Scientific Research Applied to the Telephone Transmitter and Receiver

Scientific Research Applied to the Telephone Transmitter and Receiver * By EDWIN H. COLPITTS ET US recall a scene at the Centennial Exhibition in Philadelphia in 1876. Across a room had been strung wires connecting crude instruments, at one end of the room a transmitter and at the other end of the room a receiver. Dom Pedro, Emperor of Brazil, takes up the receiver and listens while Alexander Graham Bell speaks into the transmitter. The Emperor, astonished at hearing Mr. Bell's voice in the receiver, exclaims in amazement, " M y God, it talks." When at the same place, Sir William Thomson (later Lord Kelvin) took up the receiver and listened to Mr. Bell, the words of this distinguished scientist were, " I t does speak," and continuing, " i t is the most wonderful thing I have seen in America." Sixty years have passed and, as a result of continued effort, the use of the telephone has become such an everyday matter that even the ability to talk from Tokyo in your country to New York in my country scarcely excites comment or wonder. It is not surprising that, to the layman, the element of distance seems the most striking factor in the technical development of the telephone art. As a matter of fact, while the conquest of distance has involved much scientific effort, and very ingenious and highly developed methods for the transmission of speech currents, the magic of the telephone still resides in the instruments which provide for the conversion of mechanical energy, namely speech sounds of highly complex wave form, into electrical currents of corresponding wave form, and the reverse process of converting these electrical currents into speech sounds.