Wireless Telegraphy and Telephony

LIST OF ILLUSTRATIONS XV PAGE Fig. 124.—Method of registering vibrations of a tuning fork 109 Fig. 125.—Way line made by a bristle attached to a tuning fork prong in vibration when passed over smoked glass 109 Fig. 126.—Illustrating the action of air waves . . . . no Fig. 127 .—The vocal chords in position for making a sound no Fig, 128.—The vocal chords when relaxed . . . . m Fig. 129 .—Koenig’s manometric flame apparatus . . . in Fig. 130 .—Appearance of manometric flame in revolving mirror ..............................................112 Fig. 131 .—Diagram of a telephone transmitter . . . 115 Fig. 132 .—Diagram showing the principle and construction of the telephone receiver...............................115 Fig- T33-—The photophone.................................116 Fig. 134 .—Photophone receiving apparatus . . . . 117 F'g- I35-—Photophone transmitting apparatus . . . 118 Fig. 136 .—Powerful searchlight arranged to transmit speech over a beam of light.................................120 Fig. 137 .—The electric arc..............................121 Fig, 138.—Circuit showing how a singing arc is arranged . 122 Fig. 139 .—A logical form of wireless telephone which is im- practical ...........................................125 Fig. 140 .—DeForest wireless telephone equipment . . . 126 Fig. 141 .—Wireless telephone receiving apparatus (induction method)..............................................127 Fig. 142 .—Fessenden wireless telephone transmitting phono- graph music..........................................128 Fig. 143 .—Diagram illustrating why damped oscillations will not carry the voice ........ 129 Fig. 144 .—How the sound waves of the voice are impressed upon undamped oscillations . . . . . 13° Fig, 145.—Arrangement of the speaking arc .... 131 Fig. 146 .—Diagram showing how a wireless telephone trans- m itting system is arranged........................I31 Fig. 147 .—Poulsen wireless telephone equipment . . . 132 Fig. 148.—The Majorana wireless telephone transmitter . 133 Fig. 149 .—Showing the brush discharge from a Marconi trans- atlantic aerial at night.............................135 Fig. 150 .—An amateur wireless telegraph station . . . 138 Fig. 151 .—The high-power naval wireless telegraph station un- der construction at Washington, D. C. . . • 139