112

14 Why and How to Use a Detector 124

15 Radio-Telephony 140

16 The Human Voice 152

17 Grid Batteries and Grid Condensers for
Detectors 165

18 Amplifiers and the Regenerative Circuit 176

19 The Audion Amplifier and Its Connections 187

20 Telephone Receivers and Other
Electromagnetic Devices 199

21 Your Receiving Set and How to Experiment 211

22 High-Powered Radio-Telephone
Transmitters 230

23 Amplification at Intermediate
Frequencies 242

24 By Wire and by Radio 251

Index 263

LIST OF PLATES

I One of the Lines of Towers at Radio Central
Frontispiece

II Bird's-Eye View of Radio Central 10

III Dry Battery for Use in Audion Circuits,
and also Storage Battery 27

IV Radiotron 42

V Variometer and Variable Condenser of
the General Radio Company. Voltmeter
and Ammeter of the Weston Instrument
Company 91

VI Low-Power Transmitting Tube, U V 202 106

VII Photographs of Vibrating Strings 155

VIII To Illustrate the Mechanism for the
Production of the Human Voice 170

IX Western Electric Loud Speaking
Receiver. Crystal Detector Set of the
General Electric Co. Audibility Meter
of General Radio Co. 203

X Audio-Frequency Transformer and
Banked-Wound Coil 218

XI Broadcasting Equipment, Developed by
the American Telephone and Telegraph
Company and the Western Electric Company 235

XII Broadcasting Station of the American
Telephone and Telegraph Company on the
Roof of the Walker-Lispenard Bldg. in
New York City where the Long-distance
Telephone Lines Terminate 250

LETTER