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Glossary of Bridge Terminology



S-Wrench: A wrench having a bent handle like the letter S.

Sack: A bag. To discharge an employee.

Saddle: A block having its top hollowed for carrying a rounded member. A block at the top of the tower of a suspension bridge over which pass the suspension cables or chains.

Saddle Head: A hollow casting resting on the heads of columns to sustain another column above and to allow beams to pass through.

Saddle Joint: A sheet metal joint in which one edge overlaps and straddles the upturned edge of the next.

Safe Load: Any load which does not produce stresses, in the members, having higher intensities than those allowed in the specifications.

Safety-factor: The ratio of ultimate load to the greatest allowable working load. This term is losing favor with engineers, as its use has been abused. There is no such thing as a factor of safety for a well proportioned bridge, for each member should have an intensity of working stress proportional to the character and amount of work which it has to perform. This is best accomplished by adding to the live load stress a certain varying proportion thereof to allow for the effect of impact.

Safety Rail: A guard rail.

Safety-stop: An automatic device on a hoisting apparatus designed to prevent the machine from falling in case the ropes or the machinery should break.

Sag: The greatest deviation from a straight line joining its ends which a flexible body undergoes, such as a rope or a chain.

Sal-ammoniac: Commerical ammonium chloride.

Salient: A portion projecting beyond the general line of the structure.

Salt: Chloride of sodium (NaCl). Used in mixing concrete in freezing weather to lower the freezing point of the mixture. A compound of basic and acid substances.

Salvage: That portion of a structure or plant that can be saved from destruction after having been used.

Salvage-value: The price for which a structure or a plant is sold second-hand.

Sampling-iron: An iron bit or spoon for making a hole in a barrel and pulling out a sample of the contents. Used by cement testers.

Sand: Broken down, water worn, crystalline rocks of a size less than one-tenth of an inch in diameter.

Sand-bag: A bag filled with sand, used to close a gap through which water is flowing.

Sand Bar: A deposit of sand in a river.

Sand Bearing: A bearing of confined sand used for the purpose of lowering the object that is temporarily supported. The lowering is effected by permitting the sand to escape. Also the support for the core in a sand mould for casting.

Sand-blast: A device for projecting sand particles, at a high velocity, through a nozzle by means of compressed air. Used in cleaning metal.

Sand Briquette: A briquette made of sand and cement mortar.

Sand Cement: A mechanical mixture of Portland cement and sand ground together so as to produce a very fine powder. Its only raison d'etre is cheapness, as it is not as strong as good Portland cement.

Sand-hog: A term applied to any laborer working under compressed air in the sinking of piers.

Sand-hog House: A house near the bridge site, used by sand-hogs between shifts.

Sand Hoist: An apparatus for lifting sand.

Sand Lift: Same as "Sand Hoist."

Sand Pile: A pile made by forming a hole in the ground and filling the same with sand thoroughly tamped.

Sand Pump: A pump for raising sand, such as the Eads' pump.

Sand Screen: A sieve for sifting sand.

Sand Sieve: A sieve with meshes less than a tenth of an inch in size, used for sifting sand.

Sand Trap: A device for separating sand from water.

Sandstone: A rock formed by the consolidation of sand.

Sandwich Girder: A girder or beam having an iron or steel plate inserted between two wooden beams and rigidly bolted thereto.

Sap: The fluid which circulates in plants, trees and other vegetation. Also applied to moisture in newly quarried rock. Same as "Quarry Sap."

Sap Tie: A tie which shows more than the prescribed amount of sapwood in cross-section.

Sap Wood: The outer and lighter colored portion of a timber containing sap.

Sappy: A condition of steel as indicated by the surface of fracture where the grains are very coarse and bright.

Sash Brace: A horizontal member secured to the posts or piles of a bent between the cap and sill.

Saucer Block: A cast iron or steel block dished, or saucer shaped, in which a capstan or the bottom of a boom rests and turns around.

Saw: A cutting tool consisting of a thin blade or sheet of steel having teeth on one or both edges and handles or other attachments for giving it motion.

Scab: A. plank used in making a splice between two timbers.

Scab Plate: Same as "Scab."

Scabbed: The condition of being joined by a scab or scabs.

Scabbing Hammer or Scaling Hammer: A hammer used for loosening and removing scale from steam boilers.

Scabbled Dressing: A form of stone dressing for rubble masonry in which the angular projections of the stones have been dressed off with a stone-axe, or hammer.

Scaffold: A temporary platform or staging for supporting workmen during the building of a structure.

Scaffolding: A general term covering all the scaffolds on a job.

Scale: A graduated stick of wood or metal for measuring or laying off distances. To measure with a scale. The ratio of the linear dimensions of a drawing to the corresponding dimensions of the actual object so represented. A coating of oxide which forms on the surface of heated metal.

Scaling Hammer: Same as "Scabbing Hammer."

Scarf Joint: A joint between two pieces made by scarfing or beveling their ends so that when the parts are placed together they form one continuous member.

Scarf Weld: A weld in which the ends of the pieces are made to lap over each other and then joined by welding.

Scarp: A steep slope.

Schedule-prices: The prices stipulated in a contract for the performance of labor or the furnishing of materials at unit rates. Called also "Unit Prices."

Schwedler Truss: A modification of the Whipple Truss. See Fig. 22aa.

Fig. 22aa

Scoop: A special type of bucket having a cutting edge on the front side, used in dredging. A spade having the sides turned up.

Scoop Dredge: A dredge provided with one or more scoops

Scooping: The act of dredging with a scoop.

Scotch: To chip; to hack. To block, or prop up.

Scour: A clearing out or removal of silt and sand in the bed of a stream by a strong current. To remove such material in that manner.

Scow: A flat-bottom boat.

Scrag: To straighten a spring, etc., which has been bent, by pushing, in the bulge and releasing.

Scrap: Discarded material. Junk.

Scrap Iron: Old iron no longer suitable for its original purpose. Waste iron, junk iron.

Scrap Pile: A heap or a pile of junk.

Scraper: A tool for scraping up loosened earth and hauling it away; drawn by horses or mules and guided by handles attached to its rear.

Scratch Awl: Same as "Scribing Awl."

Screeds, or Screed-iron: Strips of wood used for gauges for the finish of plastering. An angle iron on legs, or other device, which, in concrete work, is set on the slab form to serve as a guide in forming the top of the slab.

Screen: A large sieve; device for sifting and separating particles of different sizes.

Screening: The act of sifting and separating particles by a screen. Also applied to the material passing through the screen--generally used in the plural.

Screw: A cylindrical bar on which has been formed a helical projection or thread.

Screw-adjustment: An adjustment in which motion is provided by a screw.

Screw Bolt: A bolt having a square head for turning with a wrench and a wood screw on the opposite end for entering wood. A form of lag screw.

Screw Clamp: A clamping device operated by a screw.

Screw Disc: A plate or casting circular in plan, shaped like the thread of a screw, or having a helicoidal surface.

Screw Dolly: A straight dolly with a shaft that screws into the head. Used between beams for bucking up.

Screw-end: The threaded end of a bolt.

Screw Jack: A large screw working in a nut set in a strong frame or forming a part thereof, which in turn serves as a base to carry the load.

Screw Joint: A joint in which one piece screws into another or in which both screw into a common sleeve or coupling like the ordinary pipe joint.

Screw Pile: A steel pile similar to a disk pile but having a portion of a helicoid at its point so as to enable the pile to be screwed into place.

Screw Stock: Same as "Die Stock." -- The frame, with handles attached, used for holding and turning the dies which cut the threads on rods or pipes.

Screw Thread: The thread on a screw, having a cross-section like an inverted V.

Screw Track-spike: A large, threaded, square-headed bolt with the head spread out on the underside. These screw spikes are used in place of the ordinary track spike, especially on bridges. A hole is first bored in the tie at the right point and then the spike is screwed into place.

Scribe: To trim off the edge of a board, etc., so as to make it fit closely at all points to a certain line; to mark with a scriber.

Scriber: A sharp-pointed tool for marking metal.

Scribing Awl: A straight, sharp-pointed awl used for making lines on wood and metal; sometimes called a scratch-awl.

Scrids: Same as "Screeds."

Scurf: To flake off, or the material which flakes off. Dross.

Seam: A crack in a badly rolled steel section. A crack or parting in rock.

Seat Angle: A short angle riveted to a column to support temporarily a beam during erection.

Secant: Any line cutting another line. A trigonometric function defined by the ratio of the hypothenuse of a right-angled triangle to its base, in reference to the acute angle adjacent to the said base.

Second-class Masonry: A term applied to broken range rubble of superior quality laid with horizontal beds and vertical joints on the face, with no stone less than eight inches thick, well bonded, and leveled as well as can be done without hammer dressing.

Second Set: The hardening of mortar that has once partially hardened and which has been disturbed before getting its final set.

Secondary Member: A subordinate part of a bridge, as a lateral. Generally refers to the suspenders and sub-diagonals of trusses.

Secondary Stress: An indirect stress set up by the deformation of a member caused by primary stresses.

Secondary Strut: A secondary member taking up compression.

Secondary Truss: A truss supported by another truss.

Secondary Truss-Member: A subsidiary member used to support a main member, or to transfer a load from a mid-panel point to a panel point or panel points.

Section: The trace on a secant plane made by the object cut. Sometimes improperly used for a member or segment thereof.

Section-modulus: The moment of inertia of the area of a section of a member divided by the distance from the centre of gravity to the outmost fiber.

Section Required: The section area of a member required properly to resist the total force acting on the said member.

Sectional Area: The area enclosed by the periphery of a section of a piece or member.

Sector: That portion of a circle included between two radii and the subtending arc.

Sediment: The fine material which settles to the bottom of water or other liquid.

Seepage: The oozing or percolation of water through a material. Water which has thus percolated.

Segment: That portion of a circle lying between an arc and its chord. A portion of a member.

Segmental: Pertaining to a segment.

Segmental Arch: A circular arch in which the intrados is less than a semi-circle.

Segmental Roller: A roller composed of two opposing circular segments and an intermediate connecting web; used under bridge-shoes.

Seize: To bind a journal in its bearings by overheating. To fasten or bind by turns or windings of cord, line, or small rope.

Self-hardening Steel: Same as "Mushet Steel." -- A steel containing one and one-half per cent of carbon and from five to eight per cent of tungsten, which when hardened by air cooling holds its temper until it becomes red-hot. A steel produced by the Mushet process of recarburization, which consists of adding spiegel or other form of manganese.

Semaphore: An apparatus for making signals with movable arms.

Semi-cantilevering: A method of erecting a span without falsework, by cantilevering from an adjacent span, or adjacent spans, or from a rock bluff by toggles, and afterward removing these so as to leave the structure as a simple span.

Semi-circular: Pertaining to the half of a circle.

Semi-intrados: That portion of the inner arch curve between the crown of an arch and its springing line.

Semi-polar Coordinates: A system of coordinates in which the radius vector of the polar system is combined with one of the coordinates of the rectangular system.

Separators: Small, cast-iron, wheel-like blocks, used to separate stringers in trestles, or the timbers that form the chord sections of a Howe truss bridge.

Set: A condition of hardening exhibited by cement after mixing with water. The permanent change or deformation which a material subjected to stress undergoes when its elastic limit is exceeded. An outfit of tools. A tool for shaping rivet heads.

Set Pin: Same as "Dowel." -- A straight pin of wood or metal driven part way into each of the two faces which it unites.

Set Screw: A type of screw similar to a cap screw but without a shoulder under the head and with a cup-shaped end for a better grip on the object.

Sewer Brick: Ordinary hard brick, smooth and regular in form, suitable for sewer construction.

Shackle: A U-shaped attachment for large pulley-blocks replacing the customary hook.

Shackle Bar: A bar used for pulling driftwood from a stream.

Shackle Joint: A joint formed by a clevis or a shackle with a bolt.

Shade: A painter's term descriptive of that difference between colors which results from a variation in luminosity only, the other color constants being essentially equal.

Shaft: A well-like opening, nearly or quite vertical, in cribs and caissons; used for hoisting material through or for the passage of workmen. A long, cylindrical bar capable of rotating and transmitting torque.

Shaft Bearing: A support for a revolving shaft.

Shaft Coupling: Any of the several devices for joining the ends of two shafts.

Shafting: A general term for a number of shafts connected up to form a system. Rounds used for making shafts.

Shafting Box: A one-piece type of bearing for shafting, having a base and bolt holes for bolting to a support.

Shaker Bar: Same as "Pick-up Bar." -- A hand bar with two prongs riveted on one end; used, after the concrete is poured, for picking up and shaking the reinforcing steel lying on the bottom of the form.

Shakes: Splits or checks in timber which usually cause a separation of the wood between the annular rings.

Shale: A, hard, clay-like formation having a fissile structure often shading off into slate.

Shank: That part of a tool connecting the handle with the working part.

Shank Mortar-mixer Hoe: A solid shaft hoe with two circular openings in the blade.

Shank Street Hoe: A hoe having a solid shank with a solid blade. The common hoe.

Shape: Any rolled beam or bar used in a structure.

Shape Steel: Same as "Shape."

Shaper: A machine tool for planing or finishing metal.

Sharp Sand: A sand having sharp-edged grains or particles.

Shay Locomotive: A geared Mallet locomotive.

Shear: To slide one part of a body upon an adjacent part. The stress set up in opposition to a shearing action.

Shear Diagram: A diagram showing the variation of the shear along a beam or truss.

Shear Steel: Steel made in the form of bars from blister steel by shearing the latter into short lengths, piling these upon each other and heating, and welding them by rolling or hammering into one piece.

Sheared Edge: An edge of a plate which has been cut in a shearing machine.

Sheared Plate: A plate sheared from another larger plate. Any plate the edges of which are sheared.

Shearing Machine: A machine for. shearing metal, consisting of a movable jaw-cutter operating against a fixed cutting edge.

Shearing Modulus of Elasticity: The ratio of the, unit shearing stress to the accompanying angular deformation. It generally equals two-fifths of the lineal modulus. See "Modulus of Elasticity."

Shearing Strain: The deformation produced by a shearing force.

Shearing Strength: The resistance which a body can offer to a shearing force.

Shearing Stress: A stress which resists any action tending to slide one part of a body past an adjacent part.

Shears: Same as "Shearing Machine."

Sheathing: A covering or casing of planks. Used on caissons, cribs, and the like.

Sheave: A wheel with a grooved face for carrying a rope or cable.

Sheave-stand: A frame or support for a sheave and its bearings.

Sheet Iron: iron which has been rolled thin into sheets.

Sheet Lead: A thin plate of lead made by passing a flat ingot repeatedly through rollers.

Sheet Packing: Any packing put up in the form of thin layers.

Sheet Pile: A form of piling used to shut out water, generally made of several planks spiked or bolted together, and arranged to secure a tongued and grooved effect when driven close together. Steel shapes are also employed for this purpose.

Sheet Piling: A general term for a number of sheet piles taken collectively. See "Pile "

Sheeting: Same as "Sheathing."

Shelf: A flat projection from a wall or column.

Shelf Angle: Same as "Seat Angle."

Shell: A hollow cylinder for piers. A casing. A framework not filled in.

Shellac: A gum made from a resinous exudation of an East Indian scale insect. When mixed with alcohol it forms a varnish which is much used in the arts and is termed "Shellac."

Shield: A bulkhead or contrivance to protect workmen and property, used in certain classes of underground work.

Shift: A relay or change of workmen.

Shift-boss: The foreman of a shift.

Shim: A small piece of wood or metal placed between two parts or members of a structure to bring them to a desired relative position.

Shim-bolt: A bolt used to fasten a shim in place.

Shimming Plate: A plate used as a shim for increasing the elevation of a bearing.

Shingle: A thin, wedge-shaped piece of wood used for roof covering, laid overlapping each other. A steel plate employed in making a splice. To make a compound splice by cutting the component parts at different places.

Shingle Splice: In a member composed of a number of component parts, such as one with compound web plates, a shingle splice consists in cutting all of the said component parts at different but near-by locations and letting the splice plates extend over all the individual joints.

Ship Auger: An auger with a long shank in which two cranks are formed.

Shipping: A general term applied to vessels collectively. The act of despatching goods.

Shipping-bill: A list of the articles shipped.

Shipping Invoice: An invoice of goods shipped.

Shipping-list: A list of all the articles to be shipped.

Shipping-weight: The weight of the articles shipped, including that of the wrappings and packing.

Shock: A jar; the effect of a blow; the sudden absorption of energy.

Shoe: That part or detail of a span which transfers the load from the end pin to the bearing plate or to the intervening rollers. Also a cast-iron point used on piles when driving them through hard ground.

Shoe Block: A form of pulley block. Also same as "Base Casting" (A steel or iron casting upon which the bridge-shoe rests.)

Shoe Pin: The pin in a shoe which receives the load from a span or a column.

Shoe Plate: The bottom plate of a shoe resting on the masonry.

Shoot: Same as "Chute."

Shop: The place where bridge spans are fabricated.

Shop Drawing: A drawing of a structure or machine showing all parts and dimensions so that the shop can actually build what is indicated on the drawing without other information.

Shop Rivets: A rivet driven in the shop.

Shore: The land adjacent to a body of water. A support or a prop. To support with a shore.

Shore Span: Either the first or the last span of a bridge.

Shoring: A general term covering a system of shores or props.

Short Column: A column which will fail by crushing.

Short-leaf Yellow Pine: A variety of pine tree resembling the loblolly pine and having a wood approaching that of the Norway pine. Its needle leaf is shorter than that of the loblolly or Norway pine.

Short Ton: A ton of two thousand pounds.

Shot: Small lead balls, used fer gradually applying a load in a certain style of testing machines. An explosion in blasting.

Shoulder: The bearing surface perpendicular to a member produced by. a projection on or a recess in such member.

Shoulder Block: A sheave in a frame having a shoulder to prevent the rope through the block from becoming jammed.

Shove Joint: A joint in brick-work obtained by shoving the brick on its mortar-bed so as to pile up mortar at its end and thereby fill the vertical joint.

Shrink: To draw together; to contract. To attach one piece to another by heating it, placing it, and then allowing it to cool.

Shrink Rule: A rule having slightly exaggerated divisions (an excess of one-eighth of an inch in twelve inches) to compensate for the shrinkage of metal in cooling. Used by pattern makers.

Shrouded Pinion: A pinion in which the sides of the rim extend up on the ends of the teeth, thereby bracing them and giving them extra strength.

Shut: A seam or opening in metal formed during manufacture.

Side Bracing: The bracing on the sides of falsework, of a timber trestle, or of a pony-truss bridge.

Side Track: A secondary track parallel to and connected with the main track of a railroad.

Sidewalk: A walk for pedestrians at the side of the roadway of a bridge.

Siding: Same as "Side Track."

Siemen's-Martin Process: The acid open-hearth process of making steel.

Siemen's Process: A process for making steel by using a regenerative gas furnace which utilizes the heat of the escaping gases in reheating firebricks placed in the passageways for air and gas leading to the furnace. Two sets of passageways are required, being used alternately. While one is conveying the gas and air to the metal, the other is being reheated by the escaping gas from the hearth. Every twenty or thirty minutes a valve is moved, so as to alternate the flow.

Sieve: An apparatus consisting of wires strung on a frame or box, so as to form a network of meshes through which a granular material is sifted.

Silica: A dioxide of silicon (Si02). It occurs in nature as quartz.

Silica Cement: Same as "Sand Cement."

Silicate of Lime: A union of silica and lime (Si02CaO).

Silicious: Having the nature of silica or pertaining thereto.

Silicon: A chemical element of the non-metallic order.

Silky Fracture: A fracture showing a glossy surface.

Sill: The lower horizontal member of a framed bent.

Silt: A fine, earthy sediment deposited by muddy water.

Simple Beam: A beam having its ends free and resting on two supports only.

Simple Curve: In railroad work a circular arc extending from one tangent to the next; a curve of constant radius.

Simple Span: A span that rests on two supports, one at each end, and that does not affect the stresses in the adjoining spans.

Simplex Pile: A type of filling pile made by driving a steel shell, having a steel point, into the ground and filling same with concrete while the shell is being withdrawn.

Sine Curve: A curve in which the abscissa is proportional to the angle, and the ordinate is proportional to the sine of the angle.

Single-acting Piston: A piston which is subjected to periodic pressure on one side only.

Single Block: A pulley block containing one sheave only.

Single Cancellation: The arrangement of the web members of a truss having only one complete system of diagonals.

Single Concentration: Similar to "Double Concentration" except that the second excess load is omitted. It, too, is no longer used.

Single Intersection Truss: A truss with one web system only. See Fig. 22g.

Fig. 22g

Single Intersection: Same as "Single Cancellation."

Single Lacing: Same as "Lacing." -- A system of bars not intersecting each other at the middle, used to connect two leaves of a strut in order to make them act as one member.

Single Latticing: Erroneously used for "Single Lacing."

Single Lip Screw Auger: An auger which has a bit with only one lip or cutting edge.

Single Locomotive Excess-load: A live load in which a single concentration is followed by a uniform car load.

Single Punch: A punching machine that makes one hole at a time.

Single Riveting: A term applied to lap-joints in which one row of rivets only is used to fasten the plates.

Single Shear: A sliding, or a tendency to slide, on one plane.

Single Shear Steel: Same as "Shear Steel."

Single Track: A track with a single pair of rails.

Sinking: The process of lowering cribs, caissons, and piers to their foundations.

Sinking Fund: A fund built up during a period of time to provide a given sum of money at the end of that period, by making at regular intervals uniform deposits which draw compound interest.

Siphon: A bent tube or pipe having unequal legs, employed for drawing off water when the summit of the bend is higher than the supply, and the discharge end (the longer leg) is lower than the supply.

Siphon Condenser: Same as "Injection Condenser." -- A form of condenser in which the injected water comes in contact with the steam.

Siphon Culvert: Same as "Siphon."

Sisal Hemp: Same as "Henequin Hemp." -- A kind of hemp which grows in Cuba and parts of Mexico.

Sisal Rope: Rope made from sisal hemp.

Sister Block: A block having two sheaves, arranged in tandem.

Sister Hook: A pair of hooks on the same axis facing each other and fitting closely together when in use.

Skeleton-construction: A framework of structural steel which sustains all the external loads or forces from the top of a building to the foundation.

Skeleton Diagram: A diagram which shows the general peripheral outline and the main members in a truss.

Skeleton Drawing: Same as "Skeleton Diagram."

Skelp: A strip of iron or steel prepared for making pipes and tubes.

Skew: Making an oblique angle.

Skew Arch: Same as "Oblique Arch." -- An arch in which the axis is not perpendicular to the central plane of the structure.

Skew Bridge: A bridge in which the horizontal lines joining corresponding end pins of the opposite trusses are oblique to the planes of the said trusses.

Skew Crossing: Same as "Oblique Crossing." -- A crossing in which the intersecting centre lines make an oblique angle with each other.

Skew Portal: A portal on a skew span.

Skew Span: A span making an angle, other than a right angle, with the axes of the piers and abutments.

Skewback: The beveled stone, iron plate, or course of masonry which supports the foot of an arch ring. Also the casting on the end of a trussed girder to which the tension rod is attached.

Skid: To slip or slide without revolving.

Skid Girder: A built-up plate-girder with the web lying in the horizontal plane riveted to the inside of the web members of a truss to protect these members in case of derailment of trains.

Skid-way: A frame or form used for skidding heavy articles.

Skids: Timbers used as a track in sliding heavy objects.

Skim-coat: A finishing coat of plaster used to give a smooth surface to a rough wall of concrete.

Skimming Plate: A cast iron plate used to separate from the molten metal the small amount of a slag which comes out of the furnace therewith.

Skin: A thin coating formed during the cooling of cast metals.

Skin Friction: The friction between the outer surface of a pile or caisson and the surrounding materials.

Skinned Bolt: A bolt from which the threads have been stripped.

Slab: A flat, relatively thin, mass of wood, stone, concrete, or metal.

Slab Tie: A tie made from a slab.

Slabbed Tie: A tie sawed on the top and bottom only.

Slack: Not tightened; that portion required to be taken up to make a structure rigid. To loosen.

Slag: Cinder. The molten substance, other than the metal under treatment, consisting of acid or basic oxides which may be composed of the gangue of the ore combined with a flux (usually lime) in smelting operations; or of substances (usually lime and iron oxide) introduced for the purpose of effecting or assisting in the purification process.

Slag Cement: Same as "Puzzolan Cement" (a variant of "Pozzuolana Cement," a true natural cement made from volcanic ash and slaked lime.) In this country blast-furnace slag is substituted for the volcanic ash and the product is called "Puzzolan Cement."

Slag Concrete: A concrete composed of cement, sand, water, and slag from the blast furnace.

Slag Sand: Slag ground to the consistency of sand and used to replace sand for mortar or concrete.

Slake: To become disintegrated by the action of water or moisture.

Slaked Lime: A lime that has been mixed with water, or hydrated.

Slaking: The action of the air or water in producing disintegration.

Slapped Cement: Cement mortar thrown against a structure, as used in rough casting a house.

Sledge: A heavy hand hammer having a long handle for use by both hands.

Sledge Hammer: A medium-sized head of a sledge mounted on a short, thick handle. See "Sledge."

Sleeper: A railroad cross tie of wood, concrete, or metal, used to support and fix the rails of a railroad track. Generally called a "Tie."

Sleeve: A hollow cylinder or tube, used to connect round bars, bolts, shafting, etc.

Sleeve Coupling: A permanent connection in which the coupling consists of a wide band of metal extending over both ends of the shafts to be joined.

Sleeve Joint: An expansion joint in conduits, pipe lines, etc., in which the parts fit into a common sleeve.

Sleeve Nut: A sleeve having a right-hand thread at one end and a left-hand one at the other.

Slide, or Land Slide: A displacement of an unstable earth bank due to gravity and saturation.

Slide Rule: An instrument for making rapid computations mechanically, consisting of two or more sliding or revolving parts bearing graduations based on the logarithms of the numbers shown.

Slide Valve: A valve having a reciprocating motion, used in engines to open successively the admission and the exhaust, ports.

Sliding Bearing: A bearing constructed so that one part slides on another.

Sliding-ends: The ends of a bridge resting on a sliding bearing.

Sliding Friction: The resistance offered by a surface to another surface sliding over it.

Sliding Pulley: A pulley with a clutch mechanism.

Sling: A closed loop of wire, chain, or rope for convenient passing under a body and attaching to the hook of a derrick tackle for the purpose of hoisting.

Sling Chain: Same as "Hook and Ring Chain." -- A chain with a hook at one end and a ring at the other.

Sling Dogs: A pair of dogs that have the outer ends of a cable sling fastened to the straight ends of the dogs.

Slip: An earth slide. A long, narrow water space between two wharves or piers.

Slip Joint: Same as an "Expansion Joint." -- A joint in which movement for expansion and contraction is allowed.

Slogging Chisel: A heavy chisel used for cutting off bolt heads.

Slogging Hammer: A very heavy hammer-head on a long handle used in past times for the, hand-driving of rivets.

Slop Brick: An old-time brick made by depositing puddled clay in moulds and smoothing off the top with a wet stick run over the edges of the mould.

Slope: The inclined face of a cutting or of an embankment.

Slope Stakes: Slope stakes or toe stakes are stakes set on the sides of a proposed cut or fill in order to indicate the position of the top or the toe of the slope.

Slope Wall: A thin wall of concrete or of flat stones laid upon the face of a sloping bank of earth to protect it from the erosive action of water.

Slot: An oblong hole cut through a piece of metal, plank, etc. A groove cut in an axle or shaft to receive the key of a pulley or gear.

Slot Washer: A check washer having a slot cut at one side of the hole so that when the nut is tightened a nail can be driven through the slot, thus preventing the nut from turning.

Slotted Eye: An oval eye in the end of an eye-bar in place of the usual round hole.

Slotting: The act of cutting a slot.

Slotting-machine: A machine for cutting slots.

Slow-setting Cement: A cement that sets in from one to eight hours.

Sluice: An artificial channel for conducting water. To wash away earth or gravel by means of a swift stream of water.

Slumy: Consisting of light gravel and silt.

Small Ashlar: Ashlar blocks less than one foot thick.

Small-ashlar Masonry: Cut-stone masonry in which the stones are less than one foot thick.

Smelt: To extract the metals from an ore by heating in a reduction furnace, usually by means of coal, coke, or charcoal.

Smith's (C. Shaler) Formula: A formula for long timber columns, viz.:

wherep = ultimate compressive resistance in pounds per square inch
l = length of column in inches
d = least side of column section in inches

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

Smooth Fracture: A fracture either without any projections or having very few of them.

Snag: A tree, or portion thereof, having one end resting on the bed of a river or lake and the other end at or near the surface of the water.

Snake: To drag or haul, especially by a chain or rope fastened to one end of an object such as a log. A defect in rolled metal.

Snap: A tool used in field riveting to form the head of the rivet. It consists of a hammer-like head on a handle and having one of its faces hollowed out to give the desired shape to the rivet head. By placing this on the hot metal and striking it with a sledge, the rivet end is forced to conform to the shape of the hollow. Also a spring catch as in a snap-hook. To break suddenly with a short fracture.

Snap-head Rivet: A rivet having its head formed by a snap.

Snap Link: An open link with a movable part operated by a spring, used to connect chains.

Snatch Block: A pulley block with one side capable of being opened for the insertion of a rope. It is used principally to change the direction of a running line.

Snatch-block Sheave: The grooved wheel in a snatch-block.

Snipping: Chipping off, as with a tool struck by a hammer. Cutting off quickly with a pair of snips.

Snips: Small, stout hand shears used for cutting sheet metal.

Snub: To check suddenly as in the case of a swiftly moving rope by taking a turn around a post or tree.

Snubbing Line: A line or rope carried on the forward end of a barge or raft, used to pass around a post so as to check the momentum of the floating mass.

Snubbing Post: A post used for snubbing or attaching loosely a line to check the motion of a boat.

Soaking Pit: A pit in which steel ingots are placed immediately after casting so that the mass of the ingot may acquire a uniform temperature before rolling.

Soapstone: A variety of steatite.

Socket: A cavity or an opening specially adapted to receive and hold some correspondingly shaped piece. Also the metal piece having a socket for the reception of a tool or shank of some tool.

Socket Drill: A drill having a shank that fits into a socket.

Socket Mortar Hoe: A hoe having a socket-shank and a very heavy solid blade.

Socket Wrench: A wrench having a handle and shank with a recess in the latter to fit the nut.

Soffit: The lower surface of an arch.

Soft Steel: Same as "Low Steel" (or "Mild Steel") -- A soft steel containing a small amount of carbon-less than one-fourth of one per cent.

Soft Wood: An arbitrary term for wood from coniferous trees.

Solder: A compound of different metals of low fusing temperatures which when melted is used to unite pieces of other and harder metals such as copper, brass, or sheet tin.

Solder Joint: A joint made by soldering two pieces together.

Soldering Iron: A tool with a pointed or wedge-shaped bit, made of copper, having an iron shank and a wooden handle, used for applying solder while hot.

Soldering Pot: A small, portable, furnace having a clamp to hold wires that are to be soldered together and a pot to hold the melted solder. Used by linemen.

Sole Plate: A plate riveted to the bottom flange of a plate girder to bear on the masonry plate.

Solenoid: An electrical conductor wound in the form of a helix with a straight axis. When carrying an electric current it acts as a bar magnet.

Solenoid Brake: A combination of a solenoid and a movable iron core which is drawn into the helix when the electric current is flowing, thereby actuating the brake mechanisms.

Solid Arch: An arch which has no openings or deep recesses in its arch barrel, and which is composed of one material or aggregate.

Solid Spandrel Arch: Same as "Spandrel Filled Arch."

Solid Steel Floor: A floor composed of steel beams and steel plates, such as flat, buckled, or trough plates.

Solid Web: A web composed of one or more solid plates.

Solitary Bent: A single bent of a trestle that is not attached to either adjacent bent except by the girders of the deck.

Solvent: A fluid, such as water or alcohol, capable of dissolving substances.

Sound Knot: A knot in timber, which is solid across its face and as hard as the wood surrounding it.

Sounding: Measuring the depth of water. Also measuring the depth, below the ground surface, of bed rock or other strata.

Sounding Rod: A rod or pipe used for making soundings by pushing or driving it into the soil.

Soundness of Cement: A term denoting freedom from expanding, contracting, cracking, or checking in setting of cement.

Spacer: An iron casting usually spool-shaped with a hole through its axis, used to separate beams or girders when two or more of them are used to form a member.

Spacing Punch: A punch with an arm extending horizontally and having on the end of this arm a small tool, called a spotter, which engages a template working on a frame, to which is attached the sheet to be punched. When the frame is moved so that the spotter enters the hole in the template, the punch acts.

Spacing-table: A movable table with a gauge on one side, used in shops for multiple punching work.

Spacing Washer: Same as "Packing Washer" -- A washer used between timbers to provide an open space between them when they are drawn together and bolted. The object in using them is to permit of a circulation of air between the sticks.

Spade (in concreting): To work the mortar to the face of the concrete by ranning a spade up and down next to the form. A digging tool.

Spall or Spawl: A small piece of stone chipped from a larger one.

Spalling Hammer: A heavy axe-like hammer used for roughly dressing stones.

Span: The distance between two supports holding up a structure. The structure itself that rests on the supports, as a span of a bridge. To reach from one support to another by means of a structure.

Span Dogs: Same as "Ring Dogs." -- A pair of dogs connected by a ring.

Span-length: The distance from centre to centre of supports.

Spandrel: The space from abutment to abutment in an arch bridge extending from the top of the arch masonry to the top of the roadway.

Spandrel Braced: In the form of a trussed arch, in which the top chord is horizontal and the bottom chord is arched.

Spandrel Braced Arch: See "Spandrel Braced."

Spandrel Column: A column resting on the extrados of an arch and supporting the roadway above.

Spandrel Filled Arch: An arch in which the spandrels are filled with earth or other materials.

Spandrel Hangers: Hangers extending from the intrados of the arch to a longitudinal beam forming part of the lower roadway.

Spandrel Wall: A form of retaining wall built on an arch barrel to retain the spandrel filling.

Spanish Windlass: An extemporized purchase made by winding a rope around a roller and inserting a lever in a hitch or bight of the rope. By heaving round the lever a considerable torsional moment is produced.

Spanner: A wrench for coupling and uncoupling hose.

Sparry: Pertaining to the carbonate of iron.

Spathose: Having an even lamellar or flatly foliated structure.

Spatula: A broad, flat, paddle-shaped blade of wood or metal used for smoothing, scooping up, and stirring soft materials.

Spear-heat Bit: A bit having a spear-shaped end.

Specific Gravity: The ratio of the weight of a unit volume of a substance to the weight of a like volume of the standard substance, such as water.

Specifications: That part of a contract describing the details of construction and giving directions, restrictions, etc.

Specimen Test: A test of a portion of the material to be used in the construction of a structure.

Specular: Having a lustrous appearance, a term descriptive of a variety of hematite and also a variety of pig iron.

Spelter: Crude zinc before refining.

Spider: A low tripod; the internal frame or skeleton of a gear wheel on which a cog wheel may be bolted, shrunken, or cast. The group of rods connecting the conical rollers to the central casting in a rim-bearing swing span.

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

Spiegeleisen: Pig iron that contains from ten to thirty per cent of manganese.

Spike: A large nail or pin generally made of iron; to fasten with spikes or large nails.

Spike Knot: A knot in timber which knot is sawn in a lengthwise direction.

Spike Maul, or Track Maul: A maul having one end long and tapering, used for driving railroad spikes.

Spile: Incorrectly used for "Pile."

Spin Gear: Same as "Idle Gear." -- A wheel which runs loosely on its shaft.

Spindle: A short shaft carrying a wheel. A vertical member in a hand-rail, also called "Baluster."

Spiral: The curved path of a moving point rotating about an axis with a varying radius.

Spiral Curve: Same as "Spiral." Also "Easement Curve." -- A curve of gradually changing radius for passing from a tangent to a circular curve. Used in railroading to ease the train shock that comes from the changing of the direction of motion.

Spiral Gear: A gear having teeth arranged spirally, so as to mesh with a worm.

Spiral-riveted Pipe: A pipe made of long, narrow, steel plates twisted into a spiral form and riveted together.

Spiral Slide Rule: A slide rule of the revolving type. It consists of a hollow sleeve having graduations and being capable of sliding along and revo lving around a continuous cylinder which is held stationary by a handle. The scale on the sleeve is arranged in the form of a spiral, hence the name.

Spirit Level: A long block of wood or a metal frame of similar size and shape holding a short, slightly curved glass tube closed at the ends and nearly filled with ether. The bubble, thus produced, will come to the center of the tube when the apparatus is level.

Splasher: A guard placed over a wheel to prevent oil or water from being thrown on persons or neighboring objects.

Splay: To widen or spread out as in the wing walls of many culverts.

Splice: To unite two pieces firmly together. The parts used in making the union.

Splice Bar: The short bar used for making the joints in railroad rails.

Splice Joint: A joint formed by using scabs or splice bars or plates to make the connection between the two parts.

Splice Plate: A plate used in splicing or joining two parts of a member.

Spliced Pile: A pile composed of two or more sticks joined with scabs.

Splicing Shackle: A shackle in the end of a length of chain through which the end of a rope is taken and spliced.

Spline: A thin wooden strip or filler for inserting in cracks between planks.

Split Gear: A gear wheel made in halves for convenience in mounting.

Split Pulley: A pulley made of two parts, held together by bolts, and so arranged that it can be removed from its shaft without disturbing the latter.

Split Switch, or Point Switch: A switch having a point on one rail which fits closely against the other rail, thus giving a continuous track effect.

Split Tie: A tie made from a tree of such size that, by splitting, two or more ties can be made from a section.

Splits: Short, flat strips of steel.

Splitting Chisel: A wedged-shaped chisel.

Spoke Wheel: A wheel having spokes instead of a solid web.

Sponge: Metal in a porous form.

Sponginess: The state or character of being soft, porous, or spongy.

Spool: A short cylinder with a longitudinal hole through its centre; also a niggerhead on a hoisting engine.

Spoon: A small bowl-shaped piece of metal with a rod for a handle used to clean out inaccessible holes such as a drill hole.

Spout: Same as "Chute."

Spread: To flatten out; to widen.

Spread Foundation: Similar to "Footing." Also the spread portion below steel cylinders for piers; the spreading being done after the cylinders are sunk to place.

Spread Span: A span at the end of a bridge so spread out at the shore that diverging tracks may be run thereon.

Spreader: A tool for spreading refractory metal over a furnace bottom.

Spreading-rate: The rate a paint or paint material as used is brushed out to a continuous uniform film, measured by the area which a unit volume will cover.

Spring: An elastic body used to reduce the force of impact. To rise or move quickly. A flow of water from the ground.

Spring Balance: An apparatus for weighing articles by noting the compression of a helical spring.

Spring Clip: A clip worked by a spring for holding sheets of paper.

Spring Dolly: A dolly having a heavy hammer head attached to a long handle. Each end of the hammer has a cup to receive the heads of the rivets during driving.

Springer: The lowest course of a stone arch lying immediately on the top course of the support.

Springing Line: The line connecting the lower edges of the springers in a masonry arch; or, in general, the line connecting the two opposite points where the curve of the intrados intersects or becomes tangent to the face of the supports of the arch.

Springing-points: The points at the ends of the springing line of an arch.

Springing Stone: The first course of stone below the springing line in an arch.

Sprocket: One of the projections on a toothed wheel which engages a sprocket chain.

Spud: A small spade; a vertical timber used for anchoring scows.

Spudding Bar: A bar used to drill a hole through the overlying earth to rock, in order to make an entrance for the rock drill.

Spur Gear: A gear having teeth arranged around either the concave or convex surface of a cylindrical wheel and in the direction of a radial plane passing through the axis.

Spur Pile: Same as "Batter Pile." -- A pile driven at an inclination to the vertical.

Spur Track: A short track leading from the main track and connected to it at one end only.

Spur Wheel: Same as "Gear."

Square: A four-sided, plane, rectilinear figure having equal sides each at right angles to the two adjacent. A tool used by carpenters, draughtsmen, and others for laying out a right angle.

Square Coupling: A form of coupling box, consisting of two longitudinal halves, having a squared hole to fit the squared ends of the two shafts to be connected.

Square Crab or Square End Crab: A crab having the ends of the shaft squared to receive the cranks or handles.

Square Crossing: A crossing in which the intersecting centre lines are perpendicular to each other.

Square Droved Dressing: A finish in stonework made by fluting the face perpendicular to the lower edge of the stone.

Square-end Column: A column bearing on its squared ends.

Square End Crab: Same as "Square Crab."

Square File: Any file having a square cross section.

Square Hewed Pile: A timber pile trimmed with an adze into an approximately square section.

Square Joint: A timber joint in which the ends are brought squarely together.

Square Nut: A nut having four sides in the form of a square.

Square Punch: A machine for punching square holes.

Square Thread: A thread having a square or rectangular cross-section.

Square-threaded Screw: Any screw having square threads.

Squared-range Masonry: Masonry composed of squared stones laid in ranges or courses of varying thickness.

Squared-stone Masonry: Masonry composed of stones roughly dressed and squared on beds and joints. Similar to ashlar masonry, but not having as close joints.

Squeegee: A wooden scraper having a rubber edge. Used for smoothing off the grout in constructing brick pavements.

Stability: The ability to resist change of position.

Stable: Standing firmly in place.

Stable Equilibrium: That condition of a body when a slight displacement of it is followed by a return to the original position.

Stadia: A method of measuring distances by noting the intercepts on a stadia board, made by the stadia wires in the telescope of a surveyor's transit.

Stadia Rod: A rod divided into feet and tenths with special markings which are visible at long distances. It is used in connection with the stadia wires of the transit to read distances directly. Sometimes a level rod is employed as a stadia rod. Special stadia rods are frequently termed stadia boards.

Stadia-wires: Two horizontal wires placed equidistant from the centre cross wire of the telescope of a transit.

Stage: A platform, either fixed or swinging, used in erection of high structures; a scaffold; also the interval between two platforms used in shoveling, throwing, or lifting excavated material.

Stagger: To arrange in a zigzag order, as the staggering of rivets.

Staggered Riveting, or Zigzag Riveting: Rivets set in zigzag order, or so spaced that the rivets in one row are opposite the centres of the spaces of the adjoining rows.

Staging: Same as "Stage," used collectively.

Stainer: One who applies stain. A coloring matter.

Stake: A short, flat-sided piece of wood sharpened at one end, used for marking out on the surface of the ground where work is to be done and what it is.

Stalk: A spiked iron rod forming the centre for a core; one of the upright side pieces of a ladder.

Stamp: A die; to make an impression on a surface by means of a die.

Stamping Hammer: A small hand hammer having the initials of the firm's name on the pointed end, used by timber inspectors and the like to stamp material which has been inspected and accepted.

Stanchion: An upright post supporting a roof.

Standard: Any measure of extent, quantity, quality, or value established by law or by general usage.

Standard Gauge: The adopted standard distance between the inner faces of the balls of rails in a track; equal to four feet eight and one-half inches. This was established by agreement between all of the railroads so as to interchange cars.

Standard High Water: An arbitrary high-water elevation either assumed or fixed by the War Department or some other authority.

Standard Knot: A sound knot in timber not over one and a half inches in diameter.

Standard Low Water: An arbitrary low-water elevation either assumed or fixed by the War Department or some other authority.

Standard Sieve: A term applied to sieves used in cement testing, one size having one hundred meshes per lineal inch and the other two hundred meshes per lineal inch.

Standard Thread: A thread having the shape of spiraling and a pitch conforming to some standard such as the American Bridge Company's Standard Thread.

Standardize: To regulate by a standard.

Standardized Tape: A tape that has been compared with the official standard of length.

Standing Block: A pulley block fixed to some permanent support.

Standing Bolt: Same as a "Stud Bolt."

Standing-end: As applied to a rope, it is the end made fast to a block or other fixed point.

Standing Pile: A pile which stands without bracing.

Standing Rope: A rope fastened permanently, as a guy for a derrick.

Staple: A standard; a piece of wire or metal bent into the shape of the letter U, and having its ends sharpened to a point so as readily to penetrate wood.

Star Section: A section of a member having the shape of a four-pointed star.

Star Strut: A strut formed of either two or four angles placed back to back. The two-angle form is not a satisfactory type, as it fails to develop as high an ultimate strength as might properly be anticipated.

Starling: A cutwater; the projecting end of a bridge-pier, usually so shaped as to allow ice, drift, ete., to strike it without injury.

Starling Coping: Same as "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.

Starred Angles: A pair of angles placed corner to corner with legs outstanding and held in position by tie-plates riveted thereto at intervals.

Static: Pertaining to or designating bodies at rest or forces in equilibrium.

Static Deflection: Deflection due to a quiescent load.

Static Equilibrium: That condition of a body at rest in which the resultant of all the forces acting thereon is zero. There are three types of Static Equilibrium, viz., Stable, Unstable, and Indifferent.

Static Load: Same as "Dead Load." -- The weight of all the parts of a bridge itself and anything that may remain upon it for any length of time, such as tracks, water mains, telephone and telegraph lines, snow, dirt, moisture, etc.

Static Stress: Same as "Dead Load Stress." Stress due to a quiescent load. -- The stress resulting from the application of a static load. Generally means the stress produced in a structure by its own weight.

Statics: That branch of mechanics which deals with a balanced system of forces acting on bodies at rest.

Stationary Engine: An engine that rests on a fixed foundation and is not movable.

Stave: One of the boards joined laterally to form a barrel or hollow cylinder. Pieces of wrought iron welded together as a basis for making shafts. To swell up the end of a tube.

Stay: A rope used to support a vertical pole or mast, such as a derrick mast. To support by means of stays.

Stay Bolt: A threaded rod or belt binding together opposite plates to enable them to sustain each other against opposing pressure, as the stay bolt in a boiler.

Stay Pile: A pile connected or anchored by land ties with the main piles in the face of pile work.

Stay Plate: Same as "Batten Plate." -- A stayed plate at the ends of a compression member.

Stay Rod: A stiffening rod used in the interior of a boiler or cylinder.

Stay Wire: Same as "Guy Wire."

Stayed Link Chain: A coil chain in which all the links are cross-braced. Called also a "Stud Link Chain"

Steam-chest: The chamber, adjoining the cylinder of a steam engine, in which the slide valve works.

Steam Condenser: A condenser used for steam.

Steam Crane: A crane operated by steam power.

Steam-cylinder: A cylinder in which steam does work by expanding against a movable piston. The chamber of a steam engine in which the force of steam is exerted on a piston.

Steam Dredge: A dredge operated by steam.

Steam Engine: An engine in which a portion of the heat energy of the fuel is conveyed to the cylinder by means of steam, which expands behind the piston and drives it forward.

Steam Gauge: An instrument for determining and indicating the pressure of steam.

Steam Hammer: A powerful machine hammer consisting of a steam cylinder mounted between guides, a piston, a piston rod with a heavy ram at its lower end, and an anvil at the base of the supporting frame. Steam is admitted to the cylinder by suitable valve mechanism and raises the piston in all cases, while in some it gives an added impulse to the natural fall of the ram. Sixty to eighty blows per minute can be delivered by this apparatus.

Steam Hoist: A hoist operated by steam.

Steam Hose: A hose conveying steam.

Steam Jacket: The jacket placed around a steam pipe or a cylinder of an engine.

Steam Jet: A flow of steam from an orifice.

Steam Port: Same as "Port" -- The narrow slot in the ends of a cylinder for the passage of steam.

Steam Riveter: A shop riveter driven by steam.

Steam Siphon: A siphon in which a partial vacuum is made and maintained by the condensation of steam.

Steamboat Jack: A ratchet jack similar to and operating on the same principle, as a steamboat ratchet, but with bearing shoes at the ends of the screws so that a pressure may be exerted between two objects or parts of a structure.

Steamboat Ratchet: Same as "Boat Ratchet." -- An apparatus for pulling, consisting of a sleeve having internal, opposing threads at the ends and a ratchet and handle for turning the same. Suitably threaded rods with links and hooks at the outer ends screwed into the sleeve. The turning of the sleeve screws up on the rods causing them to approach each other.

Steatite: Massive talc or soapstone, a hydrous magnesian silicate.

Steel: A modified form of iron, not occurring in nature, made from pig iron by oxidizing most of the carbon.

Steel Joists: Joists made of steel.

Steel Pile: Piles made of rolled steel rods or shapes.

Steel Press: A machine used in the manufacture of steel for pressing or squeezing out the slag. The action thereof may be continuous or intermittent.

Steel Tape: A tape made of steel. Used for accurate work.

Steining: The brick or stone wall lining a vault.

Stem: The handle of a tool; the projecting rod of a slide valve; a narrow portion of an object connecting two larger portions. To hold back, to resist.

Stem-section: That portion of an object containing the stem.

Step Stone: The stone which forms a step in foundations.

Stepped: Formed into a series of steps.

Stepped Gear: A form of gearing in which each tooth or cog on the face of a wheel is replaced by a series of smaller teeth.

Stepped Pulley: A pulley having a stepped face or parts with different diameters, thus permitting of a shifting of the belt and the transmission of different speeds.[Sometimes called "Cone Pulley."]

Stereotomy: The science of cutting solids into certain shapes. Generally applied to stonework.

Sterro Metal: A brass containing from 1.77% to 4% of iron.

Stiff: Rigid, not easily bent, not working easily.

Stiff Leg: A leg capable of taking compression.

Stiff Leg Derrick: A derrick where stiff legs, usually of timber, take the place of guy lines for staying the mast. These stiff legs are attached to horizontal timbers which in turn are fastened to the bottom of the mast.

Stiffened Suspension Bridge: A suspension bridge with stiffening trusses.

Stiffener: A secondary member, usually an angle, attached to a plate to prevent buckling.

Stiffening Angles: Angles riveted to the web of a girder to stiffen it against buckling.

Stiffening Girder: A girder employed to give vertical stiffness, as in the case of a suspension bridge.

Stiffening Rib: A rib run longitudinally along the curved trusses in a wooden bridge. Also the webs in a shoe, casting, or baseplate.

Stiffening Strut: A strut used to overcome a buckling tendency or to fix an intermediate point of a post or column and thus reduce the value of l over r.

Stiffening Truss: A truss used in connection with a suspension cable to distribute the load over the length thereof.

Stirrup: In reinforced concrete beams or slabs, a U-shaped bar inserted for the purpose of resisting diagonal tension, or so-called shear.

Stitch Rivets: Rivets placed at intervals between two component parts to hold them together and give lateral stiffness.

Stock: The raw material used for charging a furnace. The foundation for the anvil of a power hammer. An apparatus or tool for holding another tool.

Stock Ramming: A process for stopping leaks in a cofferdam by ramming clay through a hole cut; in the supporting timbers.

Stone: A small piece of rock. A piece of rock hewn or shaped for specific use.

Stone Boat: A boat or barge which carries stones.

Stone-breaker: A machine for crushing stones.

Stone Bridge: A bridge built of stones laid in mortar.

Stone Cutter: A workman skilled in the art of cutting and dressing stone.

Stone Drill: A bar used to cut holes in stones and rocks.

Stone Girder: A lintel.

Stone Hammer: A mason's hammer, used for chipping stone.

Stone Planer: A machine for smoothing the surface of a flat stone.

Stone-polisher: Either a machine or a man that polishes the face of a stone, after it has been smoothed, by the use of powdered pumice-stone and water.

Stone-ring: Same as "Belt." -- A course of stones or bricks projecting from a structure, generally lying in a horizontal plane.

Stone Saw: A tool or machine for cutting stone, consisting of a flat blade of iron having a reciprocating motion, and fed with sand by a stream of water, the sand doing the cutting.

Stop-cock: Same as "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.

Stop Valve: Same as "Gate Valve." -- A valve having a slide or gate placed at right angles to the flow of the liquid and arranged to draw completely to one side when opened, thereby offering little obstruction to the flow, but completely stopping it when closed.

Stop-water: A plug of soft wood driven tightly into a hole at the joint of a scarf which when wet swells and prevents leakage through the said joint.

Stoppered Splice: A short piece of rope spliced into a longer rope to form a stopper or check to prevent the rope from running out of a block.

Storm Cable: An extra strong cable used to give additional strength or anchorage during severe wind-storms.

Stove Bolt: A small bolt having a rounded head, notched for a screw driver, at one end and a square nut at the other.

Straight Abutment: An abutment that has only one wall, which is generally at right angles to the longitudinal centre line of the structure.

Straight Dolly: A cup-shaped dolly with a straight head and shank.

Straight-edge: A thin bar of wood or steel used by draughtsmen for drawing straight lines. Also a bar or narrow board having at least one straight edge, used on construction work to obtain a flat and level surface.

Straight Line: The shortest distance between two points, a line which has no curves nor angles.

Straight-line Formula: One of the several types of formulae used to express the resistance of columns. In this type the relation of the strength of the. column to its length divided by its least radius of gyration can be represented by a straight line.

Straight Shank Drill: A drill having a straight shank, in contra-distinction to a tapered shank.

Straightening-machine: A machine used for straightening bars, beams, channels, etc.

Straightening Rolls: Rolls in a steel mill used for rerolling bars, beams, channels, etc., which had been bent during manufacture.

Strain: The deformation caused by an external force applied to any piece of material or to any bridge member. Often loosely used for stress.

Strain Sheet: Wrongly used for "Stress Sheet."

Strainer: Any device used to separate small solid particles from a liquid, such as a strainer on the end of a suction hose of a pump.

Strake: A breadth of planking; the hoop or tire of a wheel.

Strand: One of the small threads used in making rope.

Strap: A narrow band of flexible material used to encircle and hold together various articles.

Strap Bolt: Same as "Lug Bolt." -- A round bolt to which is welded a flat iron bar.

Strap Hinge: Same as "Joint Hinge." -- A hinge having long leaves joined at their large ends.

Strap Joint: See "Strap Hinge."

Strap Rail: An iron strap bolted to a longitudinal wooden stringer to serve as a rail.

Stratification: A geological formation consisting of layers or bands Stratum: A natural or artificial bed of rock or earth.

Straw-boss: Same as "Pusher." -- A sub-foreman, in charge of one gang, who sees that the men do the work assigned to them as rapidly as possible.

Strength: The capacity to resist distortion or disintegration.

Stress: An internal distributed force that resists the change in shape and size of a body subjected to external forces.

Stress Couple: A pair of equal and opposite stresses lying in the same plane.

Stress Diagram: A skeleton drawing of a truss, upon which are written the stresses in the different members. Also called "Diagram of Stresses."

Stress Sheet: Same as "Stress Diagram."

Stretcher: In masonry, a stone laid with its long dimension parallel to the wall.

Stretcher Course: A course of masonry consisting entirely of stretchers.

Strict Heart Tie: A tie having no sapwood.

Striking: Hitting with a hammer or sledge, as striking a drill. Removing camber blocks or arch forms.

Striking Hammer: A quarryman's hammer for striking a rock drill.

Striking of Arch: Knocking out the wedges and lowering the centres, thus making the arch self-supporting.

Striking Wedge: One of the wedges inserted temporarily to support centres or falsework and knocked out after the work is completed.

String Course: A narrow ornamental course carried around a structure.

String Packing: Any packing put up in the form of cords.

String-pieces: The sloping beams of a stairway which support the treads.

String Polygon: Same as "Equilibrium Polygon." -- A term used in graphic statics to designate the polygon drawn through a system of non-concurrent forces in order to determine the position of the resultant thereof. The sides of the polygon are made parallel to the rays of an accompanying force polygon.

Stringer: A longitudinal member extending from panel to panel of a bridge and supporting the ties or the flooring.

Stringer Bolt: A bolt used to connect parallel wooden stringers that are laid side by side, a washer or separator being placed between each pair of stringers thus connected in order to let the air circulate between them and prevent decay. Usually these stringers are bolted together for the purpose of forming one member, or a composite stringer.

Stringer Bracing: Diagonal bracing in the plane of the. upper flanges of the stringers.

Stringer Packing: The arrangement of stringers under a track on a trestle.

Stringer-spacing: The distance between the centres of stringers and their location with reference to the centre line of structure.

Strip: A narrow board. To remove the timber forms from concrete. To tear off, as to remove the threads from a bolt or the teeth from a cog.

Striped Dressing: A dressing in stonework wrought by a mason's point or punch producing parallel grooves.

Stripping: Removing forms from concrete; tearing off anything.

Stripping-bill: A local term for a bar having a curved end, used in removing forms.

Stripping of Gears: The tearing or shearing off of the teeth of gear wheels or portions thereof.

Stroked: A form of masonry dressing, also called "Droved."

Stroked Dressing: Same as "Droved Dressing." -- A finish in stonework wrought with a broad chisel or hammer in parallel flutings across the face from end to end.

Structure: A general term for anything that is built or constructed, as a bridge or a building. The arrangement and organic union of the parts in a body or object.

Strut: A bridge member carrying compression.

Stub Abutment: Same as "Straight Abutment."

Stub Switch: A switch with the ends of the rails of the main track and switch track cut off square, the switch rails being firmly fastened to a chair and the main line rails that lead toward the switch moving with a sliding motion. These switches are used only at yards.

Stud: A short projecting pin. An upright member in a wall to which the laths are attached.

Stud Bolt: A bolt with a thread cut at each end in order to be screwed into a fixed part at one end, leaving the other end projecting so as to receive a nut.

Stud Link Chain: Same as "Stayed Link Chain."

Studding: Same as "Stud."

Stuffing Box: A device for securing a steam-tight, air-tight, or water-tight joint about a movable rod. It consists of two parts or glands held together by bolts and so arranged that packing of some kind can be inserted between the glands and compressed, by means of tightening the nuts on the bolts, against the movable rod.

Stump Joint: A joint having a stump to prevent folding except in one direction, as in a folding rule.

Sub-Contract: A contract which is sublet.

Sub-Contractor: One who takes a part or the whole of a contract from the principal contractor.

Sub-diagonal: A secondary member connecting the mid-point of a main diagonal with an adjacent panel point.

Sub Diagonal: An intermediate web diagonal joining a chord with a main diagonal.

Sub-divided Pratt Truss: Same as"Petit Truss." -- A modified form of the Pratt truss having subdiagonals. See Figs. 22c, 22d, 22e, and 22f.

Fig. 22cFig. 22d
Fig. 22eFig. 22f

Sub-divided Warren Truss: See "Subdivided Warren Truss."

Sub-foreman: A foreman under the general foreman who is in charge of more than one gang of men.

Sub Grade: The bottom surface of the ballast or pavement.

Sub-letting: The re-awarding of a contract or a portion thereof by the successful bidder to another party.

Sub Post: A secondary post used in a subdivided panel.

Sub-punch: To punch a hole smaller than the rivet to be used, so that the injured metal may be removed by reaming out to size.

Sub-sill: Same as "Mud Sill." -- A sill placed on short cross blocks resting on the earth, to support a framed bent.

Sub-soil: The stratum of earth lying immediately under the surface soil.

Sub-strut: A sub-diagonal carrying compression.

Sub-tie: A tension member in a subdivided panel of a truss.

Sub Vertical: The upright member in a subdivided panel running from midpanel point to the chord.

Subdivided Panel: A panel divided by a sub-diagonal or hanger.

Subdivided Warren Truss: A Warren truss with verticals having subdiagonals and subverticals. It bears the same relation to Fig. 22 1 as the Petit truss [e.g. Fig. 22c] does to the Pratt truss .

Fig. 22 l (Warren)Fig. 22c (Petit)

Submerged Pier: See "Pier."

Substructure: The part of any construction which supports the superstructure. The piers, pedestals, and abutments of a bridge or trestle.

Suction: A drawing up of a liquid by the production of a partial vacuum in a space connected with the said fluid.

Suction Hose: A reinforced rubber hose running from a pump to the water supply.

Suction Pipe: The pipe running from a pump to the water supply.

Suction Pump: A pump that raises water by creating a partial vacuum or suction.

Sudden Stress: The stress resulting in a member from the sudden application of a load thereto.

Sulphur: An elementary substance which occurs in nature, characterized by a yellow color, a brittle, crystalline structure, a resinous lustre, and strong acrid fumes given off during combustion. Used sometimes in bridgework for filling around bolts in masonry.

Sump, or Sump-hole: A depression or hole in a pier foundation, used to collect drainage water so that it may be pumped out; also a hole under a building or in a tunnel for the same purpose.

Sump-hole: Same as "Sump."

Super-elevation: The height of the outer rail above that of the inner rail on curved tracks. The rails are thus placed in order to overcome the tendency of a car or train going at high speed to fly off the track. The super-elevation is governed by the speed and degree of curvature.

Superintendent: The person having complete control of a piece of work.

Superstructure: That portion of a bridge or trestle lying above the piers, pedestals, and abutments. The part of a structure which receives the live load directly.

Supplement: An addition to anything to make it complete. To add anything for that purpose.

Supplementary: Being in the nature of a supplement.

Supply Shaft: A passageway in a crib and caisson for the transferring of supplies.

Supporting Machinery: Machinery used in connection with the operation of a lift span.

Surbase: A border or moulding above a base.

Surcharge: To overcharge. The earth that lies both above and behind a retaining wall.

Surface: The condition of a track as to vertical evenness and smoothness.

Surface Joint: A connection between metal plates by joining the edges with flanges or laps riveted or soldered to the parts.

Survey: To determine the boundaries, extent, position, elevation, etc., of a portion of the earth's surface by means of lineal and angular measurements. The result of such a process is also termed a survey, as is also the process itself.

Surveying: The art of making surveys.

Surveyor: A man skilled in the art of surveying.

Surveyor's Level: Similar to "Engineer's Level."

Suspended Floor: A floor attached to suspension cables or to girders by hangers.

Suspended Span: A span connecting two cantilever arms and supported wholly thereby.

Suspender: A hanger used to suspend a floor from a cable or from a truss or other object.

Suspender Cable: A hanger cable in a suspension bridge for supporting the floor system.

Suspension Bridge: A roadway suspended from chain or wire cables, usually hung between massive towers of masonry and securely attached to abutments. Also called a wire bridge.

Suspension Cable: One of the cables forming the support of the floor of a suspension bridge.

Suspension Rod: One of the rods attached to the cable of a suspension bridge to support the floor system.

Swab: A mop used for spreading tar on the surface of a concrete deck and on the bearings for paving blocks.

Swage, or Swedge: A die or former used for shaping pieces of metals, tools, etc. To shape with a swaging block.

Sway: To brace laterally or longitudinally against horizontal movement.

Sway Bolt: A bolt which fastens the sway bracing to other timbers.

Sway Bracing: Bracing transverse to the planes of the trusses; used to resist wind pressure and to prevent undue vibration.

Sway Rod: Any rod used for sway-bracing.

Sway Strut: A strut used in sway bracing.

Sweating: A method of fastening two metallic surfaces together by means of a very thin invisible layer of solder.

Swedge Bolt: A bolt having a thread and hexagonal nut at one end and elliptical recesses at the other, used by some railways instead of fox bolts.

Swedge: Same as "Swage."

Swedish Iron: A very pure wrought iron manufactured in Sweden. Very expensive.

Swelled Column: A column that is larger at the middle than at the ends.

Swing Bridge or Swivel Bridge: A span that rotates about a vertical axis, so as to provide openings for the passage of vessels.

Swing Span: A span that revolves on a centre pier or swings from an end pier to allow a passage for vessels through the bridge.

Swinging Crane: Any crane which has a boom that swings laterally.

Swinging Scaffold: A scaffold hung on ropes fastened to overhead supports.

Swipe: To strike or drive with great force.

Switch: A device for changing or shifting a portion of a track so that the train will be diverted. An apparatus for turning on and off an electric current.

Switch-back: A method or system of track construction enabling a train to climb a steep slope by zigzagging back and forth over a succession of short tracks connected with each other by switches.

Switch Bar: A bar which connects the movable rails of a switch.

Switch-signal: A signal to apprise the train crew which track the switch is set for. In the daytime a swinging arm is used and at night different colored lights.

Switch-stand: The stand on one side of a track from which a hand-thrown switch is worked.

Switching Locomotive: A locomotive used mainly for switching cars in the yards.

Swivel: A device consisting of a U-shaped bar attached to a plate having a hole in its centre through which passes the headed shank of a hook, thus permitting of an axial rotation of either part.

Swivel Bridge: Same as "Swing Bridge."

Swivel Hanger: A hanger for shafting with pivoted boxes to permit a certain amount of play and adjustment in the motion of the shaft.

Swivel Head: The upset end of the swivel hook, enlarged to prevent it from slipping through the eye in the U-shaped half of the swivel.

Swivel Hook: The half of the swivel that works through the washer or small circular plate fastened to the U-portion of the device and to which the rope or chain is attached.

Swivel Joint: A joint utilizing a swivel to permit twisting of the parts with respect to each other.

Sword: A hand tool in the shape of a small sword, used for filling with mortar the joints in masonry.

Syenite: A rock composed of feldspar and hornblende with very little or no quartz.

Sylvester-wash: The alternate applications of a solution of soap and one of alum to the dry surface of concrete construction so as to render the same impervious to water.

Symmetry: A condition of equality or balance of shape, size, and position between similar parts of a figure or body about a central axis.

Sypher Joint: Same as a "Chamfered Joint = 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