Left, keeps reversing the current--Sounding instruments--Telegraphic relays--Recording telegraphs--High-speed telegraphy 127 Chapter VII.--WIRELESS TELEGRAPHY. The transmitting apparatus--The receiving apparatus--Syntonic transmission--The advance of wireless messages, 143. Talking-machines, 310. Tapper in wireless telegraphy 137 Chapter VIII.--THE TELEPHONE. The Bell telephone--The Edison transmitter--The granular carbon transmitter--General arrangement of electric.