248 



Telephone: 



limit of transmission, 153. 

 central station, 164. 

 affected by heat-lightning, 183. 

 Telephote, 17.3. 

 Thales of Miletus first described electrical prop 



erties of amber. C>. 

 Theophrastus mentions amber, 6. 

 Thermo-electric pile, 75. 

 Torpedo, the, 6. 

 Tni informers at Niagara, 200. 

 Transmission, multiple, ( h. XIII, 114. 

 Trow bridge, Prof., telephones through the earth 



183. 



Tunnel at Niagara, !!>. 

 Tyndall, and Gray's experiments, 92. 



Unrest of the universe, 38. 



Volt, unit of electrical pressure, 85. 

 Volta, Alessandro, and the voltaic pile, 13. 



Watt, James, 86. 



unit of electrical power, 86. 

 Way duplex system, Ch. XIV, 129. 

 Wheatstone transmits musical tones mechani 

 cally, 92. 



needle telegraph, 108. 



dial-telegraph, 159. 

 Wireless telegraphy, Ch. XXI, 176. 



signaling by ether-waves, 176. 



Morse and Henry, 177. 



Trowbridge, Dolbear, Hertz, 178. 



Branly, Marconi, 179. 



Marconi's system, 180. 



by earth-currents, 182. 

 \Yolimer, King of Goths, a natural battery, 7. 



