5 i6 



INDEX. 



Railway motors, characteristics of, 415 

 Rating of arc lamps, 337 



of generators, 82 

 Ratings and guarantees, 145 

 standard, 164 



estimation of, from speed and dimen- 

 sions, 148, 165 



of dynamos, 169 

 Reaction, armature, 151 

 Reentrancy of an armature winding, 428 

 Regulation, voltage, as a factor in wiring, 

 28 S 



of generators, 88 

 Reluctance, magnetic, 368 

 Reluctivity, 369 



Residual magnetism, definition of, 361 

 Resistance, definition of, 20 



of brush contacts, 472-473 



temperature coefficient of, 21 

 Resistances and weights of copper wire, 



306 



Resistivity, see specific resistance. 

 Return-loop wiring scheme, 292 

 Rheostat, starting, the, 112 

 Ring armature, the, 418 



Safety, personal, rules for, 133 

 Series connections, 24 



generator and motor compared, 96 

 connections of, 78 

 the, 46 



grouping of glow lamps, 266 

 motor, the, 118 

 parallel controller, 121 

 system of distribution, 266 

 Shades, lamp, 338 

 Shunt booster, the, 257 



generator and motor compared, 95 

 connections of, 79 

 the, 45 

 motor, 101 



speed control of, 105 



regulation of, 104 

 starting, 1 12 



Siemens' law of efficiency of a motor, 99 

 Sign, algebraic, of magnet pole, 3 

 Simplex armature winding, 429 



Size of wires for electric distribution, 275 

 Solenoid, definition of, 19 

 Sparking of dynamos, 151 



conditions of, 161 

 Specific gravity (see density). 



resistance, 21 

 Spectro-photometry, 309 

 Speed control of motors, comparison of 



methods, 109 

 of shunt motor, 105 

 regulation of shunt motor, 104 

 Speeds of dynamos, 145 

 Standard lamps, 310 



ratings and guarantees, 164 

 Starting a generator or motor, method 



of, 174 



of shunt motor, 1 12 

 rheostat, the, 112 

 Steam power, cost of, 221 

 Steel and iron wire, weights and resis- 

 tances of, 307 

 magnetic properties of, 365 

 Storage batteries, management and care 



of, 250 

 use of, 254 



weights and costs, 250 

 battery, action of, 242-247 

 grids, 247 

 the, 242 

 cell, the, 242 

 Stray power loss in generators and 



motors, 129, 130 

 Street lighting, 325 



Table of armature-winding conditions, 



436 

 candle-power and efficiency of glow 



lamps, 344 



carrying capacities, 284 

 costs of installation, 230 



of operation, 231 

 density of wires, 283 

 hysteretic coefficients, 380 

 magnetic properties of iron and 



steel, 365 

 resistances and weights of copper 



wires, 306 



