French inventor, a Monsier Coignet.

Coil Chain: A straight-linked chain, in which the links are in the shape of two letters U joined at their tops.

Coil Friction Clutch: A friction clutch composed of a coil wound on a chilled cast-iron drum.

Cold Chisel: A hand tool made from a short, steel bar having a flat top and a tapering wedge-shaped end a trifle wider than the shank. Used for cutting metals while cold.

Cold-cut or Cold Cutter: A cold chisel mounted on a handle like a hammer. It is used with the application of a maul.

Cold Cutter: Same as "Cold-cut."

Cold-hammering: The act or practice of hammering metal when cold.

Cold-pressed: Pressed when cold. Applied generally to iron or steel.

Cold-pressed Paper: A drawing paper that has been pressed only on the felts, leaving it with a rough surface.

Cold-rolled: Rolled when cold. Applied generally to iron or steel.

Cold-rolled Shafting: Shafting on which the final rolling was done after the metal had somewhat cooled.

Cold Saw: A toothless, soft-iron disk rotating at a high speed, used in mills for cutting steel beams.

Cold-short: The condition of brittleness in steel when it is cold; caused by excessive phosphorus.

Cold-short Iron: Iron that is weak and brittle when cold, due to the presence of phosphorus.

Cold-short Steel: A steel that is very brittle when cold, usually due to an excess of phosphorus.

Cold Shut: The freezing over of the top surface of an ingot before the mould has been filled, due to an interruption of the stream of molten metal.

Cold-straightening: The process of straightening metal when cold.

Collapsing Bucket: A bucket which can be made to drop its burden by folding or collapsing.

Collar: A flat ring surrounding anything closely.

Collar Beam: A horizontal timber stretching from one to another of two rafters which meet at the top, and which are above the main tie-beam.

Collision Post: Same as "Collision Strut." An auxiliary post placed near the portal of a bridge to take up the shock of a derailed car or engine and prevent it from injuring the trusses.

Collision Strut: A strut placed against a point a little below the middle of the inclined end post of a bridge so that, in case of a derailment or a shifted load striking the said end post, the shock will be carried longitudinally to other members and not be taken up in bending by the said inclined end post.

Color: A generic term referring inclusively to all of the colors of the spectrum, white and black, and all tints, shades, and hues which may be produced by their admixture.

Column: A pillar or strut. A long member which resists compression.

Column Bent: A bent composed of columns and bracing in contra-distinction to "pile bent."

Column Crane: A crane built in the form of a latticed column with a curved overhang at, the top. Also called a "Tower Crane."

Column-foot: The base of a column.

Column Footing: A footing, or spread base, under a column.

Columnar Fracture: A cleavage into columns shown in the surfaces of the fracture.

Columnar Pile: A pile in which the bearing capacity, due to its point striking a hard stratum, depends chiefly on its action as a column.

Columnar Stroked: A form of dressing in masonry."

Columnar Stroked Dressing: A droved dressing in masonry in which the flutes are like those in a column.

Combination Bridge: A bridge constructed of timbers and steel or iron.

Combination Dolly: A double headed tool used for driving four different sizes of rivets. Usually balanced on a chain.

Combination Punch and Shears: An apparatus which does both punching and shearing.

Combination Wrench: A wrench having jaws to fit both nuts and pipes.

Combined Bridge: A bridge which carries both railway and highway traffic.

Combined Stress, or Compound Stress: A union of stresses such as direct stress and bending.

Commercial Horsepower: Same as "Calculated Horsepower."

Common Iron: The poorest quality of commercial iron.

Common Lime: Same as "Lime."

Common Logarithm: Same as "Briggs' Logarithm." -- A system of logarithms in which the base is ten.

Common Reamer: A tapered bit with fluted sides and having sharp cutting edges. [Also called "Fluted Reamer."]

Common Theory of Flexure: The theory accounting for the stress intensity and distribution in a beam subjected to transverse loading on the assumptions that the flexure is slight, that the elastic limit is not exceeded in any part of the beam,that all plane normal sections remain plane after bending, and that the intensity of either tensile or compressive stress in any normal section acting parallel to the axis of the beam varies directly as the distance from the neutral axis.

Compass: An instrument used to indicate the magnetic meridian or the direction of an object with reference to that meridian. An instrument for drawing circles.

Compass Brick: A brick having one edge shorter than the other. Used in lining shafts, etc.

Compensator: An equalizing device on machines or engines.

Component: A constituent part. One of the parts into which forces or stresses may be resolved or divided.

Compound Curve: A continuous curve composed of two or more arcs having different radii.

Compound Girder: Same as a "Built Girder." -- A girder made up of structural plates and angles.

Compound Locomotive: A freight locomotive having two or more cylinders (sometimes four) on each side, in which the steam is worked expansively from cylinder to cylinder.

Compound Pulley: Properly speaking, this term refers to a system of pulley-blocks and ropes usually called "Tackle."

Compound Stress: Same as "Combined Stress."

Compound Web Plate: A web composed of several thicknesses of plates.

Compression: The state of being compressed; shortening by pressure.

Compression Joint: A joint where compression members meet. A splice in a compression member.

Compressive Strain: The deformation caused by a compression load. Also called "Shortening."

Compressive Strength: The capacity to resist compression.

Compressive Stress: A stress which resists the shortening effect of an external compressive force.

Compressor: An apparatus for compressing liquids or gases.

Computations: Calculations; the figuring of bridgework.

[Computer]: In the context of the times this term referred to a person carrying out computations.

Concave Brick: A brick of special form with curved sides and radial ends used in making arches.

Concave Curvature: The direction of curvature as seen from a point on the chord joining the extremities of the arc. Opposed to Convex Curvature.

Concentrated Load: A load that is concentrated at a point or distributed over a very small area.

Concentrated Load Stress: Stress induced in a member by concentrated loads on a structure.

Concentration: A system of loading in which several loads are collected and applied at a point or over a very small area.

Conchoidal Fracture: A fracture showing shell-shaped depressions.

Concrete: An artificial stone made by mixing some cementing material with an aggregate composed of hard, inert particles of varying size. Usually the cementing material is Portland cement, and the hard, inert particles are sand and broken stone, water being added to make the cement active.

Concrete Batch Mixer: A type of mixer in which the materials are placed in the desired proportions for a definite amount of concrete and then mixed and discharged before a fresh supply of materials is entered.

Concrete Continuous Mixer: A type of mixer in which the materials are loaded into their respective hoppers and then mechanically discharged in small quantities at frequent and regular intervals into a common receptacle for mixing, from which the content is continually being forced into the discharging spout.

Concrete Floor: A floor made of concrete.

Concrete Girder: A girder built of concrete and usually reinforced with steel.

Concrete Masonry: Masonry composed of concrete."

Concrete Mixer: See "Concrete Batch Mixer." and "Concrete Continuous Mixer."

Concrete Pier: A pier made of concrete.

Concrete Pile: A pile made of concrete.

Concreting: The act of mixing and placing concrete.

Concurrent Forces: Forces in which the lines of action intersect in a common point.

Condenser: An apparatus for reducing gases or vapors to a liquid or solid form.

Conduit: An underground, narrow passage. A medium or means for conveying. A pipe, tube, or underground passage carrying electric wires, etc.

Cone Clutch: A clutch consisting of conical plug, sliding on its shaft and engaging a hollow drum shaped to receive the plug that rotates with the said shaft.

Cone Pulley: Same as "Stepped Pulley."

Conical Gear: Same as "Bevel Gear."

Conical Pulley: A pulley having a conical face.

Conical Roller: A cone-shaped roller placed under an object in order to provide for its rotating motion. Used under rim-bearing swing spans.

Conical Wheel: A wheel having a face conforming to the surface of a cone.

Conjugate Stresses: Two sets of stresses each of which acts parallel to the plane upon which the other acts.

Connecting Angle: An angle-iron used for connecting two pieces.

Connecting Bar: A bar which joins two parts or two members.

Connecting Chord-heads: Chord-heads used to connect bottom chord or web-channels to pins.

Connecting Plate: A plate used to connect two or more members of a truss.

Connecting Rod: A steel rod connecting the cross-head and the crankpin in an engine.

Conservation of Energy: The doctrine that the sum total of the energy of the universe neither diminishes nor increases, though it may assume different forms successively.

Consolidation Locomotive: A freight locomotive having two pilot, eight driving, and no trailer wheels.

Construction Bolt: A common steel bolt used temporarily during construction; such as a bolt to hold forms together.

Continuous Beam: A beam that rests on three or more supports.

Continuous Girder: A girder with more than two supports.

Continuous Span: A span that is supported on more than two piers or on more than one abutment and one pier and which distributes the load to the various supports on which it rests, or a series of consecutive spans effectively connected together over the points of support.

Continuous Stringer: A stringer that extends over two or more panels.

Continuous Truss: A truss which extends over three or more supports.

Contour Line: A line joining points having or representing equal elevations.

Contour Map: Same as "Topographic Map."

Contract: An agreement between two or more parties for doing or not doing some definite thing.

Contraction: The act of drawing together or shrinking. Diminishing the length, area, or volume of anything.

Contractor: One who contracts or covenants either with the government or other public bodies, or with private parties to furnish supplies, or to construct works, or to perform any work or service at a certain price or rate.

Contraflexure: A reversal of bending in a column or beam.

Converted Steel: Steel that has undergone a process of cementation in fire brick chambers or converting pots..

Converter: Same as "Bessemer Furnace."

Convex Curvature: The direction of curvature as seen from a point on a tangent to the curve. Opposed to Concave Curvature.

Conveyor: An apparatus or machine which carries material from one point to another.

Coordinate Paper: Paper ruled into small squares with every tenth line accentuated, for convenience in counting or in tracing a line.

Coordinates: A system of lines or angles, or both, by means of which the position of a point is determined by referring to certain fixed lines or points.

Cope: To dress. To put a coping on a pier. To notch steel beams, channels, etc.

Cope Chisel: Same as "Cape Chisel."

Coping: The top or cover of a wall, column, or pier. Usually made so as to project beyond the face below.

Coping-machine: A machine for notching structural shapes.

Copper: A reddish ductile metal having a specific gravity of 8.8 and a high conductivity for heat and electricity.

Corbel: A small shelf cantilevered out from a beam, wall, or column in order to support a beam or a superincumbent load. Sometimes called a tassel or bragger.

Corbel Bolsters: Bolsters made in the form of corbels. Projecting bolsters.

Corbel Course: A course of brick or stone projecting from the face of a wall and forming a support for an eccentrically applied load.

Core: To make or to cast a core. The inner part or filling of a wall. The internal mould in a casting.

Core Boring: A boring made by a core-drill by means of which samples of the material passed through, in the shape of a cylinder or core, are brought to the surface for inspection.

Core Drill: A rock drill having a hollow cutter so that as it revolves a core is cut out which extends upward into the interior of the drill bit and shaft. At suitable intervals the core is broken off and brought to the surface for examination.

Corner Bracket: A steel bracket rigidly attached in a re-entrant corner of a structure.

Cornice: The projection at the top of a wall that is finished by a blocking course.

Corrosion: The disintegration of a substance by the action of chemical agents.

Corrugated: Bent or drawn into parallel furrows or ridges. Wrinkled; fluted.

Corrugated Bar: A type of deformed bar used as reinforcement in concrete. The deformations consist of a series of ridges transverse to the axis of the bar, their function being to engage the salient portions of the aggregate.

Corrugated Dolly: A straight dolly with one cupped end, the other being an oval knob.

Corrugated Iron: Sheet iron formed with ridges by passing it between fluted rollers.

Corrugated Pile: A precast, tapered, concrete pile with semi-cylindrical flutes running lengthwise, having reinforcing rods, and a two-inch hole in the centre for a jet.

Corrugated Plate: A steel plate bent into a series of parallel furrows and ridges.

Corrugated Steel Floor: A floor system composed of corrugated steel.

Cost: The price paid or the expenditure involved in procuring or constructing anything.

Cotter: A beveled piece of wood or steel, used as a wedge for fastening. Also a split steel key, used for the same purpose.

Cotter Bolt: Same as "Cotter Pin."

Cotter Key: Same as "Cotter.

Cotter Pin: A split steel key or pin used to fasten large pins so that they cannot move endwise. Also used to denote the large pin holding the cotter.

Counter: An adjustable diagonal in a truss, not subjected to stress except for certain partial applications of the live load.

Counter Shear: A shear in opposition to another shear.

Counter Stress: A stress in the web member of a truss which occurs for certain positions of the live load and is the reverse of the usual stress in the member or panel.

Counter Strut: A web member subject to both compression and tension.

Counterbalance: To weigh against with an equal weight. Same as a counterpoise.Sometimes used as a synonym for counterweight.

Counterbore: The reboring of a cylindrical hole for a part of its length to a larger diameter than the original.

Counterbrace: A web diagonal which transmits a stress in the opposite direction (in relation to span-length) to that carried by the main diagonal of the same panel.

Counterfort: A short cross-wall built behind the main wall to give it additional stability by acting as an anchor to hold back the main wall. Its action is opposite to that of a buttress.

Counterpoise: Same as "Counterbalance."

Countersink: A drill or brace-bit for countersinking. To form by drilling or turning a conical cavity in timber, metal, or other material, for the reception of the head of a bolt, rivet, or screw, so that the end thereof may lie flush with the surface of the said material.

Countersink Drill: A tool combining a drill and a countersink in one piece.

Countersinking Reamer: A bit with a conical-shaped cutting head, used for countersinking holes.

Countersunk Bolt: A bolt having its head beveled and flattened, so that when put into place the said head will not project from the surface.

Countersunk Rivet: A rivet used in countersunk holes in which the point, while hot, is hammered down to fill the countersinking.

Counterweight: A weight that counterbalances some other weight. To weight against. Similar to "Counterbalance."

Couple: Two equal and parallel forces acting in opposite directions and in different lines.

Coupling: The act of uniting and joining. The part that unites and joins.

Coupling Box: The box or ring of metal connecting the contiguous ends of two lengths of shafting.

Coupling Link: A link connecting two objects.

Coupling Pin: A pin that couples links in machinery, chains, etc.

Coupling Valve: A coupling having one end threaded to receive a metal pipe and the other with a shank to fit a hose.

Course: A horizontal layer of stone in a masonry wall, or of a pavement.

Coursed Rubble: Rubble masonry laid in courses which may or may not vary in thickness.

Coursing Joint: A joint between two voussiors in masonry.

Cover Plate: A plate fastened on the flanges of a girder to give additional cross-section thereto; a top or bottom plate of a chord member.

Crab: A short shaft or axle, mounted in a frame, having squared ends to receive hand cranks, used to wind up a rope and thereby raise a load.

Cradle: A term applied to various kinds of timber supports, which partly enclose the mass sustained. To incline suspending cables to the vertical."

Cradling: The placing of the cables in a suspension bridge so that they are closer at the sag than at the supporting towers.

Cramp: A short bar of metal having its two ends bent downward at right angles for insertion into two adjoining pieces of stone, wood, etc., to hold them together.

Cramp Iron: Same as a "Cramp."

Cramp Joint: A joint between plates of metal in which the edges are thinned by hammering.

Crandall: A mason's tool consisting of an iron bar for the handle, having a slot near one end into which are keyed a number of double-headed mason's points. Also to dress stone with a crandall.

Crandalled Dressing: A finish in stonework in which the face of the stone is dressed to a plane with a crandall.

Crandalled Masonry: Any type of masonry in which the stones have been dressed with a crandall.

Crane: A hoisting machine mounted so that it can move in a horizontal direction and thereby place the load at any point within its range.

Crane Girder: A girder either stationary or movable, used for hoisting.

Crank: A device or mechanism for producing rotation about an axis. Its usual form is a bar or disk set at right angles to the shaft and containing a crank-pin, remote from the axis of rotation, to which the force is applied. An iron brace or support. A twist or a turn.

Crank Auger: An auger operated by turning a crank; used on metal or wood.

Crank Pin: A pin connecting the ends of a double crank or the projection from the end of a single crank.

Crank Shaft: A shaft having one or more cranks attached.

Creeper Traveler: A small movable derrick running on a track on the upper chord of a truss. It usually has two booms. A mule traveler.

Creosote: An oily product obtained from distilled coal-tar with the addition of caustic soda and sulphuric acid.

Creosoted Lath: A lath treated with creosote.

Creosoted Timber: Timber that has been thoroughly saturated with creosote oil or dead oil.

Crescent Truss: A truss with both chords curved upward, or both downward, and making sharp intersections with each other at the ends, producing in outline the appearance of a crescent, the web system being of the triangular type.

Crest: The top of an embankment. Also the highest water in a flood.

Crib: An inner lining of a shaft or well, consisting of a frame or box of timbers and a backing of planks, to keep the earth from caving in. To build up a support by placing heavy timbers in layers, the sticks of the consecutive layers generally running in directions at right angles to each other. That portion of the base of a pier lying between the top of the deck above the working chamber and the neat work of the shaft.

Cribbing: Timbers piled cross-wise in order to form a support for a load.

Crimp: To offset an angle by bending so that, it will fit over the flange of another angle, thus doing away with filler plates beneath.

Crimping-machine: A machine which crimps angles. Used in bridge shops.

Cripple: To disable or to weaken. Also to give or to give way.

Crippling Load: A load which, if put on a member or a structure, will disable or weaken it.

Crippling Stress: The stress resulting in a member at the point of crippling. The stress necessary to cripple the member.

Critical-speed: That speed of a train on a bridge which produces the maximum impact.

Cross Beam: A beam which runs transversely to the centre line of a structure.

Cross Bond: A masonry bond in which a course composed of stretchers, except at the ends where headers are used, is covered by a course in which headers alternate with stretchers.

Cross Bracing: Same as "X Bracing."

Cross-cut Saw: A saw adapted by the filing and setting of its teeth to cut across the grain of the wood.

Cross-fibred Wood: A wood in which the fibres run obliquely to the axis of the tree, reversing direction in different layers and thereby producing a crossed effect.

Cross Frame: A transverse bracing frame between stringers. Also termed a "Buck Brace."

Cross Girder: Any girder passing across a bridge from one truss or main girder to another, and, generally, perpendicular to the truss or girder planes.

Cross-grained: Of irregular or gnarled condition. Applies to timber.

Cross-grained Wood: Same as "Cross-fibred Wood."

Cross-hairs: Two very fine hairs or strands of spider's web stretched at right angles to each other across the focal plane in a transit or level.

Cross Hatch: See "Crosshatching."

Cross-head: A machine element having the shape of a "T" or a cross, and running on guides in order to control and steady the motion of another member. Often used on piston rods.

Cross-head Pin: A pin that fits in a cross-head and furnishes an attachment for the connecting rod.

Cross-over: A connection between two parallel tracks.

Cross Riveting: Same as "Staggered Riveting."

Cross-section: A section made by a secant plane perpendicular to the axis of the member, structure, or any construction.

Cross-section Book: A surveyor's field book ruled specially for plotting cross-sections.

Cross-section Paper: A standard quadrille-ruled paper in which the principal squares are one inch on a side and the secondary squares are one-tenth of an inch on the side.

Cross-section Rod: A rod for measuring horizontal distances. Graduated in feet and tenths, with the figures so placed as to be read easily when rod is horizontal. It is provided with a level bulb so that it can be leveled.

Cross Tie: A railroad tie or sleeper.

Cross-wires: Two very fine wires set at right angles to each other across the focal plane of a level or transit. Similar to "Cross-hairs."

Crosshatching: The method of shadowing or hatching by using two intersecting sets of parallel lines.

Crossing: An intersection. The place where two roads or railroads cross. The place where a river or stream may be crossed. The term is often used for the bridge crossing the stream or river.

Crow Bar: A hand bar of steel with a slightly-bent, wedge-shaped end, which is sometimes forked. Used as a pry or lever.

Crow-foot Seam: A vein in rock containing dark-colored, uncemented material.

Crown: The top or summit of the curved cross section of a roadway pavement; the centre being made higher than the sides to facilitate draining the roadway. The top of an arch ring.

Crown Thrust of an Arch: The thrust or compression existing at the crown of an arch due to the loading.

Crown Tile: A roofing tile used at the hips or ridges of roofs.

Crown Valve: A crown-shaped valve sliding over a slotted box, such as the slide valve in a steam engine.

Crown Wheel: A wheel with teeth set perpendicular to the plane of rotation.

Crowning Pulley: A pulley in which the face has a slight convexity in order to held the belt on better.

Crucible Cast Steel, or Crucible Steel: Steel made by melting down in a closed crucible the various grades of iron or steel with or without the addition of carbon, ore, or other materials.

Crucible Steel: Same as "Crucible Cast Steel."

Crusher: A machine that crushes or applies a load sufficient to overcome the compressive resistance of any substance; for example, a "rock-crusher."

Crushing: The breaking down of a material due to the application of a load.

Crushing Strain: An incorrect but rather common expression for the ultimate strength in compression. See also "Ultimate Strength."

Crushing Strength: The ultimate power of a material to resist disintegration by crushing.

Crystalline: Consisting of crystals. Relating or pertaining to, crystals. Having a definite structure referable to one of the crystallographic systems.

Crystalline Fracture: A fracture leaving small crystals showing.

Crystalline Iron: An iron which when broken shows a crystalline fracture.

Cubature: The cubic measure or contents of anything.

Cubic Curve: A curve of the third degree.

Cull: To sort out or select material that does not meet the requirements of the specifications. Any piece that has been culled.

Culvert: A small covered passage for water under a roadway or embankment.

Cumulative Stress: A stress that piles up in a member.

Cumulative Vibration: A piling up or a superposing of vibration. An increasing vibration.

Cup-and-ball Joint: Same as "Ball-and-socket Joint."

Cup Dolly: Any dolly that has a cupped end for receiving rivet heads.

Cup Fracture: A fracture in the shape of a cup.

Cup Washer: A washer having a cup for receiving the nut of a bolt.

Curb: A broad, flat, circular ring of wood, iron, or stone placed under the bottom of a circular wall, as in a shaft or well, to prevent unequal settlement. The outer casing of a turbine wheel. The edge of a sidewalk next to the main roadway. The wheel-guard in a bridge. To strengthen or protect by means of a curb.

Curb Chain: Any chain used as a check upon the motion of any moving piece or apparatus.

Curb Girder: A steel or reinforced concrete girder holding up the sidewalk and forming the curb of a roadway.

Curled Wood: A wood in which the fibres are fine and run in folds or ridges, producing a curly effect in some places.

Current: The flow of a liquid or gas, or the movement of electricity.

Current Meter: An apparatus for measuring the velocities of flow in streams.

Curtain Wall: A thin wall. A partition wall that carries no superimposed load.

Curvature: The amount of curving or bending of a line, figure, or body. It is measured by the ratio of the deflection angle between end tangents (measured in radians) to the length of the intervening arc.

Curve: A line continuously bent so that no portion of it is straight. A continuous bending; a flexure without angles. A drafting instrument for drawing curved lines.

Curved Girder: Any girder in the shape of a curve.

Curved Line: A line which changes direction at every point.

Curved Top Chord: A top chord that approximates to the form of a curve. Strictly speaking such a chord is "polygonal," as curving chords between panel points is not permissible.

Cushing Pile: A square timber pile driven in a group in which all the piles are practically in contact. This method of pile foundation is now obsolete.

Cushion: A confined body of air or steam which serves under pressure as a buffer to absorb impact.

Cushion-coat: A layer of material used in pavements, from one-half to one inch thick, placed between the wearing surface and the foundation.

Cusp: A point in a curve where two branches have a common tangent. The intersection of two curves.

Cuspidal Curve: A curve ending in or shaped like a cusp.

Cut Gears: Gears in which the teeth are cut by a machine so as to mesh accurately, in contra-distinction to cast gears in which the teeth are left in the rough.

Cut Nail: A nail which is cut from a plate.

Cut-off: A device for cutting off the passage of steam from the steam chest to the cylinder of an engine. A channel cut through a narrow neck of land to straighten a river. That point where piles or timbers are sawed off after being put in place.

Cut-off End: That part of a pile that has been sawed off or wasted after the pile is in place.

Cut Spike: A spike cut or stamped out of a sheet of metal.

Cut Stone: Stone which has been dressed with a mason's chisel to a smooth surface.

Cut-stone Masonry: Any type of masonry composed of cut stone blocks having smoothly dressed beds and joints.

Cutter: A steel tool for cutting metals. Also the cutting edge on a cutting machine.

Cutting Edge: The edge of the tool which does the cutting. The edge of timber or steel angles placed on the bottom of the working chamber of a caisson.

Cutting Tool: A tool used for cutting materials.

Cutwater: A starling; the projecting ends of a bridge pier, etc. Usually so shaped as to allow water, ice, drift, etc. to strike without injury to the structure.

Cycle: A complete revolution. Any recurring period in which a series of events or phenomena takes place. A series that repeats itself. A series of operations by which any product is finally restored to a primary condition.

Cycloid: A curve generated by a point on the circumference of a circle when the circle is rolled along a straight line and kept always in the same plane.

Cycloidal Curve: Same as "Cycloid."

Cyclopean Concrete: Concrete in which large stones or boulders, sometimes called plums, have been bedded.

Cylinder: A solid of revolution generated by a rectangle rotating about one of its sides. A machine element having a circular bore.

Cylinder Pier: A pier made of a cylindrical steel shell filled with concrete.