rvice 310
local service 316
meter method 316
prepayment method 318
ticket method 316
rates 310
toll service 311
long haul 311
short haul 311
timing toll connections 312
units of charging 311

Mechanical signals 27
Kellogg 28
Monarch 28
Western Electric 27

Mercury-arc rectifier circuits 237

Monarch visual signal 28

Multi-office exchanges, necessity for 109

Multiple switchboard 43
busy test 48
cord circuits 46
diagram showing principle of 47
double connections 46
field of each operator 51
field of utility 43
influence of traffic 52
line signals 45
multiple feature 43

P

Phantom circuit 321

Pilot signals 17

Plug-seat switch 38

Pole changers for harmonic ringing 231

Power plants 227
auxiliary signaling currents 233
currents employed 227
alternating current 227
direct current 227
operator's transmitter supply 228
power plant circuit 248
power switchboard 246
meters 246
protective devices 248
switches 246
primary sources 234
charging from direct-current mains 234
charging dynamos 235
mercury-arc rectifiers 236
rotary converters 234
provision against breakdown 237
capacity of power units 238
duplicate charging machines 238
duplicate primary sources 238
duplicate ringing machines 238
ringing-current supply 229
magneto generators 229
pole changers 229
ringing dynamos 232
storage battery 239
initial charge 241
installation 240
low cells 244
operation 242
overcharge 243
pilot cell 243
regular charge 244
replacing batteries 245
sediment 245
types 227
common-battery systems 228
magneto systems 228

Power switchboard 246

Private-branch exchanges 271
with automatic offices 278
secrecy 279
battery supply 279
circuits, key-type board 276
definitions 271
desirable features 281
functions of the private-branch exchange operator 272
marking of apparatus 281
private-branch switchboards 273
common-battery type 273
cord type 275
key type 275
magneto type 273
ringing current 280
supervision of private-branch connections 277

R

Relays 28

Rotary connector 202

S

Selecting switches 175

Selector 175

Simplex circuits 324

Storage battery 239

Storage cell 240

Stromberg-Carlson multiple board 96

Strowger automatic system 143