0.9985 (Ayrton)0.99941 (Boltzman.)The specific gravity of air under standard conditions 15.5° C (60° F.)and 760 mm. barometric pressure (30 inches) is taken as unity as astandard for gases.[Transcriber's note: Argon accounts for 0.9340%. It was discovered in1894, two years after this book.]Air-Blast.(a) In the Thomson-Houston dynamo an air-blast is used to blow away thearc-producing spark liable to form between the brushes and commutator.It is the invention of Prof. Elihu Thomson. The air is supplied by apositive action rotary blower connected to the main shaft, and driventhereby. The wearing of the commutator by destructive sparking is thusprevented.A drum H H is rotated, being mounted on the axis X of the dynamo. As itrotates the three vanes are thrown out against the irregular shapedperiphery of the outer case T T. The arrow shows the direction ofrotation. The air is thus sent out by the apertures a a. O is theoil-cup.(b) The air-blast has also been used by Prof. Thomson in experimentswith high frequency currents of high potential. By directing a blast ofair against a spark discharge between ball terminals of an alternatingcurrent, the nature of the current was changed and it became capable ofproducing most extraordinary effects by induction.14 STANDARD ELECTRICAL DICTIONARY.Fig. 5. AIR BLOWER FOR THOMSON'S DYNAMO.Air Condenser.A static condenser whose dielectric is air. The capacity of an aircondenser in farads is equal toA / ( 4.452E12 * t )in which A is the area of one sheet or sum of the areas of one set ofconnected sheets in square inches and t is the thickness of the layer ofair separating them.A convenient construction given by Ayrton consists in a pile of glassplates P separated by little bits of glass F of known thickness, threefor each piece. Tin-foil T is pasted on both sides of each piece ofglass and the two coatings are connected. The tin-foil on each secondplate is smaller in area than that on the others. The plates areconnected in two sets, each set comprising every second plate. For A inthe formula the area of the set of smaller sheets of tin-foil is taken.By this construction it will be seen that the glass does not act as thedielectric, but only as a plane surface for attachment of the tin-foil.Posts E E keep all in position. One set of sheets connects with thebinding post A, the other with B.The capacity of any condenser with a dielectric of specific inductivecapacity i is given by the formula:( i *A^1 ) / ( 4.452E12 * t1 )The air condenser is used for determining the value of i for differentdielectrics.Fig. 6. AIR CONDENSER.15 STANDARD ELECTRICAL DICTIONARY.Air Gaps.In a dynamo or motor the space intervening between the poles of thefield magnet and the armature. They should be of as small thickness, andof as extended area as possible. Their effect is to increase themagnetic reluctance of the circuit, thereby exacting the expenditure ofmore energy upon the field. They also, by crowding back the potentialdifference of the two limbs, increase the leakage of lines of force fromlimb to limb of the magnet.Air Line Wire.In telegraphy the portion of the line wire which is strung on poles andcarried through the air.Air Pump, Heated.It has been proposed to heat portions of a mercurial air pump to securemore perfect vacua, or to hasten the action. Heating expands the air andthus produces the above effects.16 STANDARD ELECTRICAL DICTIONARY.Air Pump, Mercurial.An air pump operated by mercury. The mercury acts virtually as thepiston, and the actuating force is the weight of the column of mercury,which must exceed thirty inches in height. There are many types.Mercurial air pumps are largely used for exhausting incandescent lampchambers. (See Geissler Air Pump,--Sprengel Air Pump.)Air Pumps, Short Fall.A mercurial air pump in which the fall of mercury or the height of theactive column is comparatively small. It is effected by using severalcolumns, one acting after the other. A height of ten inches for eachcolumn suffices in some forms. Enough columns must be used in successionto make up an aggregate height exceeding 30 inches.Fig. 7. BURGLAR ALARM SWITCH OR CIRCUIT BREAKER.Fig. 8. BURGLAR ALARM SWITCH OR CIRCUIT BREAKER.Alarm, Burglar.A system of circuits with alarm bell extending over a house orapartments designed to give notice of the opening of a window or door.As adjuncts to the system the treads of the stairs are sometimesarranged to ring the bell, by completing a circuit when trod on. Doormats are also arranged to close circuits in like manner.17 STANDARD ELECTRICAL DICTIONARY.For doors and windows switches are provided which are open as long asthe door or window is closed, but which, on being released by openingthe door or windows, automatically close the circuit. The circuitincludes an alarm bell and battery, and the latter begins to ring andcontinues until stopped, either by the closing of the door or by aswitch being turned. The connections are sometimes so contrived that thereclosing of the door or window will not stop the bell from ringing.The cuts show various switches for attachment to doors and windows. Itwill be seen that they normally keep the circuit closed, and that it isonly open when pressure, as from a closed door, is brought upon them. Inthe case of a door a usual place for them is upon the jamb on the hingeside, where they are set into the wood, with the striking pinprojecting, so that as the door is closed the pin is pressed in, thusbreaking the circuit.Sometimes the connections are arranged so as to switch on the electriclights if the house is entered. Special annunciators showing where thehouse has been entered are a part of the system. A clock which turns thealarm on and off at predetermined hours is also sometimes used.The circuits may be carried to a central station or police station. Oneform of burglar alarm device is the Yale lock switch. This is a contactattached to a Yale lock which will be closed if the wrong key is used,completing a circuit and ringing a bell.Fig. 9. BURGLAR ALARM SWITCH OR CIRCUIT BREAKER.Alarm, Electric.An appliance for calling attention, generally byringing a bell. It is used to notify of water-level in boilers or tanks,of entrance of a house, or of other things as desired. It is evidentthat any number of alarms could be contrived.18 STANDARD ELECTRICAL DICTIONARY.Alarm, Fire and Heat.An alarm for giving notice of the existence of a conflagration. Such aresometimes operated by a compound bar thermostat (see Thermostat), whichon a given elevation of temperature closes a circuit and rings anelectric bell. Sometimes the expansion of a column of mercury whenheated is used. This, by coming in contact with one or two platinumpoints, completes a circuit, and rings the bell.The identical apparatus may be used in living rooms, greenhouses.factories and elsewhere, to give an alarm when the temperature rises orfalls beyond predetermined limits.Alarm, Overflow.An alarm to indicate an overflow of water has been suggested on thelines of a contact completed by water, or of the elements of a batterywhich would be made active by water. Thus two sheets of metal might beseparated by bibulous paper charged with salt. If these sheets wereterminals of a circuit including a bell and battery, when water reachedthem the circuit would be closed and the bell would ring. It was alsoproposed to use one copper and one zinc sheet so as to constitute abattery in itself, to be thrown into action by moisture. These contactsor inactive batteries could be distributed where water from an overflowwould be most likely to reach them.Alarm, Water Level.An alarm operated by a change of water level in a tank or boiler. By afloat a contact is made as it rises with the water. Another float may bearranged to fall and close a contact as the level falls. The closing ofthe contacts rings an electric bell to notify the attendant in charge.Alcohol, Electrical Rectification of.A current of electricity passed through impure alcohol between zincelectrodes is found to improve its quality. This it does by decomposingthe water present. The nascent hydrogen combines with the aldehydes,converting them into alcohols while the oxygen combines with the zincelectrode.Alignment.The placing in or occupying of the same straight line. The bearings of ashaft in dynamos, engines, and other machinery have to be in accuratealignment.Allotropy.The power of existing in several modifications possessed by somesubstances, notably by chemical elements. Instances of the allotropicstate are found in carbon which exists as charcoal, as graphite(plumbago or black lead), and as the diamond. All three are the sameelemental substance, although differing in every physical and electricalproperty.19 STANDARD ELECTRICAL DICTIONARY.Alloy.A mixture, produced almost universally by fusion, of two or more metals.Sometimes alloys seem to be chemical compounds, as shown by their havinggenerally a melting point lower than the average of those of theirconstituents. An alloy of a metal with mercury is termed an amalgam. Animportant application in electricity is the use of fusible alloys forfire alarms or for safety fuses. German silver is also of importance forresistance coils, and palladium alloys are used for unmagnetizablewatches. An alloy of wrought iron with manganese is almostunmagnetizable, and has been proposed for use in ship building to avoiderrors of the compass.Alloys or what are practically such can be deposited by electrolysis inthe electro- plater's bath. We give the composition of some alloysinteresting to the electrician.Solder: Lead 1 part Tin 2 parts" " " 1 "" " " 2 "German Silver: Copper, 2 parts; Nickel, 1 part;Zinc, 1 part (used for resistances).Platinum, Silver Alloys: Platinum, 1 part;silver, 2 parts (used for resistances.)Palladium alloys for watch springs. (See Palladium.)Alphabet, Telegraphic.The combinations of sounds, of dots and dashes marked on paper, ofright-hand and left-hand deflections of a needle, of bells of differentnotes, or of other symbols by which a fixed combination is expressed foreach character of the alphabet, for numerals, and for punctuation. Whilethe code is designed for telegraphic uses it can be used not only forthe conveyance of signals and messages by the electrical telegraphs, butalso by any semaphoric or visual system, as by flashes of light,movements of a flag or even of the arms of the person signalling.In the English and continental needle telegraphy in which the message istransmitted by the movements of an index normally vertical, butoscillating to one side or the other under the influence of the current,the latter being controlled by the transmitter of the message, the lefthand swings of the needle are interpreted as dots, the right hand asdashes.This system enables one alphabet to be translated into the other, orvirtually one alphabet answers for both Morse and needle transmitters.There are two principal telegraphic alphabets, the American Morse andthe International codes. They are very similar, their essentialdistinction being that spaces are used in the American code, while theyare excluded from the International code.In the American Morse system the message is now universally received bysound. (See Sounder--Sound Reading.)20 STANDARD ELECTRICAL DICTIONARY.The two codes or telegraphic alphabets are given here.THE INTERNATIONAL ALPHABET.Parenthesis, - . - - . -Understand, ... - .I don't understand, ..-- ....--..Wait, .-. . .Erase, ... ... ...Call signal, -.-.-.-End of message, .-.-.-.Cleared out all right, .-..-..-.A .- L .-.. W .--B -... M -- X -..-C -.-. N -. Y -.--D -.. O --- Z --..E . P .--.F ..-. Q --.- Ch ----G --. R .-. Ä .-.-H .... S ... Ö ---.I .. T - Ü ..--J .--- U ..- É ..-..K -.- V ...- Ñ --.--NUMERALS1 .---- 4 ....- 8 ---..2 ..--- 5 ..... 9 ----.3 ...-- 6 -.... 0 -----7 --...[Transcriber's note: The original image of the dot/dash pattern is somewhatambiguous. Since there may be differences from contemporary specifications,the original image is included.][Image of page 20: THE INTERNATIONAL ALPHABET.]21 STANDARD ELECTRICAL DICTIONARY.PUNCTUATION, ETC.,Period (.) ... ...Comma (,) .-.-.-Query(?) ..--..Exclamation (!) --..--Apostrophe (') .----.Hyphen (-) -....-Fresh paragraph, .-.-..Inverted commas, -..-.THE AMERICAN ALPHABET.A .- L ----(Continuous) W .--B -... M -- X .-..C ..s. N -. Y ..s..D -.. O .s. Z ….E . P .....F .-. Q ..-. Ch ----G --. R .s.. Ä .-.-H .... S ... Ö ---.I .. T - Ü ..--J - . - . U ..- É ..-..K -.- V ...- Ñ --.--NUMERALS1 .--. 4 ....- 8 -....2 ..-.. 5 --- 9 -..-3 ...-. 6 ... ... 0 -----(Continuous)7 --..[Transcriber's Note: The "s" in the American Code indicates a "space". Ileave the following to the reader's imagination. See the originalimage.]Comma (,)Semicolon (;)Colon (:)Colon Dash (:~)Period (.)Interrogation (?)Exclamation (!)Dash (-)Hyphen (-)Pound Sterling (£)Shilling Mark ( )[Image of page 21: THE AMERICAN ALPHABET.]22 STANDARD ELECTRICAL DICTIONARY.[Transcriber's Note: I leave these to the reader's imagination. See thefollowing original image.]Dollars ($)Decimal Point (.)Cents (c)Paragraph ()Pence (d.)Fractional Mark (--)Capitalized LetterItalics or UnderlineColon followed by Quotation :"Parenthesis ( )Brackets [ ]Quotation Marks " "Quotation within a Quotation " ' ' "[Image of page 22: THE AMERICAN ALPHABET.]The principal differences in the two codes are the use of spaces in theAmerican code, such being excluded from the International code. Thisaffects the letters C, R, Y, & Z.The following diagram, due to Commandant Perian, enables the lettercorresponding to an International code sign to be rapidly found with theexception of R.<- dot start dash ->/ \E T/ \ / \I A N M/ \ / \ / \ / \S U R W D K G O/ \ / \ / \ / \ / \ / \ / \ / \H V F U L A P J B X C Y Z Q Ô CHFig. 10. Diagram for translating the Morse Alphabet.In order to find what letter corresponds to a given sign, starting fromthe top of the diagram, each line is traced down to a bifurcation,taking the right hand line of each bifurcation for a dash, and the lefthand line for a dot, and stopping when the dots and dashes are used up.Thus, for example,the signal -.- - leads us to the letter d,the signal - - - - to the letter j and so on.23 STANDARD ELECTRICAL DICTIONARY.Alternating. adj.Term descriptive of a current changing periodically indirection. (See Current, Alternating.)Synonyms--Oscillatory--periodic--undulatory--harmonic.Alternating Current Arc.The arc produced by the alternating current. It presents severalpeculiarities. With an insufficient number of alternations per second itgoes out. As the carbons wear away equally it is adopted for such lampsas the Jablochkoff candle, (see Candle, Jablochkoff). As no crater isformed the light is disseminated equally both up and down. For thisreason to get full downward illumination a reflector is recommended.Alternating Current System.A system of electric distribution employing the alternating current. Fortransmission in the open air or in conduits a high potential circuit isused, from 1,000 to 10,000 volts being maintained at the centralstation. Two leads unconnected at the end lead from the station. Wherecurrent is desired a converter or transformer (see Converter) is placed,whose primary is connected to the two leads bridging the intervalbetween them. From the secondary the house leads are taken with aninitial potential in some cases of 50 volts. The converters are thus allplaced in parallel. By law or insurance rules the converters aregenerally kept outside of buildings. Where no secondary current is takenfrom the converters very little primary current passes them on accountof their counter-electromotive force. As more secondary current is takenthe primary increases and this accommodation of one to the other is oneof the interesting and valuable features. Street lamps are sometimesconnected in series. Each lamp in such case is in parallel with a smallcoil with iron core. While the lamp is intact little current passesthrough the coil. If the lamp is broken, then the converter impedes thecurrent by its spurious resistance, q. v., just enough to represent andreplace the resistance of the extinguished and broken lamp filament.(See Meter, Alternating Current; Motor, Alternating Current.)Alternation.The change in direction of a current. The number of such changes isexpressed as number of alternations; thus a current may have a frequencyof 500 or 20,000 alternations per second.[Transcriber's note: One alternation per second is now called one hertz.]Alternation, Complete.A double alternation; a change from one directionto the other and back again to the original phase. A symbol derived fromits graphic representation by a sine curve is used to indicate it. Thesymbol is ~24 STANDARD ELECTRICAL DICTIONARY.Alternative Path.A second path for a current appearing as a disruptivedischarge. Where two paths are offered the discharge, as it is ofalternating or oscillatory type, selects the path of leastself-induction. Thus a thick bar of copper, with no air gap, may beabandoned by the current in favor of a small iron wire with an air gap,but which has less self-induction.The lightning arresters, q. v., for the protection of telegraph officesare sometimes based on these principles. A path of very high resistancebut of small self-induction is offered between the line and the earth.This the lightning discharge selects in preference to the instrumentswith their iron cores, as the latter are of very high self-induction.Alternator.A dynamo electric generator supplying an alternating current. (SeeDynamo, Alternating Current.)Synonym--Alternating current generator or dynamo.Alternator, Constant Current.An alternating current dynamo supplying a current of unvarying virtualamperage. Alternators of this type are constructed with an armature ofhigh self-induction. Sometimes fine winding contained in deep peripheralnotches in the core-discs is employed to magnify the self-induction.Such generators are employed for series lighting, especiallyarc-lighting.Aluminum.A metal; one of the elements; symbol: Al.Atomic weight: 27.4. Equivalent: 9.13. Valency: 3.Specific gravity: 2.6. It is a conductor of electricity.Relative resistance annealed, (Silver = 1) 1.935Specific resistance at 0ºC (32°F.) 2.912 microhmsResistance of a wire at 0ºC (32°F.)a) 1 foot long, weighing 1 grain, 0.1074 ohms.b) 1 foot long, 1/1000 inch thick, 17.53 "c) 1 meter long, weighing 1 gram, 0.0749 "d) 1 meter long, 1 millimeter thick 0.03710 "Resistance of a 1-inch cube at 0ºC (32°F.) 1.147 microhmsElectro-chemical equivalent. .0958 (hydrogen == .0105)25 STANDARD ELECTRICAL DICTIONARY.Amalgam.(a) A combination or alloy in which one of the constituents is mercury.Usually the term is applied to an alloy of a single metal with mercury.Some metals readily form amalgams; such metals are: Gold, zinc, silver,lead and others; some, such as platinum and iron, form amalgams onlyunder exceptional circumstances.(b) The word is also applied to compositions for application to thecushions of frictional electric machine in which cases it is often amisnomer. True amalgams used for this purpose are made as follows:(a) Tin, 1 part; Zinc, 1 part; Mercury, 2 parts (Kienmayer).(b) Tin, 2 parts; Zinc, 3 parts.(c) Tin, 3 parts; Zinc, 5 parts; Mercury, 4 parts.(d) Zinc, 1 part: Mercury, 4 parts; Mercury, 9 parts. [sic]The tin, if such is used, (formula a, b and c) is first melted, the zincis added in successive portions. The mercury, which must be heated, isslowly poured into the melted alloy after removal of the latter from thefire, and the mixture, while making, is constantly stirred. It is keptstirred or rubbed in a mortar until cold. Sometimes it is poured intowater and kept in constant agitation until cold. It is thus obtained ina granular condition, and is pounded in a mortar until reduced topowder. It must be dried and kept in tightly stopped bottles and isapplied to the cushions after they have been greased. It is to benoticed that it is said that alloy (d) requires no pulverization beyondconstant rubbing in a mortar as it cools. Sometimes the amalgam isshaken about in a wooden tray with chalk while cooling. The action ofamalgams is not very clearly understood. Some claim that there is achemical action, others that they simply act as conductors, others thatthey are more highly negative to the glass than the leather of thecushions.Graphite or sulphide of tin (mosaic gold) are sometimes used to coat thecushions; it is these that are sometimes incorrectly called amalgams.Amalgamation.The application of mercury to a metal with which it forms an amalgam, orwith which it amalgamates. Battery zincs are amalgamated in two ways. Inthe immersion method, the plate is dipped into an acid solution ofmercuric chloride or nitrate. The latter is best. In the directapplication method the plate is first wet all over with dilute acid anda little mercury is dropped upon it and is rubbed over the surface witha rag or, what is better, with a piece of galvanized iron. A very littlemercury answers the purpose. The whole surface of the plate should beleft as bright as silver. (See Action, Local.)Amber.Amber is a fossil resin, supposed to be a product of the extinct PinitesSuccinifer and other coniferous trees. Most of it is gathered on theshores of the Baltic between Koenigsberg and Memel. It is also found insmall pieces at Gay Head, Mass., and in New Jersey green sand. It isfound among the prehistoric remains of the Swiss Lake dwellers. Whenrubbed with a cloth it becomes excited with negative electricity. TheGreek word for it is electron, which gave the name electricity to themodern science. Thales of Miletus, 600 B. C., and Theophrastus, about300 B. C., both mention its electric properties or power of attractingsmall objects when rubbed.26 STANDARD ELECTRICAL DICTIONARY.Ammeter.The commercial name for an ampere-meter, an instrument designedto show by direct reading the number of amperes of current which arepassing through a circuit.A great variety of ammeters have been invented, based on differentprinciples. The definitions following this one give some idea of thelines of construction followed.Synonym--Ampere meter.Ammeter, Ayrton's.A direct reading instrument for measuring current intensity.A solenoid receives the current. In the axis of the solenoid an irontube is suspended by a long spiral spring that passes down within it,and the upper end of which spring is fastened to the glass top of theinstrument. The tube is provided with proper guides so as to maintain avertical position, and is free to rotate. Its upper end carries anindex.The whole operates as a magnifying device. A slight longitudinaldisplacement of the tube causes it to rotate through a considerableangle by the action of the spring. By properly proportioning the parts,the angle of displacement of the index is directly proportional to thecurrent between 15º and 270º angular displacement.The same instrument is wound for use as a volt-meter.Its principal fault is its restricted range.Ammeter, Commutator.A commutator ammeter is one whose windings consist of separate strands,each of any desired number of turns, and provided with a commutatingattachment for throwing them into series or into parallel as desired.The essential condition is that all the wires shall be of equalresistance and of equal number of turns. Such an instrument can be usedfor heavy or light currents. Two sets of graduations are marked on itsscale if it is a calibrated instrument. (See Calibration.) Commutatorvolt-meters are constructed on the same principle.Ammeter, Cunynghame's.A modification of the Siemens' electro-dynamometer. (SeeElectro-dynamometer, Siemens'.) An electro-magnet with very massive coreis excited by the current. As the core is of small reluctance thestrength of the magnet is nearly proportional to the current strength.Between the poles of the magnet a soft iron armature or induced magnetis pivoted. It carries a pointer so adjusted that when the axis of thesoft iron magnet is at an angle of about 30º with the line joining thepoles of the electro-magnet the pointer will indicate zero.The soft iron armature is so massive that the magnetism induced in it isproportional to the strength of the electro-magnet. Hence the coupleexerted by the electro-magnet on the pivoted armature will beproportional to the square of the current.The armature is retained in place by a spiral spring lying in line withits axis of rotation. The instrument is operated as a zero readinginstrument. The current is passed through it. The needle is deflected;it is brought back to zero by turning a milled head which twists thespring. The current will be proportional to the square root of the angleof displacement of the milled head. A scale with index is provided,giving directly the square roots of the angle over which the pointer ismoved.The same instrument is wound for use as a volt-meter.27 STANDARD ELECTRICAL DICTIONARY.Ammeter, Eccentric Iron Disc.This ammeter comprises a cylindrical electro-magnet excited by thecurrent to be measured. A disc of iron free to rotate is suspended onpivots below it. A piece is cut off the disc at one part of itsperiphery so as to give more metal to one side than to the other. In itszero position this portion of the disc swings towards the magnet. As thelatter is more and more excited the other or more projecting portion ofthe disc turns towards it, being attracted like an armature, and movesagainst the force of gravity, the disc rotating. An index attached tothe disc swings over the face of a graduated scale. The disc is socounterpoised that in its natural position the index points to zero.Ammeter, Electro-magnetic.An ammeter depending for its working upon the action of anelectro-magnet, which is excited by the current to be measured.Ammeter, Gravity.An ammeter whose hand or index is drawn into the zero position bygravity, and whose displacement therefrom is produced by the action ofthe current to be measured.Fig. 11. GRAVITY SOLENOID AMMETER.Ammeter, Magnetic Vane.A fixed plate of soft iron is placed within a coil. Facing it is asecond disc free to move or swing on an axis. When the field is excitedthe two repel each other because like polarity is induced in each, andthe motion of the movable disc indicates the strength of the current.The same instrument is wound for high resistance and constitutes aMagnetic Vane Voltmeter.28 STANDARD ELECTRICAL DICTIONARY.Ammeter, Magnifying Spring.A solenoid ammeter in which a spiral spring is used to convert thelongitudinal motion of the armature or movable core into a rotary motion(see Ammeter, Ayrton's) and magnify the apparent range of motion.Ammeter, Permanent Magnet.An ammeter with a magnetic field produced by a permanent magnet.Ammeter, Solenoid.An ammeter in which the attraction, when a current is passing throughit, exerted by a hollow coil of wire upon an iron bar or tube in linewith its axis, is utilized to indicate the strength of current. The baris drawn into the coil to different extents proportional to theattraction. As an example see Ammeter, Ayrton's, and cut of GravityAmmeter.Ammeter, Spring.An ammeter in which the part moved by the current is controlled orbrought to the zero position by a spring.Ammeter, Steel Yard.A solenoid ammeter in which the solenoid core is suspended verticallyfrom the short end of a steel yard fitted with a sliding weight. Thecurrent passes through the solenoid coil and attracts or draws downwardsthe coil. A sliding weight is moved in and out on the long steel-yardarm which is graduated for amperes. In use the weight is slid out untilthe arm is in equipose; the divisions give the amperes.Fig. 12. STEEL YARD AMMETER.29 STANDARD ELECTRICAL DICTIONARY.Ammunition Hoist, Electric.An apparatus for use on ships for hoisting ammunition to the guns by anelectric elevator. The characteristic feature of it is that a constantmotion of the switch or handle is required to keep it in action. If theoperator is shot so as to be incapacitated from taking charge of theswitch, the hoist stops until another is assigned to it.Amperage.Current intensity expressed in amperes, as an amperage of ten amperes.Ampere.The practical unit of electric current strength. It is the measure ofthe current produced by an electro-motive force of one volt through aresistance of one ohm. In electric quantity it is the rate of onecoulomb per second. It is one-tenth the absolute C. G. S. unit ofcurrent strength. Its best analogy is derived from water. Assuming theelectric current to be represented by a current of water, the pressure,head, or descent producing such current would be the electro-motiveforce. The current might be measured in gallons (or other unit) passedper second. In the analogy these gallons would be coulombs. But it mightbe measured by reference to a standard stream, as for instance, thestream which would pass through a hole an inch square under a givenhead, say six inches of water. This unit is the miner's inch, and is theexact analogy of the ampere. A current of water may flow at the rate ofso many miner's inches, just as a current of electricity may flow at therate of so many amperes. In neither case it will be noted is there anyreference to time. "An ampere per second" is a redundant expression, andmeans no more than "an ampere"; an "ampere-second," on the other hand,is a coulomb. The number of coulombs passed per second gives the amperesof current.For value of ampere, see Coulomb.[Transcriber's note: The SI definition of an ampere: A current in twostraight parallel conductors of infinite length and negligiblecross-section, 1 metre apart in vacuum, would produce a force equal to2E-7 newton per metre of length.]Fig. 13. THE MINER'S INCH AS AN ANALOGY FOR THE AMPERE.30 STANDARD ELECTRICAL DICTIONARY.Ampere, Arc.A conductor bent into the arc of a circle, and employed in measuring theelectric current by the electric balance.Ampere-currents.The currents assumed to be the cause of magnetism. (See Magnetism,Ampere's Theory of.)Ampere-feet.The product of amperes of current by the length, in feet, of a conductorpassing such current. It may be in empiric calculations of dynamo ormotor construction, but is little used. One ampere-foot is a current ofone ampere passing through one foot length of a conductor, or one-tenthampere through ten feet, and so on.Ampere-hour.The quantity of electricity passed by a current of one ampere in onehour. It is used by electric power and lighting companies as the unit ofenergy supplied by them, because they maintain a constant potentialdifference in their leads, so that only the amperes and hours needmeasuring or recording to give the energy, viz. : volt-ampere-hours.The same unit is applied to batteries to indicate their potentialenergy, because they also are assumed to be of constant voltage orelectro-motive force.Ampere-meters.The product of amperes of current by the length, in meters, of aconductor carrying such current. One ampere-meter is a current of oneampere passing through one meter of a conductor.The term must not be confused with the identically spelled Ampere-meter,a synonym for Ammeter.Ampere-minute.The quantity of electricity passed by a current of one ampere in oneminute; sixty coulombs.Ampere Ring.A conductor forming a ring or circle used in electric balances formeasuring currents. (See Balance, Ampere.)Ampere-second.The quantity of electricity passed by a current of one ampere in onesecond; the coulomb, q. v.Amperes, Lost.In a shunt or compound-wound dynamo, part of the total amperes ofcurrent produced in the armature coils go through the shunt, and hence,do not appear in the outer circuit. S. P. Thompson has proposed the term"lost amperes" for this portion of the current.Ampere's Memoria Technica.An expression of the effect of a current on a magnetic needle. If weimagine the observer in the line of the current and facing the magneticneedle, the current entering by his feet and leaving by his head, thenorth pole is deflected to his left.31 STANDARD ELECTRICAL DICTIONARY.Ampere-turns.The amperes of current supplied to a magnet coil multiplied by thenumber of turns the current makes in the coil. If the coil is wound twoor three in parallel, the virtual turns by which the amperes aremultiplied are one-half or one-third the actual turns of wire.Synonym--Ampere Windings.Ampere-turns, Primary.The ampere-turns in the primary coil of an induction coil ortransformer.Ampere-turns, Secondary.The ampere-turns in the secondary coil of an induction coil ortransformer.Amplitude of Waves.Waves are distinguished by length and amplitude. The latter, in the caseof transverse waves, such as those of water and of the ether, correspondwith and measure the height from lowest to highest point, or from valleyto summit of the waves in question. In the case of longitudinal waves,such as those of the air, due to sounding bodies, the ratio of degree ofrarefaction to degree of condensation existing in the system is theamplitude. The latter can be graphically represented by a sinuous line,such as would represent the section of a transverse wave. Ether wavesare produced by heated bodies and by electro-magnetic impulses, as inthe discharge of the Leyden jar.The amplitude of a wave, other things being equal, is the measure of itsintensity. Thus, the louder a sound the greater is the amplitude of thesystem of waves to which it is due. The same applies to ether waves,whether they are perceived in the electro-magnetic, light, orheat-giving modification. As the amplitude of ether waves cannot beaccurately known, amplitude is a relative term and is not statedgenerally in any absolute unit.Analogous Pole.One of the elements of a pyro-electric crystalline substance, such astourmaline. When heated, such bodies acquire electrical properties. Ifof such crystalline form that they are differently modified at the endsof their crystalline axis, by hemihedral modifications, the ends may bedifferently affected. One end may show positive electricity when thetemperature is rising, and negative when falling. Such end is thencalled the analogous pole. The opposite end presents, in such cases, theopposite phenomena; becoming negative when the temperature is rising,and becoming positive when it is falling; such end is called theantilogous pole.Analysis.The determination of the elements of a case. It may be chemical, andconsist in finding what a substance consists of; it may be mathematical,and consist in determining the unknown quantities in a problem; or itmay belong to other branches of science. The term has a very extendedapplication. Where the constituents are only determined in kind it iscalled qualitative analysis; where their quantity or percentage isascertained it is called quantitative analysis.32 STANDARD ELECTRICAL DICTIONARY.Analysis, Electric.Chemical analysis by electrolytic methods. (See Electrolytic Analysis.)Analyzer, Electric.An apparatus used in investigations on electric ether waves. It consistsof a series of parallel metallic wires. When the electric waves havebeen polarized, the analyzer will only permit them to go through itintact, when the plane of vibration of the waves is parallel to itswires.Anelectrics.(a) Bodies which do not become electrified by friction; a termintroduced by Gilbert, now little used, as all bodies developelectricity under proper conditions by contact action; the reverse ofidioelectrtics.(b) Also a conductor of electricity, the reverse of a dielectric, q. v.(See Conductor.)It will be seen that Gilbert's anelectrics were, after all, the same asthe modern anelectrics, i.e., conductors.Anelectrotonus.A term used in medical electricity or electro-therapeutics to indicatethe deceased functional activity induced in a nerve by the proximity ofthe anode of an active electric circuit completed through the nerve. Theconverse of Kathelectrotonus.Angle of Declination.The angle of error of the magnetic needle or compass, measuring theextent of its deviation from the meridian in any locality. It is theangle between the plane of the magnetic axis of a magnetic needle freeto take its natural position, and the geographical meridian, the needlebeing counterpoised if necessary, so as to hold an absolutely horizontalposition. The deviation is expressed as being east or west, referringalways to the north pole. (See Magnetic Elements.)Synonym--Variation of the Compass.[Transcriber's note: See Agonic Line.]Angle of the Polar Span.In a dynamo or motor the angle subtended by the portion of a pole piecefacing the armature, such angle being referred to the centre of thecross-section of the armature as its centre.33 STANDARD ELECTRICAL DICTIONARY.Angular Velocity.The velocity of a body moving in a circular path, measured withreference to the angle it passes over in one second multiplied by theradius and divided by the time. A unit angle is taken (57°.29578 =57° 17' 44".8 nearly) such that it is subtended by a portion of thecircumference equal in length to the radius. Hence, the circumference,which is 360°, is equal to 2*PI*unit angle, PI being equal to 3.1416--."Unit angular velocity" is such as would in a circle of radius = 1represent a path = 1, traversed in unit time = 1 second. If the radiusis r and the angle passed over is theta, the distance is proportional tor*theta; if this distance is traversed in t seconds the angular velocityis theta / t. The angular velocity, if it is multiplied by r, thetaexpressing a distance, will give the linear velocity. The dimensions ofangular velocity are an angle (= arc / radius) / a Time = (L/L)/T =(T^-1).The velocity expressed by the rate of an arc of a circle of unit radius,which arc subtends an angle of 57° 17' 44".8, such arc being traversedin unit time, is unit angular velocity.Animal Electricity.Electricity, notably of high tension, generated in the animal system, inthe Torpedo, Gymnotus and Silurus. The shocks given by these fish aresometimes very severe. The gymnotus, or electric eel, was elaboratelyinvestigated by Faraday. It has the power of voluntarily effecting thisdischarge. There is undoubtedly some electricity in all animals. Thecontact of the spinal column of a recently killed frog with the lumbarmuscles produces contraction, showing electric excitement. Currents canbe obtained from nerve and muscle, or from muscle sides and muscle cuttransversely, in each case one thing representing positive and the othernegative elements of a couple.Angle of Inclination or Dip.The angle which the magnetic axis of a magnet, which magnet is free tomove in the vertical plane of the magnetic meridian, makes with ahorizontal line intersecting such axis. To observe it a specialinstrument, the dipping compass, inclination compass, dipping needle, ordipping circle, as it is called, is used. (See Elements, Magnetic,--Dipping Needle,--Compass, Inclination.)Angle of Lag.The angle expressing the displacement of the magnetic axis of thearmature core of a dynamo in the direction of its rotation. (See Lag.)Lag is due to the motion of the armature core.Angle of Lead.The angle expressing the displacement in the direction of rotation ofthe armature of a dynamo which has to be given the brushes to compensatefor the lag. (See Lag.) This is positive lead. In a motor the brushesare set the other way, giving a negative angle of lead or angle ofnegative lead.Anion.The electro-negative element or radical of a molecule, such as oxygen,chlorine or the radical sulphion. (See Ions.) It is the portion whichgoes to the anode, q.v., in electrolytic decomposition.34 STANDARD ELECTRICAL DICTIONARY.Anisotropic. (adj.)Unequal in physical properties, as in conduction and specific inductivecapacity, along various axes or directions. An anisotropic conductor isone whose conductivity varies according to the direction of the current,each axis of crystallization in a crystalline body marking a directionof different conductivity. An anisotropic medium is one varying in likemanner with regard to its specific inductive capacity. In magnetism ananisotropic substance is one having different susceptibilities tomagnetism in different directions. The term is applicable to other thanelectric or magnetic subjects.Synonym--AEolotropic.Annealing, Electric.Annealing by the heat produced by the passage of the electric currentthrough the body to be annealed. The object is clamped or otherwisebrought into a circuit, and a current strong enough to heat it toredness, or to the desired temperature is passed through it.Annunciator.An apparatus for announcing a call from any place to another, as from aliving-room to an office in a hotel, or for announcing the entering ofany given room or window in a building protected by a burglar alarm.A usual system comprises for each annunciator an electro-magnet. Itsarmature is normally held away from its poles by a spring, and when inthat position a latch connected to the armature holds a little shutter.When by a push-button or other device a current is sent through acircuit which includes the electro-magnet the armature is attracted,this releases the latch and the shutter drops. In dropping it displays anumber, letter or inscription which indicates the locality of thepush-button or other circuit-closing device. Often annunciators areconnected in circuit with a bell.Fig. 14. ANNUNCIATOR.35 STANDARD ELECTRICAL DICTIONARY.Annunciator Clock.A clock operating an annunciator by making contact at determined times.Annunciator Drop.The little shutter which is dropped by some forms of annunciators, andwhose fall discloses a number, character or inscription, indicatingwhence the call was sent.Fig. 15. DROP ANNUNCIATOR.Fig. 16. ANNUNCIATOR DETACHING MECHANISM.Annunciator, Gravity Drop.An annunciator whose operations release shutters which fall by gravity.Annunciator, Needle.A needle annunciator is one whose indications are given by the movementsof needles, of which there is usually a separate one for each place ofcalling.Annunciator, Swinging or Pendulum.An annunciator which gives its indications by displacing from itsvertical position a pendulum or vertically suspended arm.36 STANDARD ELECTRICAL DICTIONARY.Anodal Diffusion.A term in electro-therapeutics; the introduction of a medicine into theanimal system by using a sponge-anode saturated with the solution of thedrug in question. On passing a current the desired result is secured bycataphoresis, q. v.Anode.The positive terminal in a broken metallic or true conducting circuit;the terminal connected to the carbon plate of a galvanic battery or toits equivalent in case of any other generator. In general practice it isrestricted to the positive terminal in a decomposition or electrolyticcell, such as the nickel anode in a nickel-plating bath or the anode ofplatinum in a gas voltameter. It is the terminal out of or from whichthe current is supposed to flow through the decomposition cell. Inelectro-therapeutics the term is used simply to indicate the positiveterminal. In an electrolytic cell the electro-negative substance oranion goes to the anode. Hence, it is the one dissolved, if either areattacked. The nickel, copper or silver anodes of the electroplaterdissolve in use and keep up the strength of the bath. The platinum anodein a gas voltameter is unattacked because the anion cannot act upon itchemically.Anodic Closure Contraction.A physiological change in a living subject produced by the closing ofthe electric current; the muscular contraction which takes place beneaththe anode applied to the surface of the body when the circuit is closed,the kathode being applied elsewhere; it is due, presumably, to directaction on the motor nerve. It is a term in electro-therapeutics. It isthe converse of anodic opening contraction, q. v. An abbreviation A. C.C. is often used to designate it.Anodic Duration Contraction.A term in electro-therapeutics. On the opening or closing of an electriccircuit, the anode of which is placed over a muscle, a contraction isobserved (see Anodic Closure Contraction--Anodic Opening Contraction).The above term is used to designate the duration of such contraction. Anabbreviation A. D. C. is often used to designate it.Anodic Opening Contraction.The converse of Anodic Closure Contraction, q. v.; it is the contractionof living muscle beneath or near the anode where the circuit, includingsuch anode and the body in its course, is closed; a physiologicalphenomenon observed in electro-therapeutics to which branch of sciencethe term belongs. An abbreviation A. O. C. is often used to designateit.Anodic Reactions.A term in electro-therapeutics; the diagnosis of disease by the actionsof the tissue near the anode of a circuit.Anti-Induction Conductor.A conductor constructed to avoid induction effects in the conductingelement. Many kinds have been made. A tubular metal shield or envelopewhich may be grounded will protect an enclosed conductor to some extent.Or the conductor may be a double wire twisted around itself, one branchbeing used for the regular and the other for the return circuit, thusconstituting a closed metallic circuit. The inductive effects are due tointerrupted or varying currents in neighboring wires and circuits. Manyanti-induction conductors have been invented and patented.37 STANDARD ELECTRICAL DICTIONARY.Anti-magnetic Shield.In general terms a hollow screen of soft iron designed to protect anymass of steel behind or enclosed by it from magnetization by any magnetnear it, such as a dynamo field magnet. This it does by concentratingthe lines of force within its own mass, so that the space within it orenclosed by it is comparatively free from lines of force. It is oftenapplied to watches, and is virtually an iron case in which they areenclosed.Antimony.A metal, one of the elements, atomic weight, 122:equivalent, 40.6 and 24.4; valency, 3 and 5;specific gravity, 6.8.It is a conductor of electricity.Relative resistance, compressed (silver = 1), 23.60Specific resistance, 35.50 microhms.Resistance of a wire,(a) 1 foot long, weighing 1 grain, 3.418 ohms.(b) 1 foot long, 1/1000 inch thick, 213.6 "(c) 1 meter long, weighing 1 gram, 2.384 "(d) 1 meter long. 1 millimeter thick, 0.4521 "Resistance of a 1-inch cube, 13.98 microhms.Approximate percentage resistance per degree C.(1.8º F. at 20º C. 88º F.) 0.389 per cent.Elcctro-chemical equivalent (hydrogen = .0105) .2560(See Thermo-Electric Series.)Anvil.An intermittent contact, or "make and break" of the current is sometimesproduced by directly pressing a key down upon a metallic surface, thetwo being terminals of the circuit. The surface or stud on which suchpressure is produced is called the anvil. The ordinary telegraph key,which makes a contact by the pressure of the operator's fingers does itby making a contact between a contact piece upon the front end of thekey and the anvil. In the induction coil the anvil is also found. Thusin the cut representing the end of an induction coil and its circuitbreaker in which O and O' and P and P' represent the secondary circuitterminal connections A is the core of soft iron wires, h is the anvil;the hammer when resting upon it so as to be in contact closes thecircuit. When the current coming from the primary to the post i, passesthrough the hammer and anvil h, and emerges by m, it magnetizes thecore; this attracts the hammer, which is made of or is armed with a massof iron. This breaks the circuit. The hammer falls at once on the anvil,again making the circuit, and the action is repeated with greatrapidity. Hammer and anvil or key and anvil connections should be madeof platinum.Fig. 17. INDUCTION COIL CIRCUIT BREAKER.38 STANDARD ELECTRICAL DICTIONARY.A. O. C.Abbreviation for Anodic Opening Contraction, q. v.Aperiodic. adj.In an oscillating apparatus, or in the oscillating member of apparatus,the fact of having no reference to time of vibration; dead-beat.Synonym. Dead-beat.39 STANDARD ELECTRICAL DICTIONARY.Fig. 18. ARAGO'S DISC.Arago's Disc.An apparatus consisting of a disc of copper mounted horizontally, or ona vertical spindle, and so arranged as to be susceptible of rapidrotation. Immediately over it, and best with a pane of glassintervening, a magnetic needle is mounted on a pivot directly over theaxis of the disc. If the disc is rotated the lines of force of themagnet are cut by it, and consequently currents are produced in thecopper. These currents act upon the needle and cause it to rotate,although quite disconnected. It is advisable for the needle to be strongand close to the disc, which should rotate rapidly.Arc v.To form a voltaic arc.Arc, Compound.A voltaic arc springing across between more than two electrodes.Arc, Metallic.The voltaic arc produced between terminals or electrodes of metal. Thecharacteristics of such arc as contrasted with the more usual arcbetween carbon electrodes are its greater length for the sameexpenditure of energy, its flaming character and characteristic colorsdue to the metals employed. It is sometimes, for the latter reason, usedin spectroscopic investigations.Arc Micrometer.A micrometer for measuring the distance between the electrodes of avoltaic arc.Arc, Simple.A voltaic arc produced, as usual, between only two electrodes.40 STANDARD ELECTRICAL DICTIONARY.Arc, Voltaic.The voltaic arc is the arc between two carbon electrodes slightlyseparated, which is produced by a current of sufficient strength andinvolving sufficient potential difference. The pencils of carbon aremade terminals in a circuit. They are first placed in contact and afterthe current is established they are separated a little. The current nowseems to jump across the interval in what sometimes appears an arch oflight. At the same time the carbon ends become incandescent. As regardsthe distance of separation with a strong current and high electro-motiveforce, the arc may be several inches long.The voltaic arc is the source of the most intense heat and brightestlight producible by man. The light is due principally to theincandescence of the ends of the carbon pencils. These are differentlyaffected. The positive carbon wears away and becomes roughly cupped orhollowed; the negative also wears away, but in some cases seems to haveadditions made to it by carbon from the positive pole. All this is bestseen when the rods are slender compared to the length of the arc.It is undoubtedly the transferred carbon dust which has much to do withits formation. The conductivity of the intervening air is due partly,perhaps, to this, but undoubtedly in great measure to the intenseheating to which it is subject. But the coefficient of resistance of theintervening air is so much higher than that of any other part of thecircuit that an intense localization of resistance occurs withcorresponding localization of heating effect. This is the cause of theintense light. Thus if the carbons are but 1/32 of an inch apart as in acommercial lamp the resistance may be 1.5 ohms. The poor thermalconductivity of the carbon favors the concentration of heat also. Theapparent resistance is too great to be accounted for by the ohmicresistance of the interposed air. A kind of thermoelectric effect isproduced. The positive carbon has a temperature of about 4,000° C.(7,232° F.), the negative from 3,000° C. (5,432° F.) to 3,500° C.(6,322° F.). This difference of temperature produces acounter-electro-motive force which acts to virtually increase theresistance of the arc. The carbon ends of an arc can be projected withthe lantern. Globules are seen upon them due to melted silica from thearc of the carbon.