... 1906]DISCUSSIONATNEWYORK.707physicalrelationtoarationalbasis.Idiscussthispointratherfully on page 28 5 of Vol.XX of the InstituteTRANSACTIONS.(b)InconnectionwithDr. Steinmetz& apos;sreferenceto the influence of vibration on the BandHcurve,Icalledattentiontoapaper of mine*inwhichvibrationswere,usedin the determilnation of whatIcallanormalcurve of BandH.C.P. Steinmetz (byletter):(1)Regarding the ... 710ALTERNATING-CURRENTWAVE-FORM.[Sept. 28 the sampleundertest.Infact,evenwhen the utmostprecau-tionsaretakentokeep the impedance of the circuitexteriorto the magnetizingcoilassmallaspossible,thisexternalim-pedancemaybe the controllingfactorin the circuit,particularlyforhighvalues of the flux-density,andcorrespondinglowvalues of the permeability.Asthisexternalimpedanceispracticallyconstantundersuchconditions, the currentin the magnetizingcoilmayhaveverynearlyasineform,andconsequentlyproduceamuchdistortedwave of inducedelectromotiveforcein the sample. The accompanyingoscillographrecordsgive the pressure-wavesundervariousconditionsinducedinasecondarywinding on asample of ironweighingabout6lb. The samplewasbuiltup of punchingsin the form of ahollowsquare5in.outside,3in.inside,eachsheet0.14-in.thick. The magnetizingcoilhad 20 turns. The totalresistance of the circuitbetweengeneratorandsamplewasabout0.75ohm, of which0.3ohmwasin the instrumentsin the circuitand0.45in the step-downtransfomer(one-halfakilowatt, 20 to1ratio). The magnetizingcoilit-selfhadpracticallynoresistance. The source of pressurewasasmall110-voltmotor-generator,givingasine-waveelectro-motiveforce.Curve1isfor 25 cyclesandamaximumflux-density of 6,850lines of inductionpersquarecentimeter.Curve 2 isfor 25 cyclesandamaximumflux-density of 11,300Curve3isfor 25 cyclesandamaximumflux-density of 12, 800.Asine-wave of pressureat the terminals of the magnetizingcoilwouldhavegivenflux-densities of 7,000, 12, 000and15,-000linesrespectivelv. The followingtablegivesforanothersample the flux-densitiescalculated on the basis of asinewaveelectromotiveforceand the trueflux-densitiesdeterminedfrom the averagevalues of the electromotiveforcewave:BTrueBRatio of TrueBtoCasldc-Calculated on basislatedB. of sinewave.60Cycles. 25 Cycles.60Cycles. 25 Cycles.4,0004,0004,0001.001.007,0006,8006,5000.970.9310,0009,4009,1000.940.91 12, 00011,00010,6000. 92 0.8815,000 12, 2000.8117,50013 ,20 00.76 20 ,00014,1000.71A.HenryPikler(byletter):ProfessorBedell'spapergives the impressionthat the hysteresis loopis the onlycause of the dis-tortion of alternating-currentwave-forms.Thisisnotso. The ÆTHERFORCE 6 92 ALTERNATING-CURRENTWAVE-FORM.[Sept. 28 DISCUSSION ON " THE EFFECT OF IRONINDISTORTINGALTER-NATING-CURRENTWAVE-FORM"ATNEWYORK,SEPTEMBER 28 ,1906.CharlesProteus Steinmetz: Thispaperdealswith the wave-shapedistortionproducedinalternating-currentcir-cuitsby the introduction of iron.Itisatheoreticalpaper,andwhile of scientificinterestappearsatfirst of ratherlittlepracticalvalueto the electricalengineer.Thereis,however,to-dayonlyaveryshortstepbetweenpurescientificinvestiga-tionandengineeringpractice;andIhopetoshowyouithat the phenomenadealtwithinthispaper,andsimilarphenomena,are of verygreatpracticalimportanceinalternating-currentdis-__.LjL__ ... 1906]DLICUSSIONATNEWYORK.695zerovalue.Thatis, the harmonicssymmetricalwithregardto the electromotiveforcearenoticeableonlyat the zeropoint,asaflatteningout. The magnetismcurveatthispointishorizontal,sothat the resultantcurrentcurvemustbehorizontalalso.Thiscouldbeexpressedbystatingthat the distortion of the wave of the excitingcurrentisdue,notto the energylostin the iron,butto the magneticcharacteristicor the bending of the satura-tioncurve,andthereforeitisthiscurvewhichweshouldendeavortoconstruct, the magneticcharacteristicasitwouldbegivenbyamagneticcycle,in the absence of hysteresis loss.Thiswouldprobablygiveapproximately the higherharmonicsin the ex-citingcurvewave.Sometimein1881or18 82 Dr.Froehlichnoticedthat the magneticcharacteristic of the dynamomachinecouldbeap-proximatelyvrepresentedbyaparaboliccurve.Dr.Kennellyshowed,in`1891*,that the BHcurve,ormagneticcharacteristic of iron,for the highervalues,couldbeexpressedbyaparaboliccurve,an~equation of the seconddegree.Usingthisequation of aparabolafor the relationbetweenBandH,therecouldbefoundastrictlymathematicalcurve,aboutlikeBinFig.5,.whichcombinedwithasinewaverepresenting the hysteresis loss,wouldfairlycloselyrepresent the distortedwave of excitingcurrent.Indealingwith hysteresis wehavetokeepinmind the differencebetweenmagnetic hysteresis and the energylostin the iron.Ifironisexposedtoanalternatingmagneticfield, the loss of energythattakesplacein the iron,bysomeform of magnetic*MagneticReluctance,byA.E.Kennelly,TRANSACTIONSA.I.E.E.Vol.8,page485.ÆTHERFORCE...