Volume 1 — INDEX

ToC

INDEX

A

Acousticon transmitter 77 Acoustics 19 characteristics of sound 19 loudness 20 pitch 20 timbre 21 human ear 23 human voice 22 propagation of sound 19 Air-gap vs. fuse arresters 304 Amalgamated zincs 97 Arrester separators 296 Audible signals 39 magneto bell 40 telegraph sounder 39 telephone receiver 43 vibrating bell 40 Automatic Electric Company direct-current receiver 85 transmitter 72 Automatic shunt 124

B

Bar electromagnet 148 Battery bell 115 Battery symbols 114 Blake single electrode 64 Brazed bell 130 Broken-back ringer 280 Broken-line method of selective signaling 261, 275

C

Capacity reactance 55 Carbon 31 adaptability 31 limitations 33 preparation of 75 superiority 32 Carbon air-gap arrester 300 Carbon-block arrester 296 Carrying capacity of transmitter 76 Central-office protectors 310 Characteristics of sound 19 loudness 20 pitch 20 timbre 21 Chloride of silver cell 113 Closed-circuit cells 106 Closed-circuit impedance coil 164 Common-battery telephone sets 217 Condensers 178 capacity 178 charge 178 conventional symbols 184 definition of 180 dielectric 180 dielectric materials 182 functions 184 means for assorting current 185 sizes 183 theory 179 Conductivity of conductors 49 Conductors, conductivity of 49 Conventional symbols 91 Cook air-gap arrester 298 arrester 311 arrester for magneto stations 313 Crowfoot cell 106 Current supply to transmitters 186 common battery 188 advantages 188 bell substation arrangement 192 bridging battery with impedance coils 194 bridging battery with repeating coil 191 current supply from distant point 204 current supply over limbs of line in parallel 200 Dean substation arrangement 197 double battery with impedance coil 195 Kellogg substation arrangement 198 North Electric Company system 199 series battery 189 series substation arrangement 190 Stromberg-Carlson system 198 supply many lines from common source 202 repeating coil 202 retardation coil 204 local battery 187

D

Dean drop and jack 344 receiver 88 wall telephone hook 137 Desk stand hooks 138 Kellogg 140 Western Electric 138 Dielectric 180 Dielectric materials 182 dry paper 182 mica 182 Differential electromagnet 151 Direct-current receiver 84 Drainage coils 315

E

Electric lamp signal 44 Electrical hazards 287 Electrical reproduction of speech 24 carbon 31 conversion from sound waves to vibration of diaphragm 21 conversion from vibration to voice currents 24 conversion from voice currents to vibration 25 cycle of conversion 26 detrimental effects of capacity 36 early conceptions 28 electrostatic telephone 30 induction coil 34 limitations of magneto transmitter 29 loose contact principle 27 magneto telephone 26 measurements of telephone currents 36 variation of electrical pressure 30 variation of resistance 30 Electrical signals 39 audible 39 magneto-bell 40 telegraph sounder 39 telephone receiver 43 vibrating bell 40 visible 43 electric lamp signal 44 electromagnetic signal 43 Electrodes 75 arrangement of 63 carbon preparation 75 multiple 65 single 64 Electrolysis 315 Electromagnetic method of measuring telephone currents 37 Electromagnetic signal 43 Electromagnets and inductive coils 143, 171 conventional symbols 171 differential electromagnet 151 direction of armature motion 151 direction of lines of force 146 electromagnets 143 low-resistance circuits 147 horseshoe form 147 iron-clad form 149 special horseshoe form 150 impedance coils 163 kind of iron 164 number of turns 103 types closed-circuit 164 open-circuit 164 toroidal 165 induction coil 165 current and voltage ratios 166 design 166 functions 166 use and advantage 167 magnet wire 153 enamel 156 silk and cotton insulation 155 space utilization 156 wire gauges 154 magnetic flux 144 magnetization curves 145 magnetizing force 143 mechanical details 152 permeability 144 reluctance 147 repeating coil 168 winding methods 158 winding calculations 162 winding data 159 winding terminals 159 Electrostatic capacity 50 unit of 52 Electrostatic telephone 30 Enamel 156

F

Five-bar generator 123 Fuller cell 109

G

Galvani 92 Generator armature 119 Generator cut-in switch 125 Generator shunt switch 124 Generator symbols 127 Granular carbon 66 Gravity cell 106

H

Hand receivers 90 Harmonic method of selective signaling 248 advantages 258 circuits 257 in-tune system 253 limitations 258 principles 248 tuning 250 under-tune system 250 Head receivers 90 Heat coil 306 Holtzer-Cabot arrester 300 Hook switch 132 automatic operation 133 contact material 135 design 134 desk stand hooks 138 Kellogg 140 Western Electric 138 purpose 132 symbols 141 wall telephone hooks 135 Dean 137 Kellogg 135 Western Electric 136 Horseshoe electromagnet 148 Human ear 23 Human voice 22

I

Impedance coils 163 kind of iron 164 number of turns 163 symbols of 165 types closed-circuit 164 open-circuit 164 toroidal 165 Inductance vs. capacity 56 Induction coil 34, 165 current and voltage ratios 166 design 166 functions 166 use and advantage 167 Inductive neutrality 174 Inductive reactance 55 Insulation of conductors 56 Introduction to telephony 11 Iron-clad electromagnet 149 Iron wire ballast 177

K

Kellogg air-gap arrester 299 desk stand hook 140 drop and jack 342 receiver 83 ringer 129 transmitter 70 wall telephone hook 135

L

Lalande cell 112 Lamp filament 176 Le Clanché cell 99 Lenz law 54 Line signals 325 Lines of force, direction of 146 Loading coils 59 Lock-out party-line systems 263 broken-line method 275 operation 282 Poole system 264 step-by-step system 267 Loudness of sound 20 Low-reluctance circuits 147 horseshoe form 147 iron-clad form 149

M

Magnetic flux 144 Magnetization curves 145 Magnetizing force 143 Magneto bell 40, 115 Magneto operator 116 Magneto signaling apparatus 115 armature 119 automatic shunt 124 battery bell 115 generator symbols 127 magneto bell 115 magneto generator 116 method of signaling 115 polarized ringer 128 pulsating current 126 ringer symbols 131 theory 117 Magneto switchboard 324 automatic restoration 341 mechanical 341 Dean type 344 Kellogg type 342 Monarch type 345 Western Electric type 313 circuits of complete switchboard 356 code signaling 346 commercial types of drops and jacks 335 early drops 335 jack mounting 338 manual vs. automatic restoration 340 methods of associating 339 night alarm 338 tubular drops 336 component parts 325 jacks and plugs 325 keys 327 line and cord equipments 328 line signal 325 operators' equipment 328 cord-circuit considerations 364 double clearing-out type 368 lamp-signal type 371 non-ring through type 366 series drop type 366 simple bridging drop type 364 definitions 324 electrical restoration 347 grounded and metallic-circuit lines 360 mode of operation 324 night-alarm circuits 358 operation in detail 328 clearing out 335 essentials of operation 335 normal condition of line 329 operator answering 330 operator calling 332 subscriber calling 330 subscribers conversing 333 operator's telephone equipment 354 cut-in jack 355 ringing and listening keys 351 horizontal spring type 351 party-line ringing keys 353 self-indicating keys 354 vertical spring type 352 switchboard assembly 373 functions of cabinet 373 sectional switchboards 384 upright type of switchboard 376 wall type switchboard 373 switchboard cords 349 concentric conductors 350 parallel tinsel conductors 351 steel spiral conductors 350 switchboard plugs 348 Magneto telephone 26 Magneto telephone sets 209 Mica card resistance 174 Mica slip fuse 302 Microtelephone set 223 Monarch drop and jack 345 Monarch receiver 86 Monarch transmitter 73 Multiple electrode 65 Mutual induction 54

N

Non-inductive resistance devices 172 inductive neutrality 174 provisions against heating 174 temperature coefficient 172 types differentially-wound unit 175 iron wire ballast 177 lamp filament 176 mica card unit 174 Non-selective party-line systems 227 bridging 230 limitations 235 series 229 signal code 233

O

Open-circuit cells 99 Open-circuit impedance coil 164 Operator's receiver 90

P

Packing of transmitters 75 Permeability 144 Pitch 20 Doppler's principle 20 vibration of diaphragms 21 Polarity method of selective signaling 239 Polarization of cells 96 Polarized ringer 41, 128 brazed bell 130 Kellogg 129 Western Electric 128 Poole lock-out system 264 Primary cells 92 conventional symbol 114 series and multiple connections 98 simple voltaic 92 types of closed-circuit 106 Fuller 109 gravity 106 Lalande 112 prevention of creeping 106 setting up 108 open-circuit 99 Le Clanché 99 standard 113 chloride of silver 113 Propagation of sound 19 Protective means 294 against high potentials 294 air-gap arrester 295 advantages of carbon 296 commercial types 297 continuous arcs 300 discharge across gaps 295 dust between carbons 296 introduction of impedance 299 metallic electrodes 300 vacuum arresters 299 against sneak currents 304 heat coil 306 sneak-current arresters 305 against strong currents 301 fuses 301 enclosed 302 mica 301 proper functions 301 central-office protectors 310 self-soldering heat coils 310 sneak-current and air-gap arrester 310 city exchange requirements 314 complete line protection 306 electrolysis 315 subscribers' station protectors 312 ribbon fuses 313 Pulsating-current commutator 127

R

Receivers 80 Dean 88 direct-current 84 early 80 Kellogg 83 modern 81 Monarch 86 operator's 90 single-pole 81 symbols 91 Western Electric 82 Reluctance 147 Repeating coil 168 Ribbon fuses 313 Ringer symbols 131 Ringing and listening key 327 Robert's latching relay 276 Robert's self-cleansing arrester 297 Rolled condenser 182

S

Saw-tooth arrester 296 Selective party-line systems 238 broken-line method 261 classification broken-line systems 239 harmonic systems 238 polarity systems 238 step-by-step systems 239 harmonic method 248 polarity method 239 step-by-step method 259 Self-induction 54 Signal code 235 Signaling, method of 115 Silk and cotton insulation 155 Single electrode 64 Single-pole receiver 81 Sneak-current arresters 305 Solid-back transmitter 66 Sound characteristics of 19 loudness 20 pitch 20 timbre 21 Standard cell 113 Step-by-step lock-out system 67 Step-by-step method of selective signaling 259 Subscribers' station protectors 312 Switchboard cords 349 Switchboard plugs 348 Switchboard transmitter 79 Symbols battery 114 condenser 184 generator 127 hook switch 141 impedance coil 165 induction coil 171 receiver 91 repeating coil 171 ringer 131 ringing and listening key 327 transmitter 79

T

Table condenser data 184 copper wire 151 German silver wire — 18 per cent 174 German silver wire — 30 per cent 175 metals, behavior of, in different electrolysis 95 signal code 235 specific inductive capacities 181 temperature coefficients 172 transmission distances, limiting 57 winding data for insulating wires 160 Tandem differential electromagnet 152 Telegraph sounder 30 Telephone currents, measurements of 36 electromagnetic method 37 thermal method 37 Telephone exchange, features of 317 districts 318 subscribers' lines 318 switchboards 319 toll lines 318 trunk lines 318 Telephone lines 47 conductivity of conductors 49 electrostatic capacity 50 inductance of circuit 54 inductance vs. capacity 56 insulation of conductors 56 transmission 60 Telephone sets 207 classification of 208 common-battery telephone 208 magneto telephone 208 wall and desk telephones 208 common-battery 217 desk 220 hotel 219 wall 219 magneto 209 circuits of bridging 215 series 212 desk 211 wall 209 Temperature coefficients 172 Thermal method of measuring telephone currents 37 Timbre 21 Toroidal impedance coil 165 Toroidal repeating coil 170 Transmission, ways of improving 60 Transmitters 63 acousticon 77 Automatic Electric Company 72 carrying capacity 76 conventional diagram 79 electrode 75 arrangement of 63 multiple 65 single 64 granular carbon 66 Kellogg 70 materials 63 Monarch 73 packing 75 sensitiveness 77 switchboard 79 symbols 79 variable resistance 63 Western Electric solid-back 66

U

Under-tuned ringer 252

V

Vacuum arrester 299 Variable resistance 63 Vibrating bell 40 Visible signals 43 electric lamp 44 electromagnetic 43 Volta 92 Voltaic cell 92 amalgamated zincs 97 difference of potential 94 local action 96 polarization 96 theory 93

W

Wall telephone hooks 135 Dean 137 Kellogg 135 Western Electric 136 Western Electric air-gap arrester 298 desk stand hook 138 drop and jack 343 receiver 82 ringer 128 solid-back transmitter 66 station arrester 313 wall telephone hook 136 White transmitter 66 Wire gauges 154