55 STANDARD ELECTRICAL DICTIONARY.B.(a) Abbreviation for Baumé, a hydrometer scale. (See Baumé.) Thus 10º B.means "ten degrees Baumé."(b) Symbol for the coefficient of induced magnetization, or the numberof lines per square centimeter induced in a magnetic circuit or in anyspecified part of it.B. A.Abbreviation for British Association. It is prefixed to standards fixedby the committee of the British Association for the Advancement ofScience. Thus the B. A. ohm means the British Association ohm, a measureof resistance which is equal to the resistance of a column of mercury104.9 centimeters long and one square millimeter area of cross-section.(See Ohm.)Back Induction.A demagnetizing force produced in a dynamo armature when a lead is giventhe brushes. The windings by such setting of the brushes are virtuallydivided into two sets, one a direct magnetizing set, the other a crossmagnetizing set. The latter have a component due to the obliqueness ofthe neutral line, which component is demagnetizing in its action.Back Shock or Stroke of Lightning.A lightning stroke received after the main discharge of the lightning,and caused by a charge induced in neighboring surfaces by the maindischarge. The discharge affects the evenness of distribution ofsurrounding surfaces so that a species of secondary discharge isrequired to make even the distribution, or to supply charge where neededto bind an opposite one. The effects are much lese severe as a rule thanthose of the main charge, although the back stroke has caused death. Theback stroke is sometimes felt a considerable distance from the place ofthe original lightning stroke.Synonym--Return Stroke.Back Stroke.(a) In telegraphy the return stroke of the lever in a telegraph sounder,striking the end of the regulating screw with a sound distinct from thatwhich it produces on the forward stroke as it approaches the magnetpoles. It is an important factor in receiving by ear or sound reading.(b) See Back Shock or Stroke of Lightning.Balance.(a) Wheatstone's Bridge, q. v., is sometimes termed the ElectricBalance.(b) A suspension or torsion balance is one which includes a filament orpair of filaments to whose lower end or ends are attached a horizontalindicator often called a needle, or a magnetic needle. (See TorsionBalance.)(c) See Induction Balance, Hughes'.(d) For Thermic Balance, see Bolometer.(e) See Balance, Ampere.56 STANDARD ELECTRICAL DICTIONARY.Balance, Ampere.A class of electrical measuring instruments due to Sir William Thomsonmay be grouped under this head.The instrument is a true balance or scales such as used for weighing. Itis supported by a torsional wire support in place of knife edges. Ateach end it carries a circle of wire through which the current to betested is passed. The torsional wire support enables the current to becarried to these wire rings. Above and below each of these rings are twosimilar rings, also connected so as to receive the current. They are soconnected that the current shall go through them in opposite senses.When a current passes, therefore, one of these rings repels and oneattracts the balanced ring.The extent of this action measures the intensity of the current. Asliding weight moving along a graduated scale on the balance is used tobring the balance beam into equilibrium when the current is passing. Thedegree of displacement of this weight gives the strength of the currentin amperes.These balances are made for different currents. Thus there is acenti-ampere balance, deka-ampere balance and others, as well as anampere balance.Balata.A gum used as an insulating material. It is the inspissated juice of asapotaceous tree, the bullet tree, Mimusops globosa, of tropicalAmerica, from the Antilles to Guiana. It is intermediate in characterbetween caoutchouc and gutta percha. It is superior to gutta percha insome respects, being very slightly acted on by light.Synonym--Chicle.B. & S.. W. G.Abbreviation for Brown & Sharpe Wire Gauge; the regular American WireGauge. (See Wire Gauge, American.)Barad.An absolute or fundamental unit of pressure, equal to one dyne persquare centimeter.Barometer.An apparatus for measuring the pressure exerted by the atmosphere. Itconsists, in the mercurial form, of a glass tube, over 31 inches long,closed at one end, filled with mercury and inverted, with its open endimmersed in a cistern of mercury. The column falls to a heightproportional to the pressure of the atmosphere from 30 to 31 inches atthe sea level. The "standard barometer" is a height of the mercury or ofthe "barometric column" of 30 inches or 760 centimeters, measured fromthe surface of the mercury in the cistern.The column of mercury is termed the barometric column. Above it in thetube is the Torricellian vacuum.[Transcriber's note: More accurately, 29.92 inches of mercury or 14.696PSI.]Bars of Commutators.The metal segments of a commutator of a dynamo or motor. They are madeof bars of copper, brass or bronze insulated from one another. (SeeCommutator.)Synonyms--Segments, Commutator Segments, Commutator Bars.57 STANDARD ELECTRICAL DICTIONARY.Bath.(a) In electro-plating the solution used for depositing metal ascontained in a vat or tank; as a silver, copper, or nickel bath used forplating articles with silver, copper, or nickel respectively.(b) In electro-therapeutics a bath with suitable arrangements,electrodes and connections for treating patients with electricity. It istermed an electric bath or electro-therapeutic bath.Bath, Bipolar Electric.In electro-therapeutics a bath in which the electrodes are both immersedin the water. The patient placed between them receives part of thedischarge. The electrodes are large copper plates, termed shovelelectrodes.Bath, Electric Shower.An electro-medical shower bath. The patient is placed on a metallicstove or support connected to one of the electric terminals. Waterslightly alkaline is showered upon him. The other electrode is inconnection with the water. The rain of drops and streamlets is theconductor of the current or discharge.Bath, Multipolar Electric.An electro-medical bath with a number of electrodes instead of two.Bath, Stripping.In electro-plating a solution used for dissolving and thus removing theplating from any object. The stripping bath is of the same general typeas the plating bath for the same metal as the one to be dissolved. Theobject to be "stripped" is made the anode of a plating circuit, and asthe current acts the old plating is attacked and dissolves, leaving thebody of the article bare. It is simply the operation of platingreversed. The same term is applied to baths acting by simple solution.Stripping baths are described under the different metals as Silver Bath,Stripping--Gold Bath, Stripping.Bath, Unipolar Electric.An electro-medical bath, in which only one electrode connects with thewater of the bath. The second electrode is supported above the bath. Thepatient touches this while in the water whenever electric action isdesired.FIG. 36. THREE WIRE MOULDING OR BATTEN.FIG. 37. TWO WIRE MOULDING OR BATTEN.58 STANDARD ELECTRICAL DICTIONARY.Batten.A strip of wood grooved longitudinally for holding wires in wiringapartments for electric light or power. In use they are fastened to thewall, grooves inward, or else grooves outward, with the wires lying inthe grooves and covered with the covering strip. For two wire work eachbatten contains two grooves; for the three wire system it contains threegrooves.Synonym--Moulding.Battery.A combination of parts or elements for the production of electricalaction. The term is principally applied to voltaic batteries, but thereare also magnetic batteries, batteries of Leyden jars, and othercombinations, described in their places, which come under this category.[Transcriber's note: A group of similar items such as questions,machines, parts, guns, or electric cells.]Battery, Acetic Acid.A battery whose active solution or excitant is acetic acid or vinegar.This acid has been used by Pulvermacher in his medical battery, as beinga substance found in every household in the form of vinegar. It is nowbut little used.Battery, Alum.A battery using as excitant a solution of alum. This battery has hadsome application for electric clocks, but only to a limited extent.Fig. 38. BALLOON OR FLASK BATTERY.Battery, Aluminum.A battery in which aluminum is the negative plate and aluminum sulphatethe excitant. It is mounted like the gravity battery. Its electro-motiveforce is 0.2 volt.59 STANDARD ELECTRICAL DICTIONARY.Battery, Bagration.A battery with zinc and carbon electrodes immersed in earth sprinkledwith sal ammoniac (ammonium chloride). The copper is preferably firstimmersed in sal ammoniac solution and dried, until a green layer isformed on its surface.The battery is highly praised for its constancy by De la Rive, but maybe regarded as obsolete.Battery, Balloon.A form of gravity battery into whose centre a globular flask, B, isinverted, which is filled before inversion with copper sulphate, ofwhich 2 lbs. are used, and water, so as to remain full. This acts as areservoir of copper sulphate, which it constantly supplies. The glassjar is closed with a perforated wooden cover.Battery, Banked.(a) A battery arranged to feed a number of separate circuits.(b) A battery connected in parallel or in multiple arc.Battery, Bichromate.A battery with amalgamated zinc and carbon plates, with an excitingfluid composed of sulphuric acid, water, and potassium bichromate. Forformula of such solutions see Electropoion Fluid--Kookogey'sSolution--Poggendorff's Solution--Trouvé's Solution--Delaurier'sSolution, and others. (See Index.)Battery, Bunsen.A two fluid porous cell battery. The negative plate is carbon, thepositive plate, amalgamated zinc. The depolarizer is nitric acid orelectropoion fluid, q.v., in which the carbon is immersed. The lastnamed depolarizer or some equivalent chromic acid depolarizing mixtureis now universally used. The excitant is a dilute solution of sulphuricacid. Originally the carbon was made cylindrical in shape and surroundedthe porous cups, in which the zinc was placed. This disposition is nowgenerally reversed. The electro-motive force is 1.9 volts. Thedepolarizing solution is placed in the compartment with the carbon. Theexcitant surrounds the zinc.Fig. 39. BUNSEN'S BATTERY.60 STANDARD ELECTRICAL DICTIONARY.Battery, Cadmium.A battery in which cadmium is the negative plate, sulphate of cadmiumsolution the excitant and depolarizer, and zinc the positive plate.Electro-motive force, .31 volt or about one third of a Daniell cell. Itis mounted like a gravity battery.Battery, Callan.A modification of Grove's battery. Platinized lead is used for thenegative plate, and as a depolarizer a mixture of 4 parts concentratedsulphuric acid, 2 parts of nitric acid, and 2 parts of a saturatedsolution of potassium nitrate. (See Battery, Grove's.)Battery, Camacho's.A battery with carbon negative and amalgamated zinc positive electrodes.The carbon is contained in a porous cup, packed with loose carbon.Electropoion or other fluid of that type serves as excitant anddepolarizer, and is delivered as shown from cell to cell by syphons.Fig. 40. CAMACHO'S BATTERY.Battery, Carré's.A Daniell battery for whose porous cup a vessel or species of sack madeof parchment paper is substituted. The battery has been used forelectric light, and has been run for 200 successive hours, by replacingevery 24 hours part of the zinc sulphate solution by water.61 STANDARD ELECTRICAL DICTIONARY.Battery, Cautery.A battery used for heating a platinum wire or other conductor used forcauterization in electro-therapeutics. The term is descriptive, notgeneric.Battery, Chloric Acid.A battery of the Bunsen type in which an acidulated solution ofpotassium chlorate is used as depolarizer.Battery, Chloride of Lime.A battery in which bleaching powder is the excitant. The zinc electrodeis immersed in a strong solution of salt, the carbon in a porous vesselis surrounded with fragments of carbon and is packed with chloride oflime (bleaching powder). There is no action on open circuit. It has tobe hermetically sealed on account of the odor. Its electro-motive forceis--initial, 1.65 volts; regular, 1.5 volts.Synonym--Niaudet's Battery.Battery, Chromic Acid.Properly a battery in which chromic acid is used as a depolarizer. Itincludes the bichromate battery. (See Battery, Bichromate.)Battery, Closed Circuit.A battery adapted by its construction to maintain a current on a closedcircuit for a long time without sensible polarization. The term ismerely one of degree, for any battery becomes exhausted sooner or later.As examples the Grove, Bunsen or Daniell batteries may be cited.62 STANDARD ELECTRICAL DICTIONARY.Fig. 41. COLUMN BATTERY.Battery, Column.The original Volta's pile. It consists of a series of compound circularplates, the upper or lower half, A, copper; the other, Z, of zinc.Between each pair of plates some flannel or cloth, u, u, is laid, whichis saturated with dilute acid. As shown in the cut, the parts are laidup in two piles, connected at the top with a bar, c, c, and with vesselsof acidulated water, b, b, as electrodes. The great point in setting itup is to be sure that no acid runs from one disc of flannel to the nextover the outside of the plates, as this would create a short circuit.The plates are best compound, being made up of a zinc and a copper platesoldered together. They may, however, be separate, and merely laid oneon the other. In such case great care must be taken to admit no acidbetween them.Volta's pile is no longer used, except occasionally. Trouvé's blottingpaper battery (see Battery, Trouvé's) is a relic of it, and the same isto be said for Zamboni's dry pile.It rapidly polarizes, the flannel retains but little acid, so that it issoon spent, and it is very troublesome to set up. Great care must betaken to have the cloth discs thoroughly saturated, and wrung out toavoid short circuiting by squeezing out of the acid.Battery, D'Arsonval's.A battery of the Bunsen type, differing therefrom in the solutions. Asexcitant in which the zinc electrode is immersed, the following solutionis used:Water, 20 volumes;Sulphuric Acid (purified by shaking with a little olive or similar oil),1 volume;hydrochloric acid, 1 volume.As polarizer in which the carbon is immersed the following is used:Nitric acid, 1 volume;hydrochloric acid, 1 volume;water acidulated with 1/20th sulphuric acid, 2 volumes.Battery, de la Rue.A battery with zinc positive and silver negative electrode; thedepolarizer is silver chloride; the excitant common salt or ammoniumchloride. The cut shows one of its forms of construction.The right hand portion of the cut, Fig. 42, shows the zinc perforated atC for the connection from the next silver plate. The next to it is thenegative electrode of silver around which a mass of silver chloride iscast in cylindrical form. A is a parchment paper cylinder with two holesnear its top, through which the silver wire of the negative electrode isthreaded, as shown in B. A solution of 23 parts ammonium chloride in1,000 parts of water is the approved excitant. Its electro-motive forceis 1.03 volts.The jars are closed with paraffin.Fig. 42. DE LA RUE'S BATTERY.63 STANDARD ELECTRICAL DICTIONARY.Battery, Dry.(a) A form of open circuit battery in which the solutions by a mass ofzinc oxychloride, gypsum, or by a gelatinous mass such as gelatinoussilica, or glue jelly, are made practically solid. Numbers of such havebeen patented, and have met with considerable success.(b) Zamboni's dry pile, q. v., is sometimes termed a dry battery.Battery, Element of.A term applied sometimes to a single plate, sometimes to the pair ofplates, positive and negative, of the single couple.Battery, Faradic.A term applied, not very correctly however, to apparatus for producingmedical faradic currents. It may be an induction coil with battery, or amagneto-generator worked by hand.Battery, Ferric Chloride.A battery of the Bunsen type, in which a solution of perchloride of iron(ferric chloride) is used for the depolarizing agent. A little bromineis added with advantage. The depolarizing agent recuperates on standing,by oxidation from the oxygen of the air.Battery, Fuller's.A battery of the Bunsen type. The zinc plate is short and conical, andrests in the porous jar into which some mercury is poured. An insulatedcopper wire connects with the zinc. A plate of carbon is in the outerjar. The solutions are used as in the Bunsen battery.Synonym--Mercury Bichromate Battery.Battery, Gas.(a) A battery whose action depends on the oxidation of hydrogen as itsgenerating factor. It was invented by Grove. Plates of platinum areimmersed in cups of dilute acid, arranged as if they were plates of zincand carbon, in an ordinary battery. Each plate is surrounded by a glasstube sealed at the top. The plates are filled with acid to the tops.Through the top the connection is made. A current from another batteryis then passed through it, decomposing the water and surrounding theupper part of one set of plates with an atmosphere of oxygen and of theother with hydrogen. Considerable quantities of these gasses are alsooccluded by the plates. On now connecting the terminals of the battery,it gives a current in the reverse direction of that of the chargingcurrent.This battery, which is experimental only, is interesting as being thefirst of the storage batteries.(b) Upward's Chlorine Battery and any battery of that type (see Battery,Upward's,) is sometimes termed a gas battery.64 STANDARD ELECTRICAL DICTIONARY.Battery Gauge.A pocket or portable galvanometer for use in testing batteries andconnections.Battery, Gravity.A battery of the Daniell type, in which the porous cup is suppressed andthe separation of the fluids is secured by their difference in specificgravity. A great many forms have been devised, varying only in details.The copper plate, which is sometimes disc shaped, but in any case ofinconsiderable height, rests at the bottom of the jar. Near the top thezinc plate, also flat or of slight depth, is supported. As excitingliquid a strong solution of copper sulphate lies at the bottom of thejar. This is overlaid by a solution of zinc sulphate, or sodiumsulphate, which must be of considerably less specific gravity than thatof the copper sulphate solution. In charging the jar one-tenth of asaturated solution of zinc sulphate mixed with water is sometimes usedas the upper fluid. This may be first added so as to half fill the jar.The strong solution of copper sulphate may then be added with a syphonor syringe underneath the other so as to raise it up. From time to timecopper sulphate in crystals are dropped into the jar. They sink to thebottom and maintain the copper sulphate solution in a state ofsaturation.Fig. 43. GRAVITY BATTERY OF THE TROUVÉ-CALLAUD TYPE.If the battery is left on open circuit the liquids diffuse, and metalliccopper precipitates upon the zincs. This impairs its efficiency andcreates local action. As long as the battery is kept at work on closedcircuit work but little deposition, comparatively speaking, occurs.From time to time, in any case, the zinc plates are removed and scraped,so as to remove the copper which inevitably forms on their surface. Caremust be taken that the zinc sulphate solution, which is constantlyincreasing in strength, does not get so strong as to become of as highspecific gravity as the copper sulphate solution. From time to time someof the upper solution is therefore removed with a syphon or syringe andreplaced with water. An areometer is useful in running this battery.65 STANDARD ELECTRICAL DICTIONARY.Battery, Grenet.A plunge battery with zinc positive and carbon negative electrodes.Electropoion or other chromic acid or bichromate solution is used asdepolarizer and excitant. The zinc plate alone is plunged into andwithdrawn from the solution.Fig. 44. GRENET'S BATTERY.Fig. 45. GROVE'S BATTERY.Battery, Grove's.A two fluid galvanic battery. A porous cup has within it a riband ofplatinum, which is the negative plate; amalgamated zinc in the outer jaris the positive plate. Dilute sulphuric acid (10 per cent. solution) isplaced in the outer jar, and strong nitric acid (40° B.) as adepolarizer in the porous cups. Its E. M. F. is 1.96 volts.It is objectionable, as it gives off corrosive nitrous fumes. These areproduced by the oxidation of the nascent hydrogen by the nitric acid, bythe following reaction:3 H + H N O3 = 2 H2 O + N O. There are other reactions, one of whichresults in the formation of ammonia by the reduction of the nitric acidradical by the hydrogen. Ammonium can be detected in the spent liquids.66 STANDARD ELECTRICAL DICTIONARY.Battery, Hydrochloric Acid.A battery in which hydrochloric acid is used as the excitant. Manyattempts have been made to use this acid in batteries, but the volatilenature of the acid causes the production of so much odor with corrosivefumes that it has never come into use.Battery, Lead Chloride.A battery of the lead sulphate type in which lead chloride is thedepolarizer. It has had no extended use.Battery, Lead Sulphate.A battery similar to Marié Davy's battery or the gravity battery, butusing lead sulphate as depolarizer and excitant. Lead, copper or tin isthe material of the negative plate. Becquerel used the lead sulphate asa solid cylindrical mass surrounding a lead rod 1/5 to 1/4 inch indiameter. One part of common salt may be mixed with 5 parts of the leadsulphate. The electro-motive force is about 0.5 volt. The resistance isvery high.Battery, Leclanché.An open circuit battery with porous cup. In the outer jar is a zinc rod;a carbon plate is placed in the porous cup. The latter is packed with amixture of clean powdered manganese binoxide as depolarizer, andgraphite in equal volumes. A strong solution of ammonium chloride (salammoniac) is placed in the outer jar. It is only used on open circuitwork. Its electromotive force is 1.48 volts, when not polarized.The reaction is supposed to be about the following:2 N H4 Cl + 2 Mn O2 + Zn = Zn Cl2 + 2 N H3 + H2 0 + M2 O3The battery rapidly weakens on open circuit, but quickly recuperates.There is another form of this battery, termed the agglomerate battery.(See Battery, Leclanché Agglomerate.)Fig. 46. LECLANCHÉ BATTERY.Battery, Leclanché Agglomerate.A form of the Leclanché in which the porous jar is suppressed. Cakesmade of a mixture of carbon, 52 parts; manganese binoxide, 40 parts; gumlac, 5 parts; potassium bisulphate, 3 parts, compressed at 300atmospheres, at a temperature of 100° C. (212° F.), are fastened byIndia rubber bands or otherwise against the carbon plate. Theseconstitute the depolarizer. Various shapes are given the carbon anddepolarizing agglomerates.Battery, Local.A battery supplying a local circuit (see Circuit. Local). The current isgoverned by the relay situated on the main line and operated by itscurrent.Battery, Main.The battery used in operating the main line. It is usually applied totelegraphy. Its function is then to supply current for working relays,which in turn actuate the local circuits.Main and local circuits and batteries are also used in the automaticblock system of railroad signalling.67 STANDARD ELECTRICAL DICTIONARY.Battery, Marié Davy's.A two fluid porous cup battery with carbon negative plate, zinc positiveplate, and mercury sulphate, a nearly insoluble salt, as depolarizer andexcitant. Mercurous or mercuric sulphates have been used in it. Itselectromotive force is 1.5 volts. The local action and waste, owing tothe slight solubility of the mercury compounds, is very slight. If usedon close circuit it becomes polarized. It is also subject under extremecircumstances to reversal of polarity, zinc becoming deposited upon thecarbon, and there forming a positive electrode.In using the cells in series the level of liquid in all must be thesame, otherwise the cell in which it is lowest will become polarized andexhausted.Modifications of this battery on the lines of the gravity battery havebeen constructed.Synonym--Sulphate of Mercury Battery.Battery, Maynooth's.A battery of the Bunsen type, with cast iron negative plate. The irontakes the passive form and is not attacked.Battery, Medical.A term applied very indiscriminately to medical current generators, andto medical induction coils, or to any source of electricity, static orcurrent, for medical application.68 STANDARD ELECTRICAL DICTIONARY.Battery, Meidinger's.A variety of Daniell cell of the gravity type. The plates arecylindrical. The zinc plate lies against the upper walls of the vessel.The copper plate of smaller diameter rests on the bottom. A large tube,with an aperture in its bottom, is supported in the centre and ischarged with copper sulphate crystals. The cup is filled with a dilutesolution of Epsom salts (magnesium sulphate) or with dilute sulphuricacid.Battery Mud.A deposit of mud-like character which forms in gravity batteries andwhich consists of metallic copper precipitated by the zinc. It indicateswasteful action.Battery, Multiple-connected.A battery connected in parallel, all the positive plates being connectedto one electrode, and all the negative to another.Battery, Nitric Acid.A battery in which nitric acid is used as the excitant. Owing to itscost and volatility this acid has been but little used in batteries,other than as a depolarizer. In Grove's battery (see Battery, Grove's)it has been thus used.Battery of Dynamos.A number of dynamos may be arranged to supply the same circuit. They arethen sometimes termed as above, a Dynamo Battery. They may be arrangedin series or in parallel or otherwise combined.Battery of Leyden Jars.To produce the quantity effect of a single large Leyden jar with anumber of small ones they are often connected in parallel and termed abattery. In such case the inner coatings are all connected by regularbar conductors, and the outside coatings are also all in connection.They are conveniently placed in a box or deep tray whose inner surfaceis lined with tinfoil, with an outside connection for grounding, etc.The cascade, q. v., arrangement is not so generally termed a battery.Battery, Open Circuit.A battery adapted for use in open circuit work. Its main requirement isthat it shall not run down, or exhaust itself when left on open circuit.The Leclanché battery is very extensively used for this work. Its actionis typical of that of most open circuit batteries. It is without anyaction on open circuit. It is very quickly exhausted on closed circuit,but recuperates or depolarizes quite soon when on open circuit. It isalways in condition for a momentary connection, but useless for steadywork.Battery, Oxide of Copper.A battery with zinc positive and iron negative electrodes. The excitantis a 30 or 40 per cent. solution of sodium or potassium hydrate (causticsoda or caustic potash). The depolarizer is copper oxide. In action thecopper is gradually reduced to the metallic state. The iron element isoften the containing vessel. The battery is practically inactive on opencircuit.Its electro-motive force varies from .75 to .90 volt. To prevent theformation of sodium or potassium carbonate the cell should be closed, orelse the liquid should be covered with mineral oil.Synonyms--Lalande & Chaperon Battery--Lalande-Edison Battery.69 STANDARD ELECTRICAL DICTIONARY.Battery, Peroxide of Lead.A battery in which peroxide of lead (lead binoxide) is the depolarizer.It is a sort of predecessor of the present secondary battery.Battery, Platinized Carbon.A modification of Smee's battery, in which platinized carbon is used forthe negative plates. Before polarization the E. M. F. is equal to thatof Smee's battery. Polarization reduces its electro-motive forceone-half.Battery, Plunge.A battery whose plates are mounted so as to be immersed in the batterycups or cells, when the battery is to be used, and withdrawn andsupported out of the cups when not in use. The object is to preventwasting of the plates by standing in the solution. It is a constructiongenerally used with sulphuric acid--chromic acid solution andamalgamated zinc and carbon plates.Battery, Pneumatic.A battery arranged to have air blown through the solution to assistdiffusion and depolarization. It is a construction applied to chromicacid or bichromate batteries.Battery, Primary.A battery in which the current is supplied by the solution of one of theplates by the solution. The term distinguishes it from a secondary orstorage battery.Battery, Pulvermacher's Electro-Medical.In this battery, the electrodes were zinc and copper wires wound uponsmall pieces of wood. Dilute vinegar was used as the excitant, becauseit could be found in every household. Formerly the battery had greatsuccess. It is now little used.Battery, Sal Ammoniac.Batteries in which a solution of ammonium chloride is the excitant; theyare very extensively used on open circuit work. (See Battery,Leclanché.)The crystals formed in these batteries have been analyzed and found toconsist of ammonium zinc chloride, 3 Zn Cl2, 8 N H3, 4 H20.Battery, Salt, or Sea Salt.Batteries in which a solution of sodium chloride or common salt is theexcitant, have been largely used, especially for telegraphic purposes.The Swiss telegraphs use a carbon-zinc combination with salt and wateras the excitant. The batteries are sometimes mounted as plungebatteries. They are exhausted by short circuiting after some hours, butrecuperate on standing. The zinc is not amalgamated.70 STANDARD ELECTRICAL DICTIONARY.Battery, Sand.A battery whose cells are charged with sand saturated with dilute acid.It prevents spilling of acid. It is now practically obsolete.Fig. 47. SECONDARY BATTERY.Battery, Secondary.A voltaic battery whose positive and negative electrodes are formed ordeposited by a current from a separate source of electricity byelectrolysis. On disconnection the battery is ready to yield a current,in the reverse direction of that of the charging current. The usual typehas lead plates on one of which lead binoxide and on the other of whichspongy lead is formed. The lead binoxide seems to be the negativeelement, and it also acts as the depolarizer. The spongy lead is thepositive electrode. The solution is dilute sulphuric acid of specificgravity 1.17. The action consists first in the oxidation of the spongylead. The hydrogen set free by the reaction, and which by electrolytictransfer goes to the other plate, reduces the lead binoxide toprotoxide. The sulphuric acid then attacks the oxides and converts theoxides into sulphates.The charging process consists in sending a current in the reversedirection through the battery. If there are several cells they arearranged in series, so that each one receives the same intensity ofcurrent. An electrolytic decomposition takes place, the lead sulphate onone plate is reduced to metallic lead, and that on the other plate isoxidized to lead binoxide. It is then ready for use.71 STANDARD ELECTRICAL DICTIONARY.The plates in a lead plate battery are of very large area per cell, andare placed close together. Sometimes, as in Planté's battery, large flatplates are laid together with a separating insulator between them, andare then rolled into a spiral. Sometimes, the most usual arrangement,the plates are in sets, the positive and negative ones alternating, andeach cell containing a number of plates.To secure a good quantity of active material, the plates are sometimesperforated, and the perforations are filled with oxide of lead. Thisgives a good depth of material for the charging current to act on, andavoids the necessity for a tedious "forming," q. v.The electro-motive force of such a battery per cell is 2 volts. Itsresistance may only be one or two-hundredths of an ohm. An intensecurrent of many amperes can be supplied by it, but to avoid injuring thecell a current far less than the maximum is taken from it.To charge it, a slightly greater electro-motive force, the excess beingtermed spurious voltage, is required.Fig. 48. SIEMENS' AND HALSKE'S PAPER PULP BATTERY.72 STANDARD ELECTRICAL DICTIONARY.Battery, Secondary, Plante's.Plante's secondary battery is one of the earlier forms of storagebattery, but has had much success. Two lead plates, large in area andclose together but not touching, are "formed," by exposure to anelectrolyzing current of electricity in one direction, while they areimmersed in dilute sulphuric acid. This converts the surface of oneplate into binoxide. The cell is then allowed to discharge itself almostcompletely, when the charging current is again turned on. This processis repeated over and over again, until the surfaces of the plates areconsiderably attacked, one plate, however, being maintained in a stateof oxidation. After a few days of this operation a period of rest isallowed between the reversals, which sets up a local action on theoxidized plate, between the metallic lead of the plate, and its coatingof binoxide. This causes the lead to be attacked, under the influence ofthe local couple, and sulphate of lead is formed, which, ultimately, bythe charging current is converted into peroxide. These operationsproduce an exceedingly good battery. The process described is termedforming.The plates separated by strips of insulating material are generallywound into a double spiral.Battery, Siemens' and Halske's.A Daniell battery of peculiar shape. The copper, C, is at the bottom ofthe glass jar, A. The inner jar, K, has the form of a bell, and supportsa mass of paper pulp, which is dampened with sulphuric acid. The zinc,Z, rests on top of the mass of pulp. The battery is very durable, but ofhigh resistance.Battery, Sir William Thomson's.A form of Daniell battery, of the gravity type. The receptacles areshallow wooden trays lined with lead. A thin plate of copper rests onthe bottom. The zinc plate is of gridiron shape, and rests on woodenblocks which support it in a horizontal position above the copper. Onetray is placed on top of the other, the upper tray resting on thecorners of the zinc plate which rise above the level of the top of theflat vessel. Thus connection is assured without wires or binding posts.It is charged like a gravity battery. The density of the zinc sulphatesolution should be between 1.10 and 1.30. The circuit must be keptclosed to prevent deposition of metallic copper on the zinc. The entiredisposition of the battery is designed to reduce resistance.Battery, Skrivanow.A pocket battery of the De la Rue type, with a solution of 75 partscaustic potash in 100 parts of water as the excitant. The silverchloride is contained in a parchment paper receptacle. Itselectro-motive force is 1.45 to 1.5 volts.Battery, Smee's.A single fluid combination, with zinc positive plate, and a plate ofsilver, coated with platinum black, for the negative plate. The finelydivided platinum affords a surface from which the hydrogen bubblesinstantly detach themselves, thus preventing polarization. The liquid isa mixture of one part sulphuric acid to seven parts of water. For thenegative plate silver-plated copper, coated with platinum black, isused. Electromotive force, .47 volt.Fig. 49. SMEE'S BATTERY.73 STANDARD ELECTRICAL DICTIONARY.Fig. 50. SPIRAL BATTERY, OR HARE'S DEFLAGRATOR.Battery, Spiral.A battery whose plates of thin zinc and copper are wound into a spiralso as to be very close, but not touching. Dilute sulphuric acid is theexcitant. It is now practically obsolete.Synonyms--Calorimeter--Hare's Deflagrator.Battery, Split.A battery of a number of voltaic cells, connected in series, with theircentral portion grounded or connected to earth. This gives the ends ofopposite potentials from the earth, and of difference therefrom equal tothe product of one-half of the number of cells employed, multiplied bytheir individual voltage.Battery Solutions, Chromic Acid.A number of formulae have been proposed for these solutions. (SeeElectropoion Fluid--Kookogey's Solution--Poggendorff's Solution--Trouvé's Solution--Delaurier's Solution--Chutaux's Solution--Dronier'sSalt--Tissandier's Solution.)Battery, Trough.A battery whose elements are contained in a trough, which is divided bycross-partitions so as to represent cups. A favorite wood for the troughis teak, which is divided by glass or slate partitions. Marine glue orother form of cement is used to make the joints tight. For porous cupdivisions plates of porous porcelain or pottery are placed across,alternating with the impervious slate partitions.Battery, Trouvé's Blotting Paper.A battery of the Daniell type in which the solutions are retained byblotting paper. A considerable thickness of blotting paper lies betweenthe two plates. The upper half of the thickness of the blotting paper issaturated with a solution of zinc sulphate, on which the zinc platerests.The lower half of the paper is saturated with copper sulphate solution,and this rests upon the copper plate.Fig. 51. TROUVÉ'S BLOTTING PAPER BATTERY.74 STANDARD ELECTRICAL DICTIONARY.Battery, Tyer's.A modification, as regards the positive element, of Smee's battery, q.v. The bottom of the battery jar contains a quantity of mercury in whichpieces of zinc are thrown, and this constitutes the positive element.A ball of zinc at the end of an insulated copper wire affords theconnection with the zinc and mercury. Its great advantage is that thesmallest scraps of zinc can be used in it, by being dropped into themercury. The negative plate is platinized silver; the exciting liquid,dilute sulphuric acid.Fig. 52. TYER'S BATTERY.75 STANDARD ELECTRICAL DICTIONARY.Fig. 53. SECTION OF UPWARD'S BATTERY.Fig. 54. ELEVATION OF UPWARD'S BATTERY.Battery, Upward's.A primary voltaic cell, the invention of A. Renée Upward. Referring tothe cuts, the positive plate. Z, is of cast zinc; it is immersed inwater, in a porous cup, B. Outside of the porous cup and contained inthe battery jar are two carbon plates, C, C, connected together. Therest of the space between the porous cup and battery jar is packed withcrushed carbon, and the top is cemented. Chlorine gas is led by a pipe,D, into the outer cell. It diffuses through the fine carbon, dissolvesin the water, and so finds its way to the zinc, which it attacks,directly combining therewith, and forming zinc chloride (Zn + 2 Cl = ZnCl 2). Such of the chlorine as is not absorbed finds its way by an outlettube, E, to the next cell. Arrangements are provided for generatingchlorine gas as required. The high specific gravity of the gas isutilized in regulating its distribution through the cells. Theelectro-motive force of the cell is 2.1 volts. A cell 11.5 by 5.5 inchesand 12.5 inches deep has a resistance of 0.2 ohm.An overflow pipe, F, with faucet, T, is supplied to withdraw thesolution of zinc chloride as it accumulates.76 STANDARD ELECTRICAL DICTIONARY.Battery, Varley's.A Daniell battery of the Siemens' and Halske's type (see Battery,Siemens' and Halske's), in which zinc oxide is substituted for the paperpulp of the other battery. It has been very little used.Battery, Volta's.The original acid battery. It has a negative electrode of copper, apositive electrode of zinc; the excitant is sulphuric acid diluted withsixteen times its volume of water. It rapidly polarizes, and is verylittle used.Battery, Voltaic or Galvanic.An apparatus for converting chemical energy directly into electricenergy. This is as broad a definition as can well be given. The generalconception of a battery includes the action of electrolysis, a solutionin the battery acting upon one of two conducting electrodes immersed insuch fluid, which dissolves one of them only, or one more than theother. The best way to obtain a fundamental idea of a battery is tostart with the simplest. Dilute sulphuric acid dissolves neither purezinc nor copper. But it has a far stronger affinity for the first namedmetal. If now we immerse in dilute acid two plates, one of pure zinc,and one of copper, no action will be discernible. But if the plates arebrought in contact with each other a stream of bubbles of hydrogen gaswill escape from the surface of the copper and the zinc will dissolve.By applying proper tests and deductions it will be found that the copperand zinc are being constantly charged with opposite electricities, andthat these are constantly recombining. This recombination produces whatis known as an electric current.To constitute a battery the zinc and copper plates must be connectedoutside of the solution. This connection need not be immediate. Anyconductor which touches both plates will bring about the action, and thecurrent will pass through it.The easiest way to picture the action of a battery is to accept thedoctrine of contact action. In the battery the molecules of water arepulled apart. The hydrogen molecules go to the copper, the oxygenmolecules go to the zinc, each one, leaving its contact with the other,comes off charged with opposite electricity. This charges the plates,and the continuous supply of charge and its continuous dischargeestablishes the current.The accumulation of hydrogen acts to stop the action by polarization.Its own affinity for oxygen acts against or in opposition to theaffinity of the zinc for the same element, and so cuts down the action.A depolarizer of some kind is used in acid batteries for this reason. Assuch depolarizer has only to act upon one plate, in most batteries it isusual to surround such plate only, as far as it is possible, with thedepolarizer. The solution which dissolves the zinc is termed theexcitant or exciting solution.To this concrete notion of a voltaic battery the different modificationsdescribed here may be referred. Zinc, it will be seen, forms the almostuniversally used dissolved plate; carbon or copper forms the most usualundissolved plate; sulphuric acid in one form or another is the mostusual excitant.The solution in a voltaic battery is electrolyzed (see Electrolysis).Hence the solutions must be electrolytes. The sulphuric acid and otheringredients play a secondary role as imparting to the battery fluidsthis characteristic.It is not necessary to have electrodes of different substances, the samemetal maybe used for both if they are immersed in different solutionswhich act differentially upon them, or which act with more energy on onethan on the other. Such are only of theoretical interest.77 STANDARD ELECTRICAL DICTIONARY.Battery, Water.A voltaic battery, whose exciting fluid is water. They are used forcharging quadrant electrometer needles and similar purposes. Theypolarize very quickly and are of high resistance. Hence very smallplates in large number can be used without impairing their advantage.Rowland's water battery dispenses with cups and uses capillarityinstead. The zinc and platinum or copper plates of a couple are placedvery close together, while the couples are more distant. On dipping intowater each couple picks up and retains by capillarity a little waterbetween its plates, which forms the exciting fluid. Many hundred couplescan be mounted on a board, and the whole is charged by dipping intowater and at once removing therefrom. It then develops its fullpotential difference.Fig. 55. SECTION OF WOLLASTON BATTERY.Fig. 56. PLATES OF WOLLASTON'S BATTERY.78 STANDARD ELECTRICAL DICTIONARY.Battery, Wollaston.The original plunge battery is attributed to Wollaston. He also inventedthe battery known by his name, having the disposition shown in the cut,of zinc Z, surrounded by a thin sheet of copper C; o, o', o", are theterminals and B, B, the battery jars. Dilute sulphuric acid is used forexciting fluid.B. A. U.Abbreviation for British Association unit, referring generally to the B.A. unit of resistance.B. A. Unit of Resistance.The original ohm used under that name previous to 1884. The Pariscommittee of that year recommended as a practical unit what is known asthe legal ohm. (See Ohm, Legal.)1 Legal Ohm = 1.0112 B. A. Units of Resistance.1 B. A. Unit of Resistance = .9889 Legal Ohms.1 B. A. Unit of Resistance = .98651E9 C. G. S. units.B. E. adj.British Engineering, a qualification of a set of units, the B. E. units,having for base the foot and pound. The term is but little used.Beaumé Hydrometer.A hydrometer graduated on the following principle:The zero point corresponds to the specific gravity of water for liquidsheavier than water. A solution of 15 parts of salt in 85 parts of watercorresponds in specific gravity to 15° B., and between that and zerofifteen equal degrees are laid out. The degrees are carried down belowthis point.The zero points for liquids lighter than water correspond to thespecific gravity of a solution of 10 parts of salt in 90 parts of water.The specific gravity of water is taken as 10° B. This gives ten degreeswhich are continued up the scale.Becquerel's Laws of Thermoelectricity.These are stated under the heads, Law of Intermediate Metals and Law ofSuccessive Temperatures, q. v.Bed Piece.In a dynamo or motor the frame carrying it, including often thestandards in which the armature shaft is journaled, and often the yokeor even entire field magnet core.Bell, Automatic Electric.A bell which rings as long as the circuit is closed, having a circuitbreaker operated by its own motion. (See Bell, Electric.)Synonyms--Trembling Bell--Vibrating Bell.Bell, Call.A bell operated by electricity, designed to call attention, as to atelephone or telegraphic receiver. (See Bell, Electric.)79 STANDARD ELECTRICAL DICTIONARY.Bell Call.A calling device for attracting the attention of any one, consisting ofsome type of electric bell.Bell, Circular.A gong-shaped bell, whose clapper and general mechanism is within itscavity or behind it.Bell, Differentially Wound.An electric bell, whose magnet is wound differentially so as to preventsparking.Fig. 57. AUTOMATIC ELECTRIC BELL.Bell, Electric.A bell rung by electricity. Generally it is worked by a current excitingan electro-magnet, attracting or releasing an armature which is attachedto the vibrating or pivoted tongue of the bell. It may be worked by adistant switch or press-button, q. v., ringing once for each movement ofthe distant switch, etc., or it may be of the vibrating bell type asshown in the cut. When the current is turned on in this case it attractsthe armature. As this moves towards the poles of the magnet it breaksthe circuit by drawing the contact spring, q. v., away from the contactpoint, q. v. This opens the circuit, to whose continuity the contact ofthese two parts is essential. The hammer, however, by its momentumstrikes the bell and at once springs back. This again makes the contactand the hammer is reattracted. This action continues as long as thecircuit is closed at any distant point to which it may be carried. Theordinary vibrating bell is a typical automatic circuit breaker, q. v.,this type keeping up the ringing as long as the circuit is closed. Otherbells have no electric contact and simply ring once every time thecircuit is closed. Others worked by an alternating current ring once foreach change of direction of current.80 STANDARD ELECTRICAL DICTIONARY.Bell, Electro-mechanical.A bell which has its striking train operated by a spring or descendingweight, and which train is thrown into action by the release of a detentor equivalent action by the closing of an electric circuit. It rings forany given time after being started.Bell, Indicating.A bell which by drop-shutter or other indicator connected in circuitwith it, indicates its number or other designation of its call.Bell, Magneto.An electric bell operated by the alternating current from a magnetogenerator. It has a polarized armature and no circuit breaker. Thearmature is attracted first in one direction and then in the other, asthe current alternates and reverses the polarity of the electro-magnet.Bell, Relay.A bell operated by a relay circuit.Bias.In polarized relay the adjustment of the tongue to lie normally againstone or the other contact. (See Relay, Polarized.)81 STANDARD ELECTRICAL DICTIONARY.Fig. 58. RESISTANCE COILS SHOWING BIFILAR WINDING.Bifilar Winding.The method followed in winding resistance coils to prevent them fromcreating fields of force. The wire is doubled, and the doubled wirestarting with the bend or bight is wound into a coil. The current goingin opposite senses in the two lays of the winding produces no field offorce.Binary Compound.A chemical compound whose molecule contains only two elements, such aswater (H2 0), lead oxide (Pb 0), and many others.Binding.In a dynamo or motor armature the wire wound around the coils to securethem in place and prevent their disturbance by centrifugal action.Fig. 59. DOUBLE BINDING POST.Fig. 60. BINDING POST, ENGLISH PATTERN.FIG. 61. WOOD SCREW BINDING POST.Binding Posts or Screws.Arrangements for receiving the loose end of a wire of an electriccircuit, and securing such end by a screw. Several constructions areused, as shown here. Sometimes the wire is passed through a hole, and ascrew tapped in at right angles to the hole is screwed down upon thewire. Sometimes the wire is clamped between two shoulders, one on thescrew, the other on the post. The screw is often a flat-headed thumbscrew or has a milled edge. Sometimes the screw has a slot and is turnedby a screw-driver.Several openings are often provided in the same post for differentwires.Binnacle.The case containing a mariner's compass on shipboard. It is enclosedcompletely; it has a glass side or window through which the compass canbe seen, and is provided with one or two lamps arranged to light thecard, while showing as little light as possible outside.82 STANDARD ELECTRICAL DICTIONARY.Bioscopy, Electric.The diagnosis of life and death by the action of the animal system whensubjected to an electric current or electrification.Bismuth.A metal, one of the elements, atomic weight, 210 ; equivalent, 70;valency, 3; specific gravity, 9.9. It is a conductor of electricity.Relative Resistance, compressed, (silver = 1) 87.23Specific Resistance, 131.2 microhmsResistance of a wire(a) 1 foot long, weighing 1 grain, 18.44 ohms(b) 1 foot long, 1/1000 inch thick, 789.3 "(c) 1 meter long, weighing 1 gram, 12.88 "(d) 1 meter long, 1 millimeter thick, 1.670 "Resistance of a 1-inch cube 51.65 microhmsElectro chemical equivalent, .7350 (Hydrogen = .0105)(See Thermo-electric Series.)Figs. 62, 63. INCANDESCENT WIRE FUSE. ABEL'S PATENT.Fig. 64. VON EBNER'S FRICTIONAL ELECTRIC MACHINE FOREXPLODING ELECTRIC FUSES OR DETONATORS.Bi-telephone.A pair of telephones arranged with a curved connecting arm or spring, sothat they can be simultaneously applied to both ears. They areself-retaining, staying in position without the use of the hands.83 STANDARD ELECTRICAL DICTIONARY.Blasting, Electric.The ignition of blasting charges of powder or high explosives by theelectric spark, or by the ignition to incandescence (red or white heat)of a thin wire immersed in or surrounded by powder. Special influence orfrictional electric machines or induction coils are used to producesparks, if that method of ignition is employed. For the incandescentwire a hand magneto is very generally employed. (See Fuse, Electric.)The cuts, Figs. 62 and 63, show one form of incandescent wire fuse. Thelarge wires are secured to the capsule, so that no strand can come uponthe small wire within the cavity.The cut, Fig. 64, shows a frictional electric machine for igniting sparkfuses.Bleaching, Electric.Bleaching by agents produced or made available by the direct action ofelectricity. Thus if a current under proper conditions is sent through asolution of common salt (sodium chloride), the electrodes being closetogether, the salt is decomposed, chlorine going to one pole and sodiumhydrate to the other. The two substances react upon each other andcombine, forming sodium hypochlorite, which bleaches the tissue immersedin its solution.Block System.A system of signalling on railroads. The essence of the system consistsin having signal posts or stations all along the road at distancesdepending on the traffic. The space between each two signal posts istermed a block. From the signal posts the trains in day time aresignalled by wooden arms termed semaphores, and at night by lanterns.The arms may be moved by hand or by automatic mechanism depending inpart on electricity for carrying out its functions. Thus in theWestinghouse system the semaphores are moved by pneumatic cylinders andpistons, whose air valves are opened and shut by the action of solenoidmagnets, q. v. The current of these magnets is short circuited bypassing trains, so as to let the valves close as the train passes thesignal post. The block system causes the semaphore to be set at "danger"or "caution," as the train enters the next block. Then the followingtrain is not allowed to enter the block until the safety signal isshown. The Westinghouse system provides for two semaphores on a post,one indicating "danger" as long as the train is on the next block; theother indicating "caution" as long as the train is on the next twoblocks. The rails form part of the circuit, their joints being bridgedby copper wire throughout the block, and being insulated where theblocks meet.Block Wire.In the block system a wire connecting adjacent block-signal towers orsemaphore poles.Blow-pipe.A name sometimes given to an electric experiment illustrating therepulsion of electrified air particles from a point held at highrelative potential. A metallic point, placed on the prime conductor ofan electric friction or influence machine, becomes highly electrified,and the air becoming excited is repelled and acts upon the candle flame.If the candle is placed on the conductor and a point held towards it therepulsion is still away from the point.84 STANDARD ELECTRICAL DICTIONARY.Blow-pipe, Electric Arc.A name sometimes given to devices for using the voltaic arc to producelocal heating effects. The directive action of the magnet may be used toforce out the arc like a blow-pipe flame, or a blast of air may bedirectly applied for the same purpose.Blue-stone.A trade name for crystallized copper sulphate, used in Daniell's andgravity batteries.Boat, Electric.A boat propelled by electricity. The electricity drives a motor whichactuates a screw propeller. The current is generally supplied by astorage battery. When used on rivers charging stations are establishedat proper places. When the boat is used as a tender or launch for asteam ship, such as a war-vessel, the battery is charged by a plant onboard the ship. From their noiselessness electric boats are peculiarlyavailable for nocturnal torpedo operations, and the universal equipmentof modern war-ships with electric lightning and power plants makes theiruse possible at all points. This type is often termed an electriclaunch, and most or all electric boats fall under this category.Bobbins.A spool of wood or other material wound with insulated wire. In atangent galvanometer the bobbin becomes a ring, with a channel toreceive the winding. As the ring is not infinitely large compared to theneedle the tangent law is not absolutely fulfilled. It is mostaccurately fulfilled (S. P. Thomson) when the depth of the groove orchannel in the radial direction bears to the breadth in the axialdirection the ratio of square root of 3 to the square root of 2 orapproximately 11 : 9Body Protector.A metallic short circuit connected with the wrists and lower legs of thehuman body, so that if by accident an active circuit is grounded by thehands and body of the workman wearing it, most of the current will passthrough the wire conductors, thus avoiding the vital organs of the body.Boiler Feed, Electric.An apparatus by which an electric current acting on an electro-magnet,or other equivalent device, opens the water supply when the water levelin a boiler sinks too low, and cuts off the water supply as the waterlevel rises.Boiling.In secondary batteries the escape of hydrogen and oxygen gas when thebattery is charged. The bubbling of the escaping gases produces theeffect of boiling.85 STANDARD ELECTRICAL DICTIONARY.Boll.An absolute, or c. g. s., unit of momentum; a gram moving at the rate ofone centimeter per second; a gram-kine (see Kine); a unit proposed bythe British Association.Bolometer.An apparatus for detecting small amounts of radiant energy (radiantheat, so called). A coil suspended by a fine wire or filament so as tobe free to rotate under the effect of force is made up of two paralleland equal wires, insulated from each other, but connected so thatparallel currents sent through them go in opposite direction througheach. This coil is hung in a strong electro-magnetic field produced by alarge coil surrounding it. When a current passes through the suspendedcoil no effect will follow, because the oppositely wound portionscounteract each other exactly. In the circuit with one half of thesuspended coil is an exceedingly thin strip of platinum wire. The otherhalf of the coil has no strips. Both halves unite after leaving thecoil. If now the strip of platinum is heated its conductivity isaffected and its half of the coil receives less current than the otherhalf. This disturbs the balance and the coil swings through a small arc.This apparatus may be made very sensitive, so that an increase oftemperature of 1/1400º F., 9/70000°C. (1/14000º F.) will be perceptible.Another construction takes the form of a Wheatstone Bridge, q. v., inwhose arms are introduced resistances consisting of bands of iron, .5Millimeter wide (.02 inches), .004 millimeter (.00016 inch) thick, andfolded on themselves 14 times so as to make a rectangular grating, 17 x12 millimeters (.68 x .48 inch). The least difference of heat applied tothe grating affects the galvanometer.Synonym-Thermic Balance.Boreal Pole.The south pointing pole of the magnet. (See Austral Pole.)Bot.A colloquial expression for the English Board of Trade unit ofElectrical Supply. It is formed of the initials of the words "Board ofTrade." (See Unit, Board of Trade.)Box Bridge.A constriction of Wheatstone's Bridge in which the necessary resistancecoils are contained in a single box with plugs for throwing the coils inand out of circuit, and connections to bring the coils into thedifferent arms of the system. The cut shows a box bridge. Connectionsfor the galvanometer, battery wires, and terminals of the unknownresistance are provided, by which its resistances and the connectionsare brought into the exact relations indicated in the conventionaldiagram of Wheatstone's bridge. (See Wheatstone's Bridge.)Referring to the cut, the battery wire, say from the zinc plate,connects at A1, thereby reaching A, its true connecting point. To B1 oneend of the galvanometer circuit or lead is attached, thereby reaching B,its true connecting point. To C are connected the other end from thegalvanometer and one end of the unknown resistance. The other end of theunknown resistance, and the other end of the battery wire, in this casefrom the carbon plate, connect to D. At G is an infinity plug, as it iscalled. When out it breaks the circuit.In use after the connections are made the key is depressed and thegalvanometer observed. The resistance is changed until no action of thegalvanometer is produced by closing the circuit when the ratio of theresistances of the arms gives the proportion for calculating the unknownresistances.Synonym--Commercial Wheatstone Bridge, or commercial form of same.Fig. 65. TOP OF BOX BRIDGE.86 STANDARD ELECTRICAL DICTIONARY.Boxing the Compass.Naming the thirty-two points of the compass in order, and in sequence toany point called out at random. There are many exercises in the relativesailing points and bearings that come under the same head. Thus thedirection of two given points being given by names of the compasspoints, it may be required to state the number of points intervening.Brake, Electro-magnetic.A brake to stop a wheel from rotating. It comprises a shoe, or sometimesa ring, which by electro-magnetic attraction is drawn against therotating wheel, thus preventing it from turning, or tending to bring itto rest. (See Electro-magnet, Annular.)Fig. 66. ELECTRIC BRAKE.87 STANDARD ELECTRICAL DICTIONARY.Branch.A conductor branching from a main line. Sometimes the term is restrictedto a principal conductor, from which current is distributed.Branch Block.In electric wiring of buildings, a block of porcelain or other materialwith grooves, holes and screws for the connection of branch wires to amain wire. Its functions are not only to afford a basis for connectingthe wires, but also to contain safety fuses. As when a branch wire istaken off, fuses have to be put in its line, the branch block carriesthese also. One end of each fuse connects with a main wire, the otherend connects with one of the wires of the branch leader or wire.Porcelain is a favorite material for them, as the fusing or "blowingout" of the safety fuses cannot set it on fire.Branch Conductor.A parallel or shunt conductor.Brazing, Electric.Brazing in which the spelter is melted by means of electricity; eithercurrent incandescence or the voltaic arc may be used. It is identical ingeneral with electric welding. (See Welding, Electric.)Branding, Electric.A system of branding in which the heat of electrically ignited orincandescent conductors is used to produce or burn in the marks upon thesurface. For the alternating current a small transformer is connected toor forms part of the tool.88 STANDARD ELECTRICAL DICTIONARY.Brassing.The deposition of a coating of brass by electrolysis. The plating bathcontains both copper and zinc. As anode a plate of brass is used. Theoperation must be constantly watched. The deposition of both metals goeson simultaneously, so that a virtual alloy is deposited. By changingthe depth of immersion of the anode the color of the deposit is varied.As a formula for a brassing bath the following are typical. They areexpressed in parts by weight.(a) For iron and steel.I.Sodium Bisulphate, 200Potassium Cyanide, 70 per cent., 500Sodium Carbonate, 1,000Water, 8,000II.Copper Acetate, 125Zinc Chloride, 100Water, 2,000Add the second solution to the first.(b) For zinc.I.Sodium Bisulphate, 700Potassium Cyanide, 70 per cent., 1,000Water, 20,000II.Copper Acetate, 350Zinc Chloride, 350Aqua Ammoniae, 400Water, 5,000Add the second solution to the first.Use a brass anode; add more zinc to produce a greenish color; morecopper for a red color. A weak current gives a red color; a strongcurrent lightens the color. The battery power can be altered, a largeror smaller anode can be used, or a copper or zinc anode can be used tochange the color of the deposit. The bath may vary from 1.036 to 1.100sp. gr., without harm.Break.A point where an electric conductor is cut, broken, or opened by aswitch or other device, or simply by discontinuity of the wires.Break-down Switch.A switch used in the three-wire system to provide for the discontinuanceof the running of one of the dynamos.By connecting the positive and negative bus wires to one terminal of theactive dynamo, and the neutral bus wire to the other terminal, onedynamo will supply the current and the system operates like a two-wiresystem, but can only be used for half its normal capacity.Breaking Weight.The weight which, applied in tension, will break a prism or cylinder, asan electric current conductor.89 STANDARD ELECTRICAL DICTIONARY.Breath Figures, Electric.If a conductor is electrified and placed upon a piece of glass, it willelectrify the glass in contact with it by conduction or discharge. Onremoving the conductor the glass remains electrified. The localizedelectrification is shown by breathing gently on the glass, when aspecies of image of the conductor is produced by the condensed moisture.A coin is often used for conductor.Breeze, Electric.A term in medical electricity, used to designate the silent or brushdischarge of high tension electricity. As an instance of its employment,the electric head bath (see Bath, Electric Head,) may be cited. Thepatient forming one electrode, being insulated and connected to one ofthe conductors, the other conductor, on being brought near his person,discharges into his body.Bridge.(a) A special bar of copper connecting the dynamos to the bus wire, q. v.,in electric lighting or power stations.(b) Wheatstone's bridge, q. v., and its many modifications, all of whichmay be consulted throughout these pages.British Association Bridge.The type of Wheatstone bridge used by the committee of the associationin determining the B. A. ohm; the meter bridge, q. v.Broadside Method.A method of determining the magnetic moment of a magnet. The magnet, n,s, under examination is fixed so that it is at right angles to themagnetic meridian, M, R, which passes through its own center and that ofa compass needle. From the deflection of the latter the moment iscalculated.Fig. 67. BROADSIDE METHOD.Bronzing.In electro-plating the deposition of a mixture or virtual alloy ofcopper and tin. In general manipulation it resembles the operation ofdepositing gold and silver alloy, or of brassing.For bronzing the following bath is recommended:Prepare each by itself (a) a solution of copper phosphate and (b) asolution of stannous chloride in a solution of sodium pyrophosphate. Fora, dissolve recently precipitated copper phosphate in concentratedsolution of sodium pyrophosphate. For b, add to a saturated solution ofsodium pyrophosphate solution of stannous chloride as long as theprecipitate which is formed dissolves. Of these two solutions add to asolution of sodium pyrophosphate which contains about 1.75 oz. of thesalt to the quart, until the precipitate appears quickly and of thedesired color. For anodes use cast bronze plates. Sodium phosphate mustbe added from time to time; if the deposit is too light add coppersolution, if too dark add tin solution. (W. T. Brannt.)90 STANDARD ELECTRICAL DICTIONARY.Brush.In electric current generators and motors, the pieces of copper or othermaterial that bear against the cylindrical surface of the commutator arethus termed. Many different constructions have been employed. Some haveemployed little wheels or discs bearing against and rotating on thesurface of the commutator. A bundle of copper strips is often employed,placed flatwise. Sometimes the same are used, but are placed edgewise.Wire in bundles, soldered together at their distant ends have beenemployed. Carbon brushes, which are simply rods or slabs of carbon, areused with much success.Synonym--Collecting Brush.Brush, Carbon.A brush for a dynamo or motor, which consists of a plate or rod ofcarbon, held in a brush holder and pressed against the commutatorsurface.Brushes, Adjustment of.In electric current generators and motors, the brushes which bear uponthe commutator when the machine is in action need occasional adjustment.This is effected by shifting them until sparking between them and thecommutator is nearly or quite suppressed.Fig. 68. BRUSH HOLDER.Brushes, Lead of.In a dynamo electric generator, the lead or displacement in advance ofor beyond the position at right angles to the line connecting the polesof the field magnet, which is given the brushes. In a motor the brushesare set back of the right angle position, or are given a negative lead.(See Lag.)91 STANDARD ELECTRICAL DICTIONARY.Brush Holders.The adjustable (generally) clutch or clamps for holding the commutatorbrushes of a dynamo, which keep them in contact with the commutator, andadmit of adjustment by shifting backward and forward of the brushes tocompensate for wear. They are connected to and form part of the rocker,q. v. By rotating the latter the brush-holders and brushes are carriedin one direction or other around the commutator, so as to vary the leadas required.Brush, Pilot.A third brush, used for application to different parts of a revolvingarmature commutator to determine the distribution of potentialdifference between its different members. (See Curve of Distribution ofPotential in Armature.) One terminal of a volt-meter is connected to oneof the regular brushes, A, of a dynamo; the other to a third brush, p,which is pressed against different portions of the commutator of thedynamo. The readings of the volt-meter are plotted in a curve ofdistribution of potential.Fig. 69. PILOT BRUSH.Brush, Rotating.Brushes for taking off the current from dynamo commutators, or givingcurrent connection to motors, whose ends are in the form of rollerswhich rotate like little wheels, and press against the commutatorsurface.Brush, Third.A third brush is sometimes provided in a dynamo for regulating purposes.Applied to a series machine it adjoins one of the regular brushes anddelivers its current to a resistance, to whose further end the regularcircuit is connected. By a sliding connection the resistance is dividedbetween the third brush circuit and the regular circuit, and by varyingthe position of this contact regulation is obtained.It is to be distinguished from the pilot brush used for determining thecharacteristic of the commutator, although based on the same generalprinciples.Fig. 70. THIRD BRUSH REGULATION.92 STANDARD ELECTRICAL DICTIONARY.Brush, Wire Gauze.A collecting or commutator brush for a dynamo or motor, which brush ismade of wire gauze rolled up and compressed into shape.Buckling.The bending up and distortion of secondary battery plates. It is largelydue to over-exhausting the batteries. Where the E. M. F. is neverallowed to fall below 1.90 volt it is far less liable to occur.Bug.Any fault or trouble in the connections or working of electricapparatus.Bug Trap.A connection or arrangement for overcoming a "bug." It is said that theterms "bug" and "bug trap" originated in quadruplex telegraphy.Bunsen Disc.In photometry, the Bunsen Disc is a piece of paper upon whose centre aspot is saturated with melted paraffin, or a ring of paraffined surfacesurrounds an untouched central spot. If placed in such a position thatit receives an equal illumination on each side, the spot almostdisappears. It is used on the bar photometer. (See Photometer, Bar.)Synonym--Grease Spot.93 STANDARD ELECTRICAL DICTIONARY.Buoy, Electric.A buoy for use to indicate channels or dangers in harbors and elsewhere,which carries an electric light, whose current is supplied by cable fromshore. It has been proposed to use glass tubes exhausted of air andcontaining mercury, which, as moved by the waves, would produce aluminous effect. A fifty-candle power incandescent lamp is an approvedsource of light.Burner, Electric Gas.A gas burner arranged for the flame to be lighted by electricity. Ittakes a great variety of forms. In some cases a pair of terminals arearranged near the flame or a single terminal is placed near the metaltip, the latter forming one of the terminals. The spark is generallyproduced by an induction coil, or a spark coil. The gas may first beturned on and the spark then passed. Sometimes the turning of the gascock of an individual burner makes and breaks a contact as it turns, andthereby produces simultaneously with the turning on of the gas a sparkwhich lights it.Another form is wholly automatic. A pair of electro-magnets are attachedbelow the base of the burner, one of which, when excited, turns on thegas, and the other one when it is excited turns it off. At the same timea spark is produced with the turning on of the gas so that it islighted. Thus, by use of a automatic burner, a distant gas burner can belighted by turning an electric switch. An out-door lamp may be lightedfrom within a house.The increasing use of electric incandescent lamps, lighted by theturning of a switch, tends to displace electric gas burners. The latterhave been classified into a number of types depending on theirconstruction.Burners are sometimes connected in series with leads from an inductioncoil. Then the gas is turned on all at once, and a succession of sparkspassed until the gas is all lighted. The ignition is practicallyinstantaneous.Button, Push.A species of switch which is actuated by the pressure of a button. Inits normal position the button is pressed outwards by a spring, and thecircuit is open. When pressed inwards, it closes the circuit. Whenreleased it springs backward and opens the circuit again.They are principally used for ringing bells. If the latter are of theautomatic type, they ring as long as the button is pressed.For door-bells and room-bells, the button often occupies the center of arosette of wood or bronze or other ornamental piece. Sometimes, as shownin the cut, they are constructed for use on floors to be pressed by thefoot. The general principle of their construction is shown, although themethod of making the contact varies.Synonym--Press Button.Fig. 71. FLOOR PUSH BUTTON.94 STANDARD ELECTRICAL DICTIONARY.Burning.(a) In a dynamo, the production of shifting and temporary arcs betweenthe commutator and brushes, which arcs produce heat enough to injure theparts in question.(b) In electro-plating, a defect due to too strong a current inproportion to the strength of solution and area of electrodes. Thisgives a black or badly-colored deposit.Bus Rod.A copper conductor used in electric lighting or power stations, toreceive the current from all the dynamos. The distributing leads areconnected to the bus wires.In the three-wire system there are three; in the two-wire system thereare two bus wires.The name is undoubtedly derived from "omnibus."The bus wires may be divided into positive, negative, and, in thethree-wire system, neutral bus wires.Synonyms--Omnibus Rod, Wire, or Bar--Bus Bar, or Wire.Buzzer.An electric alarm or call produced by a rapid vibration of electric makeand break mechanism, which is often magnified by enclosure in aresonating chamber, resembling a bell, but which is not struck ortouched by the vibrating parts. Sometimes a square wooden box is used asresonator.Fig. 72. BUZZER.95 STANDARD ELECTRICAL DICTIONARY.B. W. G.Abbreviation for Birmingham Wire Gauge. (See Wire Gauge, Birmingham.)