None
M. F. in the primary circuit of a transformer of say 1000 volts, and o 0, the effective E. M. F. in the sec- ondary circuit, in step with o E. When the secondary FIG. 120. circuit is open, let o M, 400 /90°, be the effective M. M. F. in gilberts or ampere-turns required to maintain the c. E. M. F., o c ; then the primary current must be in phase with o M. JSTow suppose a non-inductive load connected 2T9 to the secondary circuit. The E. M. F., o e, will send a current through this circuit lagging in phase very little behind o «, and the M. M. F. of this current will be o w2, say 400 \~~5^. I" order to maintain the resultant M. M. F. o M, the primary M. M. F. must assume the position o w, or approximately 000 /H0° and thus approach in phase the impressed E. M. F., which will be equal but op- posite tO O E. If now, owing to magnetic leakage in the transformer, inductance appears in the secondary coil, the second- ary current and M. M. F. may lag 15°, as shown at A, FIG. 121. and the primary M. M. F., (o M - - o />ia), will become approximately 625 /125°. Again, if the same load in watts be applied inductively to the transformer, as, for example, an alternating-current motor, the power factor of the secondary circuit will be reduced, and a greater current strength will be required, which will lag con- sid,erably and the M. M. F. may become, as at B, 770 \ 60°. The primary component will be increased to approxi- mately 1100 /2<>°, and the components will be nearly in opposition. 280 The effect of this opposition in M. M. F.'S upon the leak- age through both coils is illustrated in Fig. 121. If om2 and 6 m, are in quadrature, each M. M. F. is at its maxi- mum when its neighbor is zero, and when as at A, rn is at its maximum, //i2, is absent, and the flux tli rough the reluctance R3, of the leakage path will be only that due to the magnetic drop in the reluctance R2, of the iron oc- cupied by the secondary coil. Similarly when m%, is at its maximum the flux through R3, is that due to the drop in KJ. When, however, the M. M. F.'S are forced into op- position, the leakage flux from each through K3, is in- creased. 274. The power factor of transformers varies not only with their load, but also with the nature of their load, for, when the secondary circuit is loaded inductively, the current in the secondary circuit lags considerably be- hind the impressed secondary E. M. F. Consequently the c. M. M. F. is brought more nearly in opposition to the primary M. M. F. The drop in each circuit is, therefore, increased as will be evident from an inspection of Figs. 120 and 121. Large transformers, whose power factor may be 0.995 at full non-inductive load, with a full load drop at secondary terminals of 1 per cent., may have a power factor of 0.90 with an inductive load, and have their full load drop at the same time increased to 4 per cent. On the other hand a condenser connected to secondary terminals tends to diminish the secondary drop and increase the power factor. Laboratory of Houston & Kennelly, Philadelphia. INDKX. Activity, Definition of 7 Activity in Carbon Voltaic Arc 217, 218 Admittance 249 Aero-Ferric Magnetic Cir- cuit, Calculation of. . . 109, no Alloys 26 All-Night Arc Lamps 224 Alternating-Current Arc Circuits 228, 229 Alternating Current, Defi- nition of 233 Alternating-Current Arc, Distribution of Light from 228, 229 Alternating Current, Mean or Average Strength of. . 46 Alternating-Current Trans- former 273 to 280 Alternating-Current Trans- former,AutomaticAdjust- mentsof 275, 276 Alternating-Current Trans- former. Definition of 273 Alternating-Current Trans- former, Hysteretic Loss in 276, 277 Alternating-Current Trans- former, Power-Factor of. 280 Alternating Currents 233 to 256 Alternating E. M. F., Defini- tion of 233 Alternating or Pulsatory Current , Determination of Strength of 46 Alternation, Definition of.. 234 Alternator and Continuous Current Generator, Es- sential Difference b e - tween 257 Alternator, Diphase 265 Alternator, Uniphase 265 Alternators 257 to 272 Alternators, Connection of in parallel 263 Alternators, Definition of. . 238 Alternators, Multiphase.... 265 Ampere, Definition of 42 Ampere-Hour, Commercial Unit of Electric Quantity 45 Arc Carbons , Consumption of 223 Arc, Counter-Electromotive Force of 217 Arc Lamps, All-night 224 Arc Lamp, Ordinary, Activ- ity of 7 Arc Lamps, Alternating- Current Circuit 228, 229 Arc Lamps, Double-Carbon 224 Arc Light Carbon, Positive Crater in 218 282 INDEX. Arc Light Circuits, Con- tinuous, Distribution of Potential in 226 Arc Light Dynamos 225 Arc Light Globes 231 Arc Light Projectors . . 229, 230, 231 Arc-Lights, Mean Horizon- tal Intensity of 221 Arc Lights, Mean Spherical Candle-power of 221 Arc Lighting 216 to 232 Armature of Dynamo and Motor, Circumstances Af- fecting Direction of Rota- tion of l87, 188 Armature Reaction i5o Armatures, Toothed Core of Dynamos I52 Attractive Electromagnets, Definition of II3 Attractive Force of Electro- magnets, Calculation of 114. 115, 116 Balances, Resistance, Vari- ous Forms of 28, 29 Balance, Wheatstone's.. 28, 29 Battery, Voltaic, Efficiency of 7i Begohm, Definition of r8 Bichromate Voltaic Cell . 84, 85 Bicrohm, Definition of 18 Bridge Boxes, Various Forms of 28, 39 Bridge, Wheatstone's. . . 28, 29 Brushes of Dynamo, Lead of- M 149 Brushes, Shifting of on Com- mutator f orVaryingSpeed of Continuous Current Motor 177> I78 C. E. M. F. of Polarization. . 81 c. G. s., Practical, Unit of E. M. F n c. G. s Units 4, 5 c. G. s. Unit of Force 5 c. G. s. Unit of Quantity. .. u Cable, Insulation Resi- stance of 35) 36 Candle-Foot 206 Candle-Power of Arc Lights, Mean Spherical 221 Candle-Power of Incandes- cent Lamp, Methods Pro- posed for Regulating, 2 1 2, 213 Candle, Standard 205 Capability, Electrical , of Voltaic Cell 69, 7o Carbon Voltaic Arc, Ac- tivity in 2i7, 218 Carbons, Cored 228 Carbons, Electro-plated 223 Carcel Lamp 205 Carcel-Metre 2o6 Carrying Capacity of Con- ductors 45 Cell, Voltaic, Bichromate, 82, 83 Cell, Voltaic, Clark Standard 88 'ell, Voltaic, Edison-La- lande 87, 88 •ell, Voltaic, Electrical Capability of 69, 7o Cell, Voltaic, Fuller .... 86, 87 lell, Voltaic, Gravity. . . 84, 85 Cell, Voltaic, Grenet 82, 83 INDEX. Cell, Voltaic, Leclanche... 85 Cell, Voltaic, Partz Gravi- ty 85, 86 Cell, Voltaic, Poggendorff, 82, 83 Cell, Voltaic, Silver Chlor- ide 87, 88 Cell, Voltaic, Smee 82 Centimetre-G r a m m e - Se- cond Unit of Activity. ... 7 Central Lighting Stations, Maximum Lighting Load of 212 Central Lighting Stations, Minimum Lighting Load of 212 Charge, Electric, and Ether Strains, Relation between 2 Charge, Negative 2 Charge, Positive 2 Circuit, Drop in 50 Circuit, Electric, Definition of 57 Circuit, Ferric Magnetic. . 93 Circuit Impedance 244 Circuit, Multiple-Series 60 Circuit, Reactance 244 Circuit, Resonant 248 Circuits, Conducting, Clas- sification of 57 Circuits, Magnetic 92 Circular Type of E. M. F. or Current 235 Clark Standard Cell 15 Clark Standard Cell, Tem- perature Coefficient of . . . 16 Clark Standard Voltaic Cell 88 Coefficient of Reduction from Capability to Out- put... 131, 132 Coils, Compensating 160 Combin ation Triphase Winding 268 Compensating Coils, of Dy- namo 160 Complex-Sinusoidal Wave. 258 Conductance, Definition of 25 Conductances, Formula for Calculating 25 Conducting Circuits, Classi- fication of 57 Conductivity. Definition of 25 Conductivity, Magnetic. ... 95 Conductor, Electric, Dissi- pation of Heat by 196 Conductor, Electric, Tem- perature Elevation of 198 Conductors, Carrying Capa- city of 45 Conductors, Safe Current Density in 45 Continuous-Current Dyna- mo, Reversibility of 170 Cooling of Wire, Effect of Covering on 198, 199 Co-periodic Simple-Harmo- nic E. M. F.'S, Vector Sum of 243 Cored Carbons 228 Coulomb, Definition of . . 1 1 , 42 Couple, Voltaic 66 Counter- E lectromotive Force, Development of, by Continuous Current . . 62 Counter- Electro motive Force of Arc 217 Counter- Electromotive Force of Arc, Origin of.. 218 Counter-Electromotive Force of Induction . . 62 284 INDEX. Counter- E lectromotive Force of Motor 170 Counter-E lectromotive Force of Polarization . 62 Counter-E lectromotive Force, Varieties of 62 Counter-E lectromotive Force, Virtual 62 Crater in Positive Arc Light Carbon 218 Current, Alternating, De- finition of 233 Current, Circular Type of Periodic-Alternating 235 Current Density 45 Current, Displacement, Probable Nature of 10 Current, Electric ... 41 to 48 Current, Electric, Does Not Pass Through Conductor 41, 42 Current, Periodic-Alternat- ing, Definition of 233 Current, Sinusoidal 236 Curve, Sinusoidal 237 Curve, Simple-Harmonic . . 237 Curve, Simple-Periodic 237 Curves of Reluctivity in Iron and Steel in Relation to Flux Density 107 Cut-Out, Film 213, 214 Cycle, Definition of 234 D. E. M. F 170 Daniell Voltaic Cell 84, 85 Density of Current 45 Density of Flux, Definition of 90 Depolarizer 8 1 Derived Circuit, Applica- tion of Ohm's Law to $2 Detectors, Phase 264 Diagram, Hysteretic 142 Dielectric Displacement , Current in 2 Dielectrics, Maintenance of Electric Displacements in 2 Difference of Potential ... 13 Differential Calculus, Sim- ple Explanation of 43 Direct Electromotive Force of Generator 1 70 Diphase, Alternator 265 Diphase, Connection of In- terconnected Circuits. . . . 266 Diphase Connections, Sep- arate Circuits 266 Diphase E. M. F.'S 266 Displacement Current, Probable Nature of 10 Displacement Flux, Nature of 2 Displacement Strain. ...9, 10 Displacement, Electric, Na- ture of 2 Double-Carbon Arc Lamps 224 Double-Fluid Cells, Defini- tion of 82 Drop in Circuit 50 Dynamo and Motor, Co- Generation of Electro- dynamic and Electro motive Forces in 169 Dynamo, Counter Electro- dynamic Force of 1 70 Dynamo-Electric Machine, Armature of 150, 151 Dynamo-Electric Machine, Classification of Losses in 137 INDEX. 285 Dynamo-Electric Machine, Electrical Losses in. . 138, 139 Dynamo-Electric Machine, Lead of Brushes of . . . . 149 Dynamo-Electric Machine, Limitations to Output of, Classification of 145 Dynamo-Electric Machine, Mechanical Lossesin, 137, 138 Dynamo-Electric Machine, Principles of Design of.. 133, 134, 135 Dynamo, the 128, 152 Dynamos and Motor, Dif- ference of Output of . 181, 182 Dyne, Definition of 5 Dyne Centimetre, Defini- tion of . . 6 E. M. F 9 to 16 E. M. F., Alternating, De- finition of 233 E. M. F., Circular Type of Periodic-Alternating 235 E. M. F., Direction of In- duced, Rule for Deter- mining 123,214 E. M. F., Effective, Value of 239 E. M. F., Monocyclic Dia- gram of 271 E. M. F., or Current, Alter nating Flat-top Type of.. 235 E. M. F. of Self-Induction . . 127 E. M. F. of Voltaic Cell, Cal- culation of 76, 77 E. M. F., Periodic Alternat- ing, Definition of 233 E. M. F., Self-Induced 127 E. M. F., Sinusoidal 236 E. M. F., Sources of, in Vol- taic Cell 67, 68 E. M. F.'S, Diphase 266 Earth's Crust, Resistance of 31, 32 Earth's Crust, Resistivity of Materials Forming. . . 30 Edison-Lalande Voltaic Cell 86, 87 Efficiency, Commercial, of Dynamo Electric Ma- chine 137 Efficiency of Electrical Dis- tribution, Definition of . . 51 Efficiency of Lamp 207 Efficiency of Lamp, Effect of Temperature on 207 Efficiency of Lamp, So- called 207 Efficiency of^Lamp, True. . 207 Efficiency of Voltaic Bat- tery 71 Electric Capability of Gene- rator 131 Electric Circuits 57, 64 Electric Discharge, Classi- fication of Effects of 3 Electric Displacement, Maintenance of, in Non- Conductors or Dielectrics 2 Electric Displacement, Nature of 2 Electric Motor, Continuous Current Type of . . . 168 to 192 Electric Railroad Motor. . . 180 Electric Sources 13 Electric Sources, Classifica- tion of 14 Electrical Effects . . . . i to 8 286 INDEX. Electrical Energy of Voltaic Cell, Cost of 69 Electrification, Nature of . . 10 Electro-Chemical Equiva- valents, Tables of 74 Electro-Dynamic Force of Dynamo 170 Electro-Dynamics . . .161 to 168 Electro-Dynamics, Defini- tion of 161 Electrolyte, Action of E.M.F. on 73 Electromagnet, Attractive Form of 119, 120 Electromagnet, Portative Form of 118, 119 Electromagnets 113 to 120 Electromagnets, Attractive, Definition of 113 Electromagnets, Computa- tion of Attractive Force of 114, 115, 116 Electromagnets, Determin- ation of Polarity of 113 Electromagnets, Dual Char- acter of Flux in 113 Electromagnets, Iron-clad. 119 Electromagnets, Induced or Structural Magnetic Flux of 113 Electromagnets, Portative, Definition of .... 113 Electromagnets, Prime or Magnetizing Flux of 113 Electromotive Force of Electric Sources 14, 15 Electro-plated Arc Carbons 223 Element of Voltaic Cell 66 Energy, Conservation of . . 4 Energy, Definition of 3 Energy, Doctrine of Con- servation of 4 Energy, Kinetic, Definition of 3 Energy, Potential, Defini- tion of 3 Energy, Potential, a Pos- .sible Variety of Kinetic Energy 4 Energy, Total Amount of, in Sun 7 Entrefer, Definition of, 150, 151 Equivalent, Electro-Chem- ical 74, 75 Equivalent Resistance 253 Erg, Definition of 6 Erg, Value of , 6 Ether, Stresses and Strains in i, 2 Excessive Heating of Dy- namo-Electric Machine, Limitations to Output of, Caused by 144, 145, 146 Factor, Impedance 254, 255 Feeders. 215 Ferric Circuit, Calculation of 108, 109 Ferric-Magnetic Circuit 93 Filament, Causes of De- crease of Cross-Sectional Area of 210 Filament, Coking of 209 Filament, Decrease of Area of Cross Section of 208 Filament, Disintegration of 208 Filament of Incandescent Lamp 210 INDEX. 287 Filament of Incandescent Lamp, Variation of, Dur- ing Use, 209 Film Cut-out 213, 214 First Harmonic, Frequency of 258, 259, 260, 261 Five-wire System 61 Fleming's Hand Rule for Direction of Induced E. M. F 123, 124 Fleming's Hand Rule for Motors 163 Flux Density, Definition of 90 Flux Density, Unit of 90 Flux, Displacement,Nature of 2 Flux Intensity, Definition of ? Flux, Magnetic 89 Flux, Magnetic, Convention as to Direction of 89 Flux, Physiologically Effec- tive 206 Force, Counter Electromo- tive of Motor 170 Force, Definition of 3 Force, Electric i Force, Electromotive and Electrodynamic, Co-gen- eration of in Dynamo and Motor 169 Force, Magnetic, Definition of 99, ioo Force or Stress, Electromo- tive, Cause of 2 Force, Varieties of 3 Formulas for Resistivity.22, 23 Fourier's Theorem 258 Frequencies, Luminous and Non-Luminous. .,...,., 201 Frequencies, Definition of. 234 Frequency of First Har- monic 258, 259, 260, 261 Frequency of Second Har- monic 258, 259, 260, 261 Fuller Voltaic Cell 86, 87 Fuses, Electric, Capacity of, for Heat 200 Galvanometer, High Grade Thomson's Mirror. .. .47, 48 Galvanometer, Shunt. . .36, 37 Galvanometer, Thomson's Mirror 36 Gases, Effect of Pressure on Resistivity of 26 Gauss, Definition of 90 Generator, Direct E. M. F. of 170 Generator, Electric Capa- bility of 131 Generator, Output of 130 Generator, Series Wound. . 154 Generator, Shunt- Wound .. 154 Gilbert, Definition of 92 Globes, Arc-light 231 Gravity Voltaic Cell. . . 84, 85 Grenet Voltaic Cell,. . . 82, 83 Harmonics 258 Heat, Development of in Safety Fuse. 200 Heat, Dissipation of, by Electric Conductor 196 Heat, Loss by Radiation . . 197 Heat, Radiation of 197 Heat, Unit of. 192 Heating, Electric. . . .193 to soo 288 INDEX. Heating, Excessive, of Dy- namo-Electric Machine, Limitations to Output of, Caused by 144, 145, 146 Hefner-Alteneck Lamp . . . 205 High Resistance Appara- tus, Effect of Leakage on Accuracy of 37 Hysteresis, Definition of. . . 139 Hysteresis, Magnetic . . 139, 140, 141, 142, 143 Hysteresis, Magnetic. Loss of Energy of 141 Hysteretic Diagram 142 Hysteretic Loss in Alter- nating-Current Trans- former 276, 277 Illumination, Physiological, Coefficient of 203 Illumination, Physiologic- ally Effective 203 Illuminating Power, Phys- iologically Effective. . 202, 203 Impedance Factor 254, 255 Impedance of Circuit 244 Incandescent Lamp, Activ- ity of 7 Incandescent Lamp, Me- thods Proposed for Re- gulating Candle-power of 212, 213 Incandescent Lighting.. 201 to 224 Induced Electromotive Force 121 to 128 Induced or Structural Mag- netic Flux of an Electro- magnet ii Inductance, Influence of on Sparking of Brushes of Dynamo 147, 148 Induction, Counter-Electro- motive Force of 62 Inductor Alternators 257 Insulation Resistance of Line or Conductor 33 Insulator, Circumstances Affecting Resistance of. . 33 Insulator, Oil 33, 34 Intake of Machine, Defini- tion of 8 Intensity, Maximum of Arc Light ., 221 Intensity, Mean Horizontal, of Arc Lights 221 Intensity of Flux, Defini- tion of ... 90 International c. G. s. Unit of Quantity n International Ohm , Defini- tion of 17 International Practical Unit of E. M. F ii Ions, Definition of. 73 Iron-clad Electromagnets. . 119 Joint Admittance 249, 250 Joint Resistance 51 Joule 194 Joule, Definition of 7 Kinetic Energy, Definition of 3 Kirchoff's Laws 52, 53 Laborer, Average Activity of 7 Lamp, Carcel 205 INDEX. 289 Lamp, Effect of Tempera- ture on Life of 207 Lamp, Efficiency of 207 Lamp Globe, Blackening of 208, 2ii Lamp, Hefner-Alteneck . . . 205 Lamp, Violle 205 Laws, Kirchoff's 52, 53 Lead of Dynamo Brushes.. 149 Leading Pole of Motor- Armature 186 Leakage Paths. Magnetic. . 96 Leakage, Magnetic, Effect of on Efficiency of Trans- former 277 Leclanche, Voltaic Cell. ... 85 Lesser Calorie 192 Light, Standard of 205 Lighting, Load of Central Stations 212 Limiting Current Strength in Wires 198, 199 Line or Conductor, Insula- tion Resistance of . . . .33, 34 Localized Vector 1 1 Loop, Conducting, Rotation of, in Magnetic Flux 126 Losses, Eddy Current, in Continuous-Current Mo- tors 174 Losses, Magnetic, in Dyna- mo-Electric Machine, 139, 140 Losses, Mechanical, in Dy- namo-Electric Machine, 137, 138, 139 Luminous and Non-Lumin- ous Frequencies 201 Luminous Radiation, Effect of Temperature on 204 M. M. F 89, 96 M. M F.. Unit of . . . 92 Machine, Definition of In- take of 8 Machine, Definition of Out- put of 8 Machine, Dynamo-Electric, Commercial-Efficiency of 137 Machine, Dynamo Electric, Principles UnderlyingDe- signof 133, 134, 135 Machine, Efficiency of 8 Magnetic and Material Fluxes, Difference be- tween 91 Magnetic Circuits 92 Magnetic Conductivity 95 Magnetic Force, Definition of 99, 100 Magnetic Flux. . . . 89, 104, 112 Magnetic Leakage, Effect on Efficiency of Trans- former 277 Magnetic Losses of Dyna- mo-Electric Machine 139, 140 Magnetic Permeability .... 95 Magnetic Reluctance 96 to 104 Magnetic Reluctance, and Magnetizing Force, Rela- tion between 101, 102 Magnetic Saturation 92 Magnetism Residual 93 Magneto-Dynamics, Defini- tion of 161 Magnetomotive Force 91 Magnetomotive Force, Structural 93 Mangin Reflector. . . . . .230, 231 Maximum Intensity of Arc Light 221 2go INDEX. Mean Horizontal Intensity of Arc Lights 221 Mean Spherical Can die- Power of Arc Lights 221 Megadyne , Approximate Value of 6 Megadyne, Definition of . . . 6 Megohm, Definition of 18 Megohm, Standard 30 Metal-Coated Arc Light Carbons 223 Metallic Reluctivity 103 Mho, Definition of 25 Microhm, Definition of ... 18 Molecules, Dis-associated. . 73 Molten-Platinum Standard 205 Monocyclic E. M. F., Dia- gram of 271 Monocyclic System 271 Monocyclic System Trans- former 272 Motion, Simple-Harmonic.. 236 Motor- Armature, Leading Pole of 186 Motor- Armature, Reaction of 186, 187 Motor-Armature, Toothed Core 185 Motor- Armature, Trailing Pole of 1 86 Motor-Armatures, Smooth Core. 185 Motor, Continuous-Current, Speed Varied by Shifting Brushes on Commutator 128, 177 Motor, Continuous-Current, under Constant Torque, Methods of Carrying Speed of... 177, 178, 179 Motor, Counter-Electromo- tive Force of 170 Motor, Electromotive Force of 62 Motor, How to Reverse Di- rection of. . .187, 188, 189, 190 Motor, Relation of Torque and Speed to Activity of 171 Motor, Series 179 Motor, Shunt 180 Motor, Starting Resistance of 181 Motor, Street-car 191 Motor, Torque of 167 Motor, Work Absorbed by, 170 Motors, Classification of for Torque and Speed of 171 Motors,Continuous-Current, Eddy Current Losses in.. 174 Motors, Electric, Weight of 190, 191 Multiphase Alternators 265 Multiphaser 265 Multiple Arc Lighting, Cost 227, 228 Multiple Circuit 59 Multiple-Series Circuit .... 60 Multiplying Power of Shunt 36, 37 Negative Arc Light Carbon, Nipple on 219 Negative Charge 2 Negative Plate of Voltaic Cell 66 Negative Pole of Voltaic Cell 66 Negative Resistivity Tem- perature Coefficient 23 INDEX. 291 Negative Terminal of Vol- taic Cell 66 Network of Conductors, Application of Ohm's Law to . 53 Nipple on Negative Arc Light Carbon 219 Non-Luminous Radiation.. 201 Obscure Radiation 201 Oersted, Definition of. .97 Ohm, International, Defi- nition of 17 Ohm, Multiples and Sub- Multiples of 17. 18 Ohm, Standard ....... 29, 30 Ohrn's Law ... ...49 to 56 Ohm's Law, Application of, to Branch Circuit 52 Ohm's Law, Application of, to Network of Conduc- tors 53 Oil Insulator 33, 34 Output of Dynamo Electric Machine, Classification of Limitations to 145 Output of Dynamos and Motors, Difference be- tween 181, 182 Output of Generator 130 Output of Machine 8 Parallel Connection of Al- ternators 263 Partz Gravity Voltaic Cell 85, 86 Paths, Magnetic Leakage. . 96 Period, Definition of 234 Periodic Alternating Cur- rent, Definition of 233 Periodic- Alternating E.M.F., Definition of 233 Periodic Alternating E.M.F., or Current. Peaked Type of 235 Periodic- Alternating E. M. F. , or Current, Sinusoidal Type of. 235 Permanent Magnetomotive Force 91 Permeability, Magnetic ... 95 Phase 238 Phase Detectors 264 Physiological Coefficient of Illumination 203 Physiologically Effective Flux 206 Physiologically Effective Illuminating Power. 202, 203 Physiologically Eilective Illumination 203 Plate, Negative, of Voltaic Cell 66 Plate, Positive, of Voltaic Cell 66 Poggendorff Voltaic Cell 82 , 83 Polarity, Nature of 2 Polarization, c. E. M. F. of.. 8r Polarization, Counter-Elec- tromotive Force of 62 Pole, Leading of Motor- Armature 1 86 Pole, Negative, of Voltaic Cell 66 Pole, Positive, of Voltaic Cell 66 Pole, Trailing of Motor- Armature 186 Portative Electromagnets, Definition of 113 292 INDEX. Positive Carbon, Rate of Consumption, of 228 Positive Charge 2 Positive Plate of Voltaic Cell... 66 Positive Pole of Voltaic Cell 66 Positive Terminal of Voltaic Cell 66 Potential Difference 13 Potential, Distribution of, in Continuous-Arc Light Circuits 226 Potential Energy, Difini- tion of 3 Power Factor of Alternat- ing Current Transform- ers 280 Practical Unit of E. M. F. . . u Practical Unit of Electric Resistance 17 Practical Unit of Heat. . . . 194 Projectors for Arc Lights.. 229, 230, 231 Quantity, Electric, Com mercial Unit of 45 Quegohm, Definition of 18 Radiation, Non luminous.. 201 Radiation, Obscure 201 Radiation of Heat 197 Radiation, Physiologically Effective Luminous, Var- iation of, with Current Strength 211 Radiation, Standard, of Physiologically Effective Luminous 205 Railroad Electric Motor. . . 180 Ratio of Transformation .. 273. 274 Reactance of Circuit 244 Reflector, Mangin. ... 230, 231 Regulation of the Dynamo 153. i 60 Reichsanstalt Unit 205 Reluctance, Magnetic,^ to 104 Reluctance, Magnetic, Defi- nition of 97 Reluctance, Unit of 97 Reluctivity 97 Reluctivity, Curves of, in Iron and Steel, in Rela- tion to Flux Density 107 Reluctivity, Curves of, in Iron and Steel, in Rela- tion to Magnetizing Force 102 Reluctivity, Metallic 103 Residual Magnetism 93 Resistance, Balances. ..28, 29 Resistance, Electric 17, 40 Resistance, Electric, Nature of Unknown 36 Resistance, Equivalent 253 Resistance, Insulation of Cable 35, 3& Resistance, Joint 51 Resistance of Insulator, Circumstances Affecting, 33 Resistance, Specific 18 Resistance, Specific, Mag- netic 97 Resistance, Starting of Mo- tor 181 Resistance, Surface Contact 39 Resistances, Formula for Calculating 25 Resistances, Methods of Measurement of ... .26 to 31 INDEX. 293 Resistivities, Diagram of, atDifferentTemperatures 21 Resistivities, Table of . .19, 20 Resistivities, Thermal, Table of. 196 Resistivity 18 Resistivity, Formulae 22 Resistivity, Temperature Coefficients 19 Reversibility of Continuous- Current Dynamo. .. .170, 171 Resistivity, Thermal 194 Resonant Circuit 248 S. H. M 236 Safety Fuse, Development of Heat in 200 Saturation, Magnetic 92 Search Lights 229 Second-Harmonic, F r e - quency of. . . 258, 259, 260, 261 Self. Induced E. M. F 127 Semi- Period of Alternating E. M. F. or Current Wave, Definition of 234 Series Arc Light Circuits .. 225, 226, 227 Series Circuit 58 Series-Connected In- candescent Electric Lamps 213, 214 Series Motor 179 Series Motor, Commutation of Field Coils of 179 Series Motor, Method of Varying Speed of 179 Series-Wound Machine 187, 188 Shunt, Alternating-Current Circuit, MultiplyingPower of 252 Shunt Circuit, Application of Ohm's Law to 52 Shunt, Continuous Current Circuit, Multiplying Power of 251 Shunt Galvanometer 36, 37 Shunt Motor 180 Shunt Motor, Care Re- quired in Starting 181 Shunt, Multiplying Power of 36, 37, 251 Shunt- Wound Machines, Direction of Rotation as Motors and Generators.. 187, 188 Silver Chloride Voltaic Cell 87, 88 Simple-Harmonic Curve. . . 237 Simple-Harmonic Motion . 236 Simple-Periodic Curve 237 Single-Fluid Cells, Defini- tion of 81 Sinusoidal Current 236 Sinusoidal Current Circuit, Activity of 253 Sinusoidal Curve 237 Sinusoidal E. M. F 236 Smee Voltaic Cell 82 Smooth Core Motor Arma- tures 185 Sources, Electric 13 Sources, Electric, Classifi- cation of 14 Sources, Electric, Electro- motive Force of 14, 15 Sparking at Dynamo Brush- es, Cause of 147, 148 294 INDEX. Specific Magnetic Resis- tance 97 Specific Resistance, Defini- tion of 18 Speed and Torque, Classi- fication of, in Motors. ... 171 Speed of Motor, Varied by Inserting Resistance in Armature Circuit. . . .177, 178 Speed of Motor, Varied by Varying Magneto-motive Force of Field Magnets.. 178, 179 Standard Candle 205 Standard Cell, Clark. ..15, 16 Standard Megohm 30 Standard of Physiologically Effective Luminous Radi ation 205 Standard Resistance — 29, 30 Star Triphase Winding, Diagram of 267 Star- Winding of Triphase Generator 267 Step-Down Transformer. 273 Step-Up Transformer 273 Strain, Displacement ...9, 10 Street-Car Motors 191 Stress, Electromotive, Cause of 2 Stresses and Strains in Ether i, 2 Structural Magnetomotive Force 93 Sun, Total Amount of Energy in 7 Surface, Contact Resis- tance 39 Table of Electro-Chemical Equivalents 74 Table of Resistivities — 19, 20 Table of Thermal Resis- tivities 196 Temperature Coefficients for Clark Standard Cell. 16 Temperature Coefficients for Resistivity 19, 20 Temperature, Effect of, on Efficiency of Lamp 207 Temperature, Effect of, on Life of Lamp 207 Temperature, Effect of, on Luminous Radiation. 204 Temperature, Effect of, on Resistivity of Conductors 26 Temperature, Safe Limit- ing, of Wire 198, 199 Terminal, Negative , o f Voltaic Cell 66 Terminal, Positive, of Voltaic Cell 66 Thales i Therm 192 Therm-Calorie... 193 Thermal Conductivity 194 Thermal Resistivities, Table of 196 Thermal Resistivity. 194, 195 Thomson's High Grade Mirror Galvanometer. 47, 48 Thomson's Marine Galvano- meter 46 Thomson's Mirror Galvano- meter 46 Three-Wire System, Cal- culation of Current Strength in 55, 56 INDEX 295 Three Wire System, De- scription of 54, 55 Three- Wire System, Neutral Wire in 55 Toothed Core Motor- Arma- ture 185 Torque and Speed, Classifi- cation of, in Motors.. 171 Torque and Speed, Rela- tion of, to Activity of Motor. 171 Torque of Motor 167 Trailing Pole of Motor- Armature. 186 Transformation, Ratio of 273. 274 Transformer, Step-Down. 273 Transformer, Step-Up 273 Transient Magnetomotive Force 91 Tregohm, Definition of .. 18 Triangular Triphase Wind- ing Diagram of 267 Triangular Winding of Tri- phase Generator 267 Tricrohm, Definition of.... 18 Triphase Circuit, Analysis of 270 Triphase E. M. F'S 267 Triphase E. M. F.'S, Diagram of 268 Triphase Generator, Star- Winding of 267 Triphase Generator, Wind- ing of 267 Triphase Generators, Tri- angular-Winding of 267 Unit Arc-Light Crater In- tensity 223 Unit of Activity, c. G. s 7 Unit of Flux, Density of. 90 Unit of Force, c. G. s 5 Unit of Heat 192 Unit of Illumination, Name Proposed for 206 Unit of M. M. F 92 Unit of Quantity, c. G. s. Wheatstone's Bridge, Vari- ous Forms of 28, 29 Winding, Combination Tri- phase . . 268 Wire, Formula for Calcula- ting Size of, Required to Fill Given Bobbin. 37, 38, 39 Wires , Limiting Current Strength in 198, 199 -Work, Absorbed by Mo- tor 170 Work, Definition of 3 Work Unit of... 6 ERRATA. Page 23, If 23, 5 lines from bottom of page. For resistivity of a mile read resistance of a mile. ^ " 24, Syllabus, 9th line. For begohm read bicrohm. - 34, 1[ 34. For R = rapp. coth-i \/ ^ <, -ttapp. read R = \/R&pv. rapp. /tanbr ' 34, last line. For coth V; 2656 read 1 / tanh -iA/2656 V R(Y).A 6024 " K 6024 " 175, If 182. For reluctance read retardation. ~* " 203, " 211. For yellow read green. -S " 230, Fig. 77, caption. For Magnetic read Mangin. 44 258, If 261. For n—\ read n + 1. - " 264, Syllabus. For n— 1 read n + 1. J OT THB UJIVEBSITT ill. 