CONTENTS
LETTER		PAGE
1	Electricity and Matter	3
2	Why a Copper Wire Will Conduct Electricity	9
3	How a Battery Works	16
4	The Batteries in Your Radio Set	27
5	Getting Electrons from a Heated Wire	34
6	The Audion	40
7	How to Measure an Electron Stream	48
8	Electron-Moving-Forces	57
9	The Audion-Characteristic	66
10	Condensers and Coils	77
11	A “C-W” Transmitter	86
12	Inductance and Capacity	96
13	Tuning	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

LETTERS OF A RADIO-ENGINEER TO HIS SON

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