The Radio Amateur's Hand Book / A Complete, Authentic and Informative Work on Wireless Telegraphy and Telephony

THE RADIO AMATEUR'S HAND BOOK
A Complete, Authentic and Informative Work on Wireless Telegraphy and Telephony
BY FREDERICK COLLINS
Inventor of the Wireless Telephone 1899; Historian of Wireless 1901-1910; Author of Wireless Telegraphy 1905
1922
TO WILLIAM MARCONI INVENTOR OF THE WIRELESS TELEGRAPH
Before delving into the mysteries of receiving and sending messages without wires, a word as to the history of the art and its present day applications may be of service. While popular interest in the subject has gone forward by leaps and bounds within the last two or three years, it has been a matter of scientific experiment for more than a quarter of a century.
The wireless telegraph was invented by William Marconi, at Bologna, Italy, in 1896, and in his first experiments he sent dot and dash signals to a distance of 200 or 300 feet. The wireless telephone was invented by the author of this book at Narberth, Penn., in 1899, and in his first experiments the human voice was transmitted to a distance of three blocks.
The first vital experiments that led up to the invention of the wireless telegraph were made by Heinrich Hertz, of Germany, in 1888 when he showed that the spark of an induction coil set up electric oscillations in an open circuit, and that the energy of these waves was, in turn, sent out in the form of electric waves. He also showed how they could be received at a distance by means of a ring detector, which he called a resonator .
In 1890, Edward Branly, of France, showed that metal filings in a tube cohered when electric waves acted on them, and this device he termed a radio conductor ; this was improved upon by Sir Oliver Lodge, who called it a coherer. In 1895, Alexander Popoff, of Russia, constructed a receiving set for the study of atmospheric electricity, and this arrangement was the earliest on record of the use of a detector connected with an aerial and the earth.
Marconi was the first to connect an aerial to one side of a spark gap and a ground to the other side of it. He used an induction coil to energize the spark gap, and a telegraph key in the primary circuit to break up the current into signals. Adding a Morse register, which printed the dot and dash messages on a tape, to the Popoff receptor he produced the first system for sending and receiving wireless telegraph messages.