e, 68, 74;
effect of B-battery upon, 128;
how to plot a, 70

Characteristic curve of transformer, 64

Chemistry, 8

Choke coils, 210, 221

Circuit, A, B, C, 187;
coupled, 115;
defined, 43;
oscillating, 113;
plate, 45;
short, 30;
tune of a, 117

Condenser, defined, 77;
charging current of, 78;
discharge current of, 80;
impedance of, 135;
theory of, 78;
tuning, 224

Common battery system, 254

Connection for wire to radio, 254

Continuous waves, 86

Copper, atomic number of, 13

Copper sulphate, in solution, 21

Crystals, atomic structure, 147

Crystal detectors, 146;
characteristic of, 148;
circuit of, 150;
theory of, 147

Current, transient, 114;
radio, 144

Cycle, 94, 97

Damped oscillations, 114

Demodulation, 231

Detection, explained, 146

Detectors, audion, 126;
crystal, 146

Direct currents, 205

Dissociation, 22

Distortion, of wave form, 163

Dry battery, 27

Earth, atomic constitution, 11

Effective value, of ampere, 207;
of volt, 207

Efficiency, of regenerative circuit, 182

Electrical charge, 22

Electricity, current of, 15, 16

Electrodes, of vacuum tube, 41;
definition of, 41

Electrolyte, definition of, 34

Electrons, properties of, 4;
planetary, 10, 12;
rate of flow, 48;
vapor of, 39;
wandering of, 14

Electron streams, laws of attraction, 200

E. M. F., 59;
alternating, 76;
of self-induction, 238

Energy, expended in tube, 235;
of electrons, 113;
radiation of, 125

Ether, 88

Feed-back circuit, 182

Frequency, 98, 158;
effect upon pitch, 133;
interval, 247;
natural, 117;
of voice, 163

Fundamental note, of string, 157

Gravity battery, theory of, 23

Grid, action of, 47;
condenser, 169;
current, 173;
leak, 171;
leak, construction, 172, 216;
of audion, 41

Harmonics, 160

Helium, properties of, 9

Henry, 83

Heterodyne, 181

Hot-wire ammeter, 51

Human voice, mechanism of, 152

Hydrogen, action of in acid, 7;
atom of, 7

Impedance, of coil, 136;
of condenser, 136;
of transformer, 195;