475 STANDARD ELECTRICAL DICTIONARY.S.(a) Symbol for second.(b) Symbol for space, or length; L is preferable.(c) Symbol for south-seeking pole of a magnet.Saddle Bracket.A bracket carried on the top of telegraph poles, carrying an insulatorfor the upper wire.Safety Device.(a) A device to prevent overheating of any portion of a circuit byexcess of current. It generally consists of a slip of fusible metalwhich if the current attains too much strength melts and opens thecircuit. To ensure its breaking a weight is sometimes suspended from thestrip. In one form an insulated German silver wire is wrapped around theend of the fusible strip a number of times and its end is connected toit. The other end of the German silver wire connects with the main lead,so that all the current goes through both in series. If the Germansilver wire becomes heated from excess of current the coil wrappedtightly around the end of the fusible strip melts it and opens thecircuit.(b) Lightning arresters, q. v., may be cited under this heading.Synonyms--Automatic Cut Out--Safety Fuse, Plug, or Strip.Fig. 299. COCKBURN SAFETY FUSE.Safety Fuse.A strip of metal inserted so as to form part of a circuit and of suchsize that a smaller current [than] would heat the regular wire of thecircuit dangerously, so as to cause a conflagration for instance, wouldmelt the fuse and open the circuit. As it sometimes happens that asafety fuse melts without parting a weight is sometimes hung upon it, soas to break it as it softens.Salt.A salt is a chemical compound containing two atoms of two radicals,.which saturate each other. One atom or radical is electro-positivereferred to the other, which is electro-negative. By electrolysis saltsare decomposed, the atoms or radicals separating and uniting to form newmolecules.476 STANDARD ELECTRICAL DICTIONARY.Saturated. adj.A liquid is saturated with a substance when it has dissolved all that itcan, while an excess is present in the liquid. It is possible, bydissolving some salts in hot water and allowing the solution to coolwithout access of air, to obtain a supersaturated solution. Onintroduction of a crystal of the salt, or often on mere access of air,the solution forms crystals and the liquid left is saturated.Saw, Electric.A platinum coated steel wire mounted and connected to be raised toincandescence for cutting purposes.Schweigger's Multiplier.An old term for the galvanometer as invented by Schweigger soon afterOerstedt's discovery.Scratch Brushes.Brushes for cleaning the surface of articles to be electroplated to givea good metallic surface suitable for deposition. They have often wireinstead of bristles.477 STANDARD ELECTRICAL DICTIONARY.Fig. 300. WIRE GAUZE ELECTRIC SCREEN.Screen, Electric.A large plate or a hollow case or cage of conducting material connectedwith the earth, and used to protect any body placed within it fromelectrostatic influences.If within a hollow conducting sphere an electrified body is placed, theinner surface of the sphere will be charged with electricity of oppositekind to that of the sphere, and the outer surface with the same kind asthat of the sphere. Thus the sum of the electricities called into actionby induction is zero. The two inner charges are bound to each other. Theinduced charge on the outer surface of the sphere is all that has anyeffect on objects in the outer air.If the outer surface is connected to the earth it becomes discharged,and however highly electrified the body introduced into the sphere andthe inner surface of such sphere may be, they produce no externaleffects, as they are bound one to the other.If the sphere is connected to the earth and an unelectrified object isplaced within it, such object will be perfectly shielded from theeffects of an outer electrostatic field. Perforated tinfoil or wiregauze has just as good a result. A large plate of metal connected to theearth has the same effect. The screen whether plane or hollow simplyretains a bound charge due to the field of force, thereby neutralizingit, and the electricity of the opposite sign escapes to the earth. Thusa true shielding or screening effect is produced.In the cut an experiment is shown in which an electric screen is carriedby a Leyden jar. Pith balls are suspended outside and inside of it. Bythe approach of an electrified body the outer pith balls will diverge,while no effect is produced upon the inner ones.Secondary Actions.In electrolysis the direct products of the electrical decomposition arenot always obtained at the electrodes, but products due to theirreaction on the water and other chemicals may appear. These constitutesecondary actions. Thus if a solution of copper sulphate is electrolyzedwith platinum electrodes, metallic copper appears at one pole andsulphuric acid and oxygen gas at the other. But the products ofelectrolysis by the current are copper (Cu) and sulphion (SO4). Thelatter reacting on water sets free oxygen gas and forms sulphuric acid.The latter is a secondary action.Secondary Generator.(a) An alternating current converter generating a so-called secondarycurrent.(b) A secondary battery, q. v., may be thus termed.Secondary, Movable.The term movable secondaries has been applied to rings, spheres anddiscs of conducting material, such as copper, whose behavior when nearthe pole of an electro-magnet traversed by an alternating current, havebeen studied by Elihu Thomson. Such masses are subjected to verypeculiar movements and mutual reactions. As the phenomena are due toinduced currents the above term has been applied to the masses in whichthe currents are induced.478 STANDARD ELECTRICAL DICTIONARY.Secondary Plates, Colors of.In a secondary battery of the lead plate type, the color of the platesis a good indication of the condition of the battery. The negative plateshould be brown or deep-reddish, the other should be slate-colored.Secondary Poles.Poles sometimes found in magnets existing in positions intermediatebetween the end or true poles.Synonym--Consequent Poles.Seebeck Effect.The production of a current by heating the junction of two differentmetals forming part of a circuit, or the thermo-electric production ofcurrent, is stated as the Seebeck effect, having been discovered by thatinvestigator.Selenium.A non-metallic element. It is interesting electrically on account of thechanges its electric resistance undergoes when it is subjected to light.In one set of experiments it was found that diffused light caused theresistance to fall in the ratio of 11 to 9. Full sunlight reduced it toone-half. Of the spectrum colors red was most powerful and the ultra redregion still more strongly affected its resistance.The effect produced by exposure to light is instantaneous, but onremoval to the dark only slowly disappears.A vessel of hot water was found to have no effect, showing that shortether waves are essential to the effect.Selenium Cell.A selenium resistance box. Vitreous selenium is made by keeping ordinaryselenium for some hours at a temperature of about 220º C. (428º F.)after fusing. It is placed in an electric circuit as part of theconductor.Its resistance can then be determined. It decreases in sunlight to aboutone-half its resistance in the dark.The selenium cell is used in the Photophone, q. v. Otherwise it islittle more than a subject of experiment.Selenium Eye.A model eye in which selenium in circuit with a battery and galvanometertakes the place of the retina of the human eye.Self-repulsion.When a body is electrified each molecule repels its neighbor and thecondition in question is thus designated. An electrified soap-bubbleexpands in virtue of self-repulsion.Semi-conductors.Substances which conduct static electricity poorly, but quiteappreciably and beyond the extent of leakage. The following areexamples: Alcohol and ether, powdered glass, flowers of sulphur, drywood, paper, ice at 0º C. (32º F.)479 STANDARD ELECTRICAL DICTIONARY.Sensibility.The measure of the effect of a current upon a galvanometer,or any similar case.Sensitiveness, Angle of Maximum.Every galvanometer has its angle of maximum sensitiveness, which is theangle of deflection at which a small increment of current will producethe greatest deflection. For every tangent galvanometer 45° is the anglein question. In using a galvanometer for direct reading methods it is anobject to have it work at its angle of maximum sensitiveness.Separately Excited Dynamo.A dynamo-electric machine whose field magnet is excited from an outsidesource, which may be another dynamo or a battery. Alternating currentdynamos are often of this description.Separate Touch.In magnetism a method of inducing magnetism in a steel bar. The oppositepoles of two magnets are applied at the center of the bar to bemagnetized, but without touching each other, and are drawn apart to itsends. They are returned through the air and the process is repeated anumber of times and on both sides of the bar if necessary.Separation of Electricities.Under the double fluid theory of electricity the action ofelectrification in accumulating positive electricity in one conductorand negative on the other of the excited surfaces of two conductors.Separator.India rubber bands or other forms used in batteries to keep the platesfrom touching in the cell; especially applied to secondary batteries,where the plates are so near together as to require separators toprevent short circuiting.Fig. 301. SERIES CONNECTION.Series.(a) Arranged in succession as opposed to parallel. Thus if a set ofbattery jars are arranged with the zinc of one connected to the carbonof the next one for the entire number, it is said to be arranged inseries. When incandescent lamps are arranged in succession so that thecurrent goes through one after the other they are arranged in series.The opposite of parallel, q. v., or multiple arc, q. v.; it may be usedas a noun or as an adjective.(b) See Electro-Chemical Series;(c) Thermo-Electric Series(d) Electrostatic Series;(e) Electro-motive Series.Synonym--Cascade Connection (but little used.)480 STANDARD ELECTRICAL DICTIONARY.Series-multiple.Arrangement of electric apparatus, in which the parts are grouped insets in parallel and these sets are connected in series. It is used as anoun, as "arranged in series-multiple," or as an adjective, as "aseries-multiple circuit or system."Fig. 302. SERIES-MULTIPLE CONNECTION.Service Conductors.In electric distribution the equivalents of service pipes in thedistribution of gas; wires leading from the street mains to the houses,where current is to be supplied.Serving.The wrapping or winding of a cable composed of small size wire, laidclosely and smoothly with a tool called a serving mallet, or servingblock, or by machinery. It serves to protect the cable from wear.Shackle.In telegraph lines a swinging insulator bracket for use where wires makean angle with the pole. A journal box is attached to the pole, like halfof a gate hinge. To this a short iron arm is pivoted so as to be free toswing through a considerable angle. At its end an insulator is carriedto which the wire is attached. The shackle swings into line with thewire, or takes a position for two wires corresponding to the resultantof their directions of pull.Fig. 303. DOUBLE SHACKLEShadow. Electric.A term applied to a phenomenon of high vacua. If an electric dischargeis maintained in a Crookes' tube the glass opposite the negativeelectrode tends to phosphoresce. A plate of aluminum, used also as thepositive electrode, protects the glass directly behind it so as toproduce the effect of a shadow.Synonym--Molecular Shadow.[Transcriber's note: The effect is due to the "shadowing" of theelectrons streaming past the plate.]481 STANDARD ELECTRICAL DICTIONARY.Sheath for Magnet Coils.In 1867 C. E. Varley proposed the use of a copper sheath surrounding amagnet core to diminish self-induction. It has since been used by Brushand others. Sometimes metallic foil is laid between the successive coilsof wire.Synonym--Mutual Induction Protector.Sheath for Transformers.A protective sheath of copper, interposed between the primary andsecondary circuits of an alternating current transformer. It isconnected to the earth. If the primary coil loses its insulation beforeit can leak to the secondary it is grounded. This protects the secondarycircuit from the high electro-motive force of the primary circuit.Shellac.A resin; produced as an exudation upon the branches of certain Asiatictrees, such as the banyan (Ficus religiosa). It is due to punctures inthe bark of the trees in question, which punctures are made by thefemale of the insect coccus ficus or c. lacca.Commercial shellac contains about 90 per cent. of resinous material, therest is made up of wax, gluten, coloring matter and other substances.Shellac is soluble in alcohol, and in aqueous solutions of ammoniumchloride, of borax and in strong ammonia solution. Long standing isrequired in the case of the last named solvent. Dilute hydrochloric andacetic acids dissolve it readily; nitric acid slowly; strong sulphuricacid is without action on it. Alkalies dissolve it.In electric work it is used as an insulator and dielectric. Itsalcoholic solution is used to varnish glass plates of influencemachines, for the coils of induction coils and similar purposes.Resistance in ohms per centimeter cube at 28° C. (82.4 F.)--(Ayrton),9.0E15Specific Inductive Capacity (Wüllner), 2.95 to 3.73The same substance in less pure forms occurs in commerce, as stick lac,lump lac, seed lac, button lac.Shellac Varnish.Solution of shellac in alcohol; methylic alcohol (wood alcohol or woodnaphtha) is often used as solvent.Dr. Muirhead recommends button lac, dissolved in absolute alcohol, andthe top layers decanted. For highest insulation he dissolves the lac inordinary alcohol, precipitates by dropping into water, collects theprecipitate, dries and dissolves in absolute alcohol.Shielded. adj.An electric measuring instrument of the galvanometer type is shieldedwhen it is so constructed that its indications are not seriouslyaffected by the presence of neighboring magnets or by fields of force.Shielding can be effected by using a very strong permanent magnet toproduce a field within which the magnetic needle moves and which reactsupon it, or by enclosing the instrument in a thick iron box.482 STANDARD ELECTRICAL DICTIONARY.S. H. M.Symbol or abbreviation for "simple harmonic motion."Shock, Break.A term in electro-therapeutics; the shock received when an electriccircuit, including the patient in series, is broken or opened.Synonym--Opening Shock.Shock, Electric.The effect upon the animal system of the discharge through it ofelectricity with high potential difference. Pain, nervous shock, violentmuscular contortions accompany it. Of currents, an alternating currentis reputed worse than a direct current; intermediate is the pulsatorycurrent.The voltage is the main element of shock, amperage has also some directinfluence.Shock, Static.A term in electro-therapeutics. The application of static dischargesfrom small condensers or Leyden jars to a patient who is insulated fromthe ground with one electrode applied to the conducting surface on whichhe rests, while the other, a spherical electrode, is brought near thebody so as to produce a disruptive or spark discharge.Short Circuit.A connection between two parts of a circuit, which connection is of lowresistance compared to the intercepted portion. The term is used also asa verb, as "to short circuit a lamp."Fig. 304. DIAGRAM ILLUSTRATING SHORT CIRCUIT WORKING.Short Circuit Working.A method of working intermittently an electro-magnet so as to avoidsparking. It consists in providing a short circuit in parallel with themagnetic coils. This short circuit is of very low resistance. To throwthe magnet into action the short circuit is opened; to throw it out ofaction the short circuit is closed. The shunt or short circuit must beof negligibly small resistance and inductance.483 STANDARD ELECTRICAL DICTIONARY.Shovel Electrodes.Large plate electrodes used in a medical bipolar bath. (See Bath,Bipolar.)Shunt.In a current circuit a connection in parallel with a portion of thecircuit. Thus in a dynamo a special winding for the field may have itsends connected to the bushes, from which the regular external circuitalso starts. The field is then wound in shunt with the armature. In thecase of a galvanometer a resistance coil may be put in parallel with itto prevent too much current going through the galvanometer; thisconnection is a shunt.The word is used as a noun, as "a shunt," or "a connection or apparatusin shunt with another," and as an adjective, as "a shunt connection," oras a verb, as "to shunt a battery."Shunt Box.A resistance box designed for use as a galvanometer shunt. (See Shunt,Galvanometer.) The box contains a series of resistance coils which canbe plugged in or out as required.Shunt, Electro-magnetic.In telegraphy a shunt for the receiving relay consisting of the coils ofan electro-magnet. It is placed in parallel with the relay. Its polesare permanently connected by an armature. Thus it has highself-induction.On opening and closing the circuit by the sending key, extra currentsare produced in the shunt. The connections are so arranged that onmaking the circuit the extra current goes through the relay in the samedirection as the principal current, while on breaking the circuit theinduced current goes in the opposite direction.Thus the extra currents accelerate the production and also the cessationof signalling currents, tending to facilitate the operations of sendingdespatches.Shunt, Galvanometer.A resistance placed in parallel with a galvanometer, so as to shortcircuit its coils and prevent enough current passing through it toinjure it. By knowing the resistance of the shunt and of thegalvanometer coils, the proportion of current affecting the galvanometeris known. This gives the requisite factor for calculation. (SeeMultiplying Power of Shunt.)Shunt Ratio.The coefficient expressing the ratio existing between the current in ashunt and in the apparatus or conductor in parallel with it. (SeeMultiplying Power of/ Shunt.)Shunt Winding.A dynamo or motor is shunt-wound when the field magnet winding is inshunt or in parallel with the winding of the armature.Shuttle Current.A current alternating in direction; an alternating current.484 STANDARD ELECTRICAL DICTIONARY.Side-Flash.A bright flashing lateral discharge from a conductor conveying a currentdue to a static discharge.Sighted Position.In an absolute electrometer (see Electrometer, Absolute) the position ofthe balanced arm carrying the movable disc or plate, when the disc andguard plate are in one plane. The cross-hair on the lever-end is thenseen midway between two stops, or some other equivalent position isreached which is discerned by sighting through a magnifying glass ortelescope.Silver.A metal; one of the elements; symbol Ag.; atomic weight, 108; valency, 1;equivalent, 108; specific gravity, 10.5. It is a conductor of electricity.Relative resistance, annealed, 1.0Specific Resistance, annealed, at 0° C. (32° F.) 1.504 microhms.Resistance of a wire at 0° C. (32° F.), Annealed. Hard Drawn.(a) 1 foot long, weighing 1 grain, .2190 ohms .2389 ohms.(b) 1 foot long, 1/1000 inch thick, 9.048 " 9.826 "(c) 1 meter long, weighing 1 gram, .1527 " .1662 "(d) 1 meter long, 1 millimeter thick, .01916 " .02080 "Resistance annealed of a 1-inch cube, at 0° C. (32°F.) .5921 microhms.Percentage increase in resistance per degree C.(1.8 F.) at about 20° C. (68° F.), annealed, 0.377 per cent.Electro-chemical equivalent, (Hydrogen = .0105) .1134 mgs.Silver Bath.A solution of a salt of silver for deposition in the electroplatingprocess.The following is a typical formula:Water, 10.0 parts by weight.Potassium Cyanide, 5 " "Metallic Silver, 2.5 ""The silver is first dissolved as nitrate and converted into cyanide andadded in that form, or for 2.5 parts metallic silver we may read:Silver cyanide, 3 parts by weight.While many other formulas have been published the above isrepresentative of the majority. Other solvents for the silver thanpotassium cyanide have been suggested, such as sodium hyposulphite, butthe cyanide solution remains the standard.Silver Stripping Bath.Various baths are used to remove silver from old electroplated articles.Their composition depends upon the base on which the metal is deposited.Silvered iron articles are placed as anodes in a solution of 1 partpotassium cyanide in 20 parts of water. As kathode a silver anode or acopper one lightly oiled may be used. From the latter the silver easilyrubs off. For copper articles a mixture of fuming sulphuric acid andnitric acid (40º Beaumé) may be used. The presence of any water in thismixture will bring about the solution of the copper. Or fuming sulphuricacid may be heated to between 300º and 400º F., some pinches of drypulverized potassium nitrate may be thrown in and the articles at oncedipped. These methods effect the solution of the silver, leaving thecopper unattacked.485 STANDARD ELECTRICAL DICTIONARY.Simple Substitution.A method of obtaining a resistance equal to that of a standard. Thestandard is put in circuit with a galvanometer and the deflection isnoted. For the standard another wire is substituted and its lengthaltered until the same deflection is produced. The two resistances arethen evidently identical. The standard can be again substituted toconfirm the result.Sine Curve.If we imagine a point moved back and forth synchronously with apendulum, and if such point made a mark upon paper, it would trace thesame line over and over again. If now the paper were drawn steadilyalong at right angles to the line of motion of the point, then the pointwould trace upon it a line like the profile of a wave. Such line is asine curve. It derives its name from the following construction. Let astraight line be drawn, and laid off in fractions, such as degrees, ofthe perimeter of a circle of given diameter. Then on each division ofthe line let a perpendicular be erected equal in height to the sine ofthe angle of the circle corresponding to that division; then if theextremities of such lines be united by a curve such curve will be a sinecurve.In such a curve the abscissas are proportional to the times, while theordinates are proportional to the sines of angles, which angles arethemselves proportional to the times. The ordinates pass throughpositive and negative values alternately, while the abscissas are alwayspositive.Any number of sine curves can be constructed by varying the diameter ofthe original circle, or by giving to the abscissas a value which is amultiple of the true length of the divisions of circle. If the pendulummethod of construction were used this would be attained by giving agreater or less velocity to the paper as drawn under the pendulum.A species of equation for the curve is given as follows: y = sin( x )In this x really indicates the arc whose length is x, and referenceshould be made to the value of the radius of the circle from which thecurve is described. It will also be noticed that the equation onlycovers the case in which the true divisions of the circle are laid offon the line. If a multiple of such divisions are used, say n times, or1-n times, then the equation should ready = n sin( x ) or y = sin( x ) / nSynonyms--Curve of Sines--Sinusoidal Curve--Harmonic Curve.486 STANDARD ELECTRICAL DICTIONARY.Sine Law.The force acting on a body is directly proportional to the sine of theangle of deflection when--I. The controlling force is constant in magnitude and direction; andII. The deflecting force, although variable in its direction in space,is fixed in direction relatively to the deflecting body.Single Fluid Theory.A theory of electricity. Electricity, as has been said, beingconveniently treated as a fluid or fluids, the single fluid theoryattributes electrical phenomena to the presence or absence of a singlefluid. The fluid repels itself but attracts matter; an excess createspositive, a deficiency, negative electrification; friction, contactaction or other generating cause altering the distribution createspotential difference or electrification. The assumed direction (seeDirection) of the current and of lines of force are based on the singlefluid theory. Like the double fluid theory, q. v., it is merely aconvenience and not the expression of a truth. (See Fluid, Electric, andDouble Fluid Theory.)Synonym--Franklin's Theory.Single Fluid Voltaic Cell.A galvanic couple using only a single fluid, such as the Smee or Voltacell.Simple Harmonic Motion.Motion of a point or body back and forth along a line; the motion of apendulum, as regards its successive swings back and forth, is an exampleof harmonic motion.Sinistrotorsal. adj.The reverse of dextrotorsal, q. v. A helix with left-handed winding, thereverse of an ordinary screw, such as a wood-screw or corkscrew.Skin Effect.A current of very brief duration does not penetrate the mass of aconductor. Alternating currents for this reason are mainly conducted bythe outer layers of a conductor. The above is sometimes called the skineffect.Sled.A contact for electric cars of the conduit system. It is identical withthe plow, q.v., but is drawn after the cars instead of being pushedalong with them.Slide Meter Bridge.A name for a Slide Bridge one meter long. There are also slide halfmeter and slide quarter meter bridges and others. (See Meter Bridge.)S. N. Code.Abbreviation for single needle code, the telegraphic alphabet used withthe single needle system.Soaking-in-and-out.A term for the phenomena of the residual electrostatic charge; thegradual acquirement or loss by a condenser of a portion of itselectrostatic charge.487 STANDARD ELECTRICAL DICTIONARY.Soldering, Electric.(a) Soldering in which the solder is melted by means of electricity;either current incandescence or the voltaic arc may be used. It isidentical in general with electric welding. (See Welding, Electric.)(b) The deposition by electric plating of a metal over the ends of twoconductors held in contact. This secures them as if by soldering. It isused in connecting the carbon filament of an incandescent lamp with theplatinum wires that pass through the glass. Copper is the metal usuallydeposited.Solenoid.The ideal solenoid is a system of circular currents of uniformdirection, equal, parallel, of equal diameter of circle, and with theircenters lying on the same straight line, which line is perpendicular totheir planes.Fig. 305. EXPERIMENTAL SOLENOID.The simple solenoid as constructed of wire, is a helical coil, ofuniform diameter, so as to represent a cylinder. After completing thecoil one end of the wire is bent back and carried through the centre ofthe coil, bringing thus both ends out at the same end. The object ofdoing this is to cause this straight return member to neutralize thelongitudinal component of the helical turns. This it does approximatelyso as to cause the solenoid for its practical action to correspond withthe ideal solenoid.Instead of carrying one end of the wire through the centre of the coilas just described, both ends may be bent back and brought together atthe centre.A solenoid should always have this neutralization of the longitudinalcomponent of the helices provided for; otherwise it is not a truesolenoid.Solenoids are used in experiments to represent magnets and to study andillustrate their laws. When a current goes through them they acquirepolarity, attract iron, develop lines of force and act in general likemagnets.A solenoid is also defined as a coil of insulated wire whose length isnot small as compared with its diameter.488 STANDARD ELECTRICAL DICTIONARY.Sonometer, Hughes'.A sound measurer; a modification of a portion of Hughes' inductionbalance, used for testing the delicacy of the ear or for determining therelative intensity of sounds. (See Hughes' Induction Balance.) It is thearrangement of three coils, two mounted one at each of the ends of agraduated bar, and the third one between them and free to slide back andforth thereon.Sonorescence.The property of producing sounds under the influence of momentary lightradiations rapidly succeeding each other. It is the property utilized inthe photophone, q. v.Fig. 306. MORSE SOUNDER.Sounder.In telegraphy an instrument consisting of an electromagnet with armatureattached to an oscillating bar, the range of whose movements isrestricted by adjusting screws. The armature is drawn away from themagnet by a spring. When a current is sent through the magnet thearmature is drawn towards the poles and produces a sound as the barstrikes a striking piece or second adjusting screw. When the currentceases the bar and armature are drawn back, striking the first mentionedscrew with a distinct sound, the back stroke.The sounder is used to receive Morse and analogous character messages.The forward strokes correspond to the beginnings of the dots or dashesof the code, the back strokes to beginnings of the intervals. Thedistinction between dots and dashes is made by observing the intervalbetween forward and back stroke.Various devices are used to increase the sound. Sometimes a resonancebox is used on which the sounder is mounted.In practice sounders are generally placed on local circuits and areactuated by relays.489 STANDARD ELECTRICAL DICTIONARY.Sound Reading.The art or method of receiving telegraph messages by ear. It is nowuniversally used by all expert Morse operators. It can only be appliedto telegraph systems producing audible sounds; in some cases, as inneedle telegraphy, it may be quite inapplicable.Space, Clearance.The space between faces of the pole pieces and the surface of thearmature in a dynamo. It is really the air gap, but in calculatingdynamo dimensions the thickness of the insulated copper wire windings ofthe commutator are counted in as part of the air gap, because copper isalmost the same as air in impermeability. Clearance space is amechanical factor; the air gap is an electric or magnetic factor.Synonym--Inter-air Space.Space, Crookes' Dark.In an exhausted tube, through which an electric discharge is caused topass, the space surrounding the negative electrode of the tube. Thisspace is free from any luminous effect, and by contrast with the lightof the discharge appears dark. The vacuum may be made so high that thedark space fills the whole space between the electrodes. It is less fora less vacuum and varies for other factors, such as the temperature ofthe negative electrode from which it originates, the kind of residualgas present, and the quality of the spark.Space, Faraday's Dark.The space in an exhausted tube between the luminous glows about the twoelectrodes.Space, Interferric.A term for the air-gap in a magnetic circuit. It is etymologically morecorrect than air-gap, for the latter is often two-thirds or more filledwith the insulating material and copper wire of the armature windings.(See Space, Clearance.)Spark Arrester.A screen of wire netting fitting around the carbons of an arc lamp abovethe globe to prevent the escape of sparks from the carbons.Spark Coil.A coil for producing a spark from a source of comparatively lowelectro-motive force. It consists of insulated wire wound round a coreof soft iron, best a bundle of short pieces of wire. Such a coil may beeight inches long and three inches thick, and made of No. 18-20 copperwire, with a core one inch in diameter. On connecting a batterytherewith and opening or closing the circuit, a spark is produced byself-induction, q. v. It is used for lighting gas.490 STANDARD ELECTRICAL DICTIONARY.Spark, Duration of Electric.Wheatstone determined the duration of the spark given by a Leyden jar as1/24000 second. Feddersen by interposing a tube of water 9 millimeters(.36 inch) long in its path found that it lasted 14/10000 second, andwith one 180 millimeters (7.2 inches) long, 188/10000 second. Lucas andCazin for a 5 millimeter (.2 inch) spark, with different numbers ofLeyden jars, found the following:Number of jars. Duration of Spark.2 .000026 second4 .000041 "6 .000045 "8 .000047 "The duration increases with the striking distance, and is independent ofthe diameter of the balls between which it is produced.Spark Gap.The space left between the ends of an electric resonator (see Resonator,Electric) across which the spark springs. Its size may be adjustable bya screw, something like the arrangement of screw calipers.Sparking.In dynamo-electric machines, the production of sparks at the commutatorbetween the brushes and commutator sections. The sparks are often truevoltaic arcs, and in all cases are injurious if in any quantity, wearingout the commutator and brushes.Sparking, Line or Points of Least.In a dynamo or electric motor the diameter of the commutatordetermining, or the points on the commutator marking the position of thebrushes where the sparking is a minimum. Field magnets powerful inproportion to the armature are a preventative cause. The direction ofthe line fixes the angle of lead to be given to the brushes.Sparking, Resistance to.The resistance to disruptive discharge through its substance offered bya dielectric or insulator. It does not depend on its insulatingqualities, but on its rigidity and strength.Spark, Length of.The length of the spark accompanying the disruptive discharge is countedas the distance from one electrode to the other in a straight line. Itis longer for an increased potential difference between the twoelectrodes. If the gas or air between the electrodes is exhausted thelength increases, until the vacuum becomes too high, when the lengthbegins to decrease, and for a perfect vacuum no spark however small canbe produced. The shape of the conductor which is discharged, thematerial of the electrodes, and the direction of the current are allfactors affecting the length of spark producible.491 STANDARD ELECTRICAL DICTIONARY.Spark Tube.A tube used as a gauge or test to determine when the exhaustion of thevacuum chamber or bulb of an incandescent lamp is sufficiently high.The interior of the tube is connected with the interior of the bulb orchamber of the lamps in process of exhaustion, and hence shares theirdegree of exhaustion. From time to time connections with an inductioncoil are made. When the exhaustion is carried far enough no dischargewill take place through the vacuum. As long as the tube acts like aGeissler tube the exhaustion is not considered perfect.Specific Heat of Electricity.The heat absorbed or given out by a fluid in passing from onetemperature to another depends on its specific heat. In the Peltier andthe Thomson effects. q. v., the electric current acts as the producer ofa change of temperature, either an increase or decrease as the case maybe. This suggests an absorption of and giving out of heat which amountof heat corresponding to a current of known amount is determinable, andmay be referred to any unit of quantity such as the coulomb. This orsome equivalent definite quantity of heat it has been proposed (SirWilliam Thomson) to term the Specific Heat of Electricity.Spent Acid.Acid which has become exhausted. In a battery the acid becomes spentfrom combination with zinc. It also loses its depolarizing power, if itis a chromic acid solution or of that type, and then may be said to bespent.Spent Liquor.The liquor of a plating bath which has become exhausted from use, themetal it contained being all or partly deposited.Sphygmograph, Electric.An electric apparatus for recording the beat of the pulse, both asregards its rate and strength.Sphygmophone.An apparatus for examination of the pulse by the microphone andtelephone.Spiders.Core-discs of a dynamo or motor armature are sometimes perforated with alarge central aperture, are fastened together with insulated bolts, andthe whole mass is secured to the shaft by three- or four-armed spiders.These are like rimless wheels, the ends of their arms being secured tothe hollow cylinder constituting the armature core, and a centralaperture in their hub receiving the shaft.492 STANDARD ELECTRICAL DICTIONARY.Spiral.This term is sometimes used instead of coil, as the primary spiral orsecondary spiral of an induction coil or transformer.Spiral Winding.The winding used on ring armatures. This may diagrammatically berepresented by a spiral carried around the ring shaped core. With twofield poles it gives two collecting points, positive and negative, withfour field poles it gives four collecting points, alternately positiveand negative.Splice Box.A box in which the splices in underground cables and electric lines arecontained. The splicing is generally done in the boxes with the cablesin place. They may be two-way for straight lines, or be four-way for twoside or lateral connections.Spluttering.A term applied to a sound sometimes produced in a voltaic arc, perhapscaused by impure or insufficiently baked electrodes. (Elihu Thomson.)Spring Control.Control of or giving the restitutive force to the needle of agalvanometer, core of a solenoid ammeter or moving part of any similarinstrument by a spring. As an example see Ammeter, Ayrton's.Fig. 307. SPRING JACKS.Spring Jack.An arrangement for effecting, at one insertion of a species of plug, theopening or breaking of a circuit and for the simultaneous connection tothe terminals formed by the breaking of two terminals of another systemor loop. Thus let a line include in its circuit two springs pressingagainst each other, thereby completing the circuit. If a plug or wedgeof insulating material were inserted between the springs so as to pressthem apart it would break the circuit and the whole would constitute aspring jack cut-out. If each side of the plug had a strip of brass orcopper attached to it, and if the ends of another circuit were connectedto these strips, then the insertion of the plug would throw the new lineinto the circuit of the other line.493 STANDARD ELECTRICAL DICTIONARY.Spring Jack Cut-out.A cut-out, of the general construction of a spring jack, q. v., exceptthat a simple insulating plug or wedge is used in place of themetal-faced wedge with its connections of the regular spring jack. Theinsertion of an insulating wedge opens the circuit, which on its removalis closed. The regular spring jack wedge will operate in the same way,if its connections are kept open.Spurious Voltage.The voltage in excess of that developed by a secondary battery which isrequired in the charging process. It is about .25 volt.Square Wire.Wire whose cross-section is a square. It has been used of iron forbuilding up the cores of armatures for dynamos or motors, for which itis peculiarly suitable, and also of copper as a winding for armatures.Staggering. adj.When the brushes of a dynamo are set, one a little in advance of theother on the surface of the commutator, they are said to be setstaggering. It is used to get over a break in the armature circuit.State, Electrotonic.A term expressing an abandoned theory. Faraday at one time proposed thetheory that a wire had to be in the electrotonic state to produceelectro-motive force by movement through an electric field. Any suchidea was ultimately abandoned by Faraday.Static Breeze.The electric breeze obtained by the silent discharge of high tensionelectricity.Static Electricity.Electricity at rest or not in the current form ordinarily speaking. Theterm is not very definite and at any rate only expresses a difference indegree, not in kind. The recognition of the difference in degree has nowto a great extent also disappeared.Station, Central.The building or place in which are placed electrical apparatus, steamengines and plant supplying a district with electric energy.Station, Distant.The place at the further end of a telegraph line, as referred to thehome station.Station, Home.The end of a telegraph line where the operators using the expression areworking.494 STANDARD ELECTRICAL DICTIONARY.Station, Transforming.In alternating current distribution, a building or place where a numberof transformers are worked, so that low potential or secondary circuitsare distributed therefrom.Steel.A compound of iron with carbon. The carbon may range from a fewhundredths of one per cent. up to two per cent. For magnets, tool steeldrawn to a straw color or a little lower is good. All shaping and filingshould be done before magnetization.Steeling.The deposition of iron on copper plates by electrolysis. Inelectrotyping a thin deposit of iron is thus given the relief platesbefore printing from them. The deposit is very hard and exceedinglythin, so that it does not interfere with the perfection of theimpression in the printing process. As the iron becomes worn it can bedissolved off with hydrochloric acid, which does not dissolve thecopper, and a new deposit can be given it. Thus the plate may last foran indefinite number of impressions.The iron bath may be prepared by immersing in a solution of ammoniumchloride, two plates of iron, connected as anode and kathode in acircuit. One plate dissolves while hydrogen is given off from the other.The solution thus produced is used for a bath.The hardness of the deposit, which is really pure iron, gives the nameof "steeling."Synonym--Acierage.St. Elmo's Fire.Luminous static discharge effects sometimes seen on objects elevated inthe air. They are especially noticed on ships' masts. The sailors termthem corpusants (holy bodies). They resemble tongues or globes of fire.Step-by-step Telegraphy.A system of telegraphy in which in the receiving instrument a hand ismade to move step-by-step, with an escape movement around a dial. Foreach step there is a letter and the hand is made to stop at one or theother letter until the message is spelled out. (See Dial Telegraph.)Step-down. adj.A qualification applied to a converter or transformer in the alternatingcurrent distribution, indicating that it lowers potential difference andincreases current from the secondary.Step-up. adj.The reverse of step-down; a qualification of a transformer or converterindicating that it raises the potential and decreases the current in thesecondary.Sticking.The adherence, after the current is cut off, of the armature to thepoles of a magnet. In telegraphy it is a cause of annoyance andobstructs the working. It may, in telegraphy, be due to too weak aspring for drawing back the armature, or to imperfect breaking of thecontact by the despatcher's key or by the receiver's relay.495 STANDARD ELECTRICAL DICTIONARY.Stopping Off.In electroplating the prevention of deposition of the plating metal onany desired portions of the object. It is effected by varnishing theplaces where no coating is desired. An article can be plated withsilver, stopped off in any desired design, and the unvarnished portionsmay then be plated with gold in another bath. Various effects can beproduced by such means.Storage Capacity.A term for the ampere-hours of electricity, which can be taken incurrent form from a storage battery.Storage of Electricity.Properly speaking electricity can only be stored statically or in staticcondensers, such as Leyden jars. The term has been popularly applied tothe charging of secondary or storage batteries, in which there is reallyno such thing as a storage of electricity, but only a decomposition andopposite combination brought about, which leave the battery in acondition to give a current.Storms, Electric.Wide-spread magnetic and electric disturbances, involving thedisturbance of the magnetic elements and other similar phenomena. (SeeMagnetic Storms.)Strain.The condition of a body when subjected to a stress. Various consequencesmay ensue from strain in the way of disturbance of electric and otherqualities of the body strained.Stratification Tube.A Geissler tube, q. v., for showing the stratification of the electricdischarge through a high vacuum.The stratifications are greatly intensified by the presence of a littlevapor of turpentine, alcohol, bisulphide of carbon and other substances.Stray Field.In a dynamo or motor the portion of the field whose lines of force arenot cut by the armature windings.Stray Power.The proportion of the energy wasted in driving a dynamo, lost throughfriction and other hurtful resistances.Streamlets, Current.A conception bearing the same relation to an electric current that linesof force do to a field of force; elementary currents. If evenlydistributed the current is of uniform density; if unevenly distributed,as in alternating currents, the current density varies in differentparts of the cross section of the conductor. This evenness or unevennessmay be referred to the number of streamlets per unit of area ofcross-section.[Transcriber's note: Streamlets per unit of area is redundant withcurrent density.]Stress.Force exercised upon a solid tending to distort it, or to produce astrain.496 STANDARD ELECTRICAL DICTIONARY.Stress, Dielectric.The condition of a dielectric when maintaining a charge; its twoextremities are in opposite states of polarity, or are under permanentpotential difference. As the two opposite polarities tend to unite acondition of stress is implied in the medium which separates them.Stress, Electro-magnetic.The stress produced upon transparent substances in an electro-magneticfield of force. It is shown in the modified optical properties of glassand similar substances placed between the poles of a strongelectro-magnet.Stress, Electrostatic.The stress produced upon substances in an electrostatic field of force;the exact analogue of electro-magnetic stress, and affecting transparentsubstances in the same general way.Striae, Electric.In Geissler tubes the light produced by the electric discharge is filledwith striae, bright bands alternating with dark spaces; these may betermed electric striae.Striking Distance.The distance that separates two conductors charged with electricity ofdifferent potential, when a spark starts between them.Striking Solution.In silver-plating a bath composed of a weak solution of silvercyanide-with a large proportion of free potassium cyanide. It is usedwith a strong current and a large silver anode. This gives aninstantaneous deposition of metallic silver over the surface of thearticle which goes to insure a perfect coating in the silver bathproper. After a few seconds in the striking solution, the article is atonce removed to the plating bath.Stripping.The removal of electroplating from an object. It may be effected inseveral ways. An object whose plating is to be removed is placed in aplating bath of the solution of the metal with which it is coated. It isconnected as the anode to the positive plate of the battery orcorresponding terminal of the generator. A kathode connected to theother terminal being placed in the bath, the coating is dissolved byelectrolytic action. Sometimes simple treatment with acid is employed.Different stripping baths are described under the heads of the differentmetals.S. U.Symbol or abbreviation for Siemens' Unit of Resistance. (See Resistance,Siemens' Unit of.)Sub-branch.A branch or lead of wire taken from a branch lead: a term used inelectric distribution.Sub-main.In electric distribution a conductor connected directly to a main; abranch.497 STANDARD ELECTRICAL DICTIONARY.Subway, Electric.A subterranean system of conduits for electric cables. As generallyconstructed in this country it includes manholes, q. v., at the streetcorners connected by ducts or pipes. These pipes are large enough tohold a cable. To introduce a cable into a duct, which latter may be twoor three inches in diameter, and from two hundred to six or sevenhundred feet long, a wire or rope is first passed through the duct. Thisis done by a set of short wooden rods with screws at the end so as to bescrewed together. Each rod must be shorter than the diameter of themanhole. A rod is thrust in, another is screwed to it and thrust in, andthus a set of rods is made to extend as far as desired. In pulling themout a rope is attached and drawn through. This rope or a larger one isused in drawing the cable through the duct. A windlass is employed todraw the rope with cable attached through the ducts.Sulphating.In storage battery cells, the formation of a hard white basic leadsulphate, Pb2 S05. Its formation is due to over-exhaustion of the cells.As long as the voltage is not allowed to fall below 1.90 volts per celllittle of it forms. As it accumulates it is apt to drop off the plateand fall to the bottom, thus weakening the plate possibly, and deprivingit of active material, and clogging up the cell. If it carries a film ofmetallic lead with it, there is danger of short circuiting the cell.The presence of some sodium sulphate in the solution is said to tend toprevent sulphating, or to diminish it.Sulphur Dioxide.A compound gas, S O2; composed ofSulphur, 32Oxygen, 32Molecular weight, 64Specific gravity, 2.21.It is a dielectric of about the same resistance as air. Its specificinductive capacity at atmospheric pressure is: 1.0037 (Ayrton).Synonyms--Sulphurous Acid--Sulphurous Acid Gas.Sunstroke, Electric.Exposure to the arc light sometimes produces the effects observed incases of sunstroke. It is said that, in the case of workmen at electricfurnaces, these effects are very noticeable. (See Prostration,Electric.)[Transcriber's note: Effects are due to ultraviolet light.]Supersaturated. adj.A liquid is supersaturated when it has dissolved a substance at atemperature favorable to its solubility and its temperature has beenallowed to change, the liquid being kept free from agitation or accessof air, provided crystallization or precipitation has not taken place.It expresses the state of a liquid when it holds in solution more thanthe normal quantity of any substance soluble in it.Surface.A galvanic battery is arranged in surface when all the positive platesare connected together and all the negative plates are also connected.This makes it equivalent to one large cell, the surface of whose plateswould be equal to the aggregate surface of the plates of the battery. Itis also used as an adjective, as "a surface arrangement of battery."498 STANDARD ELECTRICAL DICTIONARY.Surface Density.The relative quantity of an electric charge upon a surface.Surface, Equipotential.A surface over all of which the potential is the same. In a generalsense equipotential surfaces are given by planes or surfaces which cutlines of force at right angles thereto, or which are normal to lines offorce. The conception applies to electrostatic and electro-magneticfields of force, and for current conductors the planes normal to thedirection of the current are equipotential surfaces.The contour of an equipotential surface of a field of force which isdrawn or represented by delineations of its lines of force can beobtained by drawing a line normal thereto. This line will ordinarily bemore or less curved, and will be a locus of identical potentials.An electric equipotential surface may be described as electro-static,electro- magnetic, or magnetic; or may be an equipotential surface of acurrent conductor. Besides these there are mechanical and physicalequipotential surfaces, such as those of gravitation.Surface Leakage.Leakage of current from one part of an insulating material to another bythe film of moisture or dirt on the surface.Suspension.This term is applied to methods of supporting galvanometer needles,balance beams, magnetic compass needles and similar objects which mustbe free to rotate. (See Suspension, Bifilar--Fibre and SpringSuspension--Fibre Suspension--Knife Edge Suspension--PivotSuspension--Suspension, Torsion.)Fig. 308. DIAGRAM OF BIFILAR SUSPENSION.Suspension, Bifilar.Suspension by two vertical parallel fibres, as of a galvanometer needle.The restitution force is gravity, the torsion being comparatively slightand negligible. Leaving torsion out of account the restitution force is(a) proportional to the distance between the threads;. (b) inverselyproportional to their length; (c) proportional to weight of the needleor other object suspended; (d) proportional to the angle ofdisplacement.499 STANDARD ELECTRICAL DICTIONARY.Assume two masses A and B at the end of a weightless rod, suspended bythe parallel cords a A, b B. Let the rod be rotated through an angletheta. Consider the cord a A. Its lower end is swung through the angletheta, as referred to the center O; the cord is deflected from thevertical by an angle psi, such that a A tang(psi)= O A 2 sin (theta/2).The component of gravitation tending to restore A to A, acting towards Ais equal to m g tan(psi). Its moment around O is equal to (m g tan(psi))* (O A cos(theta/2). The whole moment of the couple is 2 m g tan(psi).0 A. cos(theta/2) = 2 m g (O A2/ a A) 2 sin(theta/2). Cos(theta/2) =2mgl(OA2/aA) sin(theta). The moment of the restoring force is thusproportional to the sine of the angle of deflection, and theoscillations of such a system are approximately simple harmonic.(Daniell.)If the twisting is carried so far as to cause the threads to cross andcome in contact with each other the suspension ceases to be a bifilarsuspension, but assumes the nature of a torsional suspension.[Transcriber's note: This is the image of the first paragraph.]Swaging, Electric.Mechanical swaging in which the objects to be swaged are heated by anelectric current as in electric welding.S. W. G.Abbreviation for Standard Wire Gauge.Fig. 309. SIMPLE SWITCH.Switch.A device for opening and closing an electric circuit.A simple type is the ordinary telegrapher's switch. A bar of metal ismounted horizontally by a pivot at one end, so as to be free to rotatethrough an arc of a circle. In one position its free end rests upon astud of metal. One terminal of a circuit is attached to its journal, theother to the stud. Resting on the stud it closes the circuit, in otherpositions it opens the circuit.500 STANDARD ELECTRICAL DICTIONARY.Switch, Automatic.A switch opened and closed by the electric current. It is used forlighting distant incandescent lamps. It includes one or twoelectro-magnets operated by two push buttons. In the usual arrangementone button is black and the other white, for extinguishing and lightingrespectively. When the white button is pushed it causes a current topass through one of the electro-magnets. This attracts its armature,thereby making a contact and throwing the lamps into the lightingcircuit. Then they remain lighted until the black button is pressed.This excites the other magnet, which attracts its armature, breaks thecontact and extinguishes the lights.The object of the automatic switch is to enable distant lamps to belighted without the necessity of carrying the electric leads or wires tothe place whence the lighting is to be done. A very small wire willcarry enough current to operate the magnets, and open circuit batteries,such as Leclanché batteries, may be used as the source of current forthe switch, but generally the lighting current is used for the purpose.A single magnet may do the work. When the lighting button is pressed themagnet is excited, attracts its armature and holds it attracted, untilby pressing the black button the current is turned off from it. In thiscase the lighting current is used to excite the magnet.Switch Board.A board or tablet to which wires are led connecting with cross bars orother switching devices, so as to enable connections among themselves orwith other circuits to be made.Switch, Circuit Changing.A switch whose arm in its swing breaks one contact and swinging overmakes another. It is employed to change the connections of circuits fromone dynamo to another.Synonyms--Changing Switch--Changing Over Switch.Switch, Double Break.A form of switch in which double contact pieces are provided to give abetter contact. One form consists of a hinged bar whose end swings downbetween two pairs of springs. Both pairs are connected to one terminal,and the bar to the other terminal of a circuit.Switch, Double Pole.A heavy switch for central station work, that connects and disconnectstwo leads simultaneously.Switch, Feeder.A heavy switch, often of double contact type, for connecting anddisconnecting feeders from bus bars in central stations.501 STANDARD ELECTRICAL DICTIONARY.Switch, Knife.A switch whose movable arm is a narrow, deep bar of copper or brass, andwhich in making contact is forced in edgeways between two springsconnected to one terminal. The bar is connected to the other terminal.Synonyms--Knife Break Switch--Knife Edge Switch.Switch, Multiple.A switch which in the swing of its bar connects one by one with a numberof contacts so that ultimately the end of its bar is in contact with allat once. It is used to throw lights in and out in succession, and itcan, if the multiple contacts connect with resistances, make themoperate as a rheostat.Switch, Pole Changing.A switch for changing the direction of the current in a circuit.Switch, Reversing.A switch, often of the plug type (see Plug Switch) for changing thedirection of current passing through a galvanometer.Switch, Snap.A switch constructed to give a quick, sharp break. It has a spiralspring interposed between the handle and arm. As the handle is drawnback to open it the spring is first extended, the bar being held by thefriction of the contacts, until the spring suddenly jerks it up, thusbreaking the contact.Switch, Storage Battery Changing.A switch for changing storage battery connections from series tomultiple and back again.Switch, Three Way.A switch, so constructed that by turning its handle connection can bemade from one lead to either of two other leads, and also so thatconnection can be completely cut off.Sympathetic Vibration.The establishment of periodic movement in one body by impulses of thesame period communicated to it from another body in motion. Thus if twotuning forks are of the same pitch and one is sounded the other willbegin to sound by sympathy, the sound waves communicating the necessaryperiodic impulses to it.Sympathetic vibrations are utilized in harmonic telegraphy. (SeeHarmonic Receiver--Telegraph, Harmonic.)