Hz (in which "M" symbolizes mega, or million). In 1891, an Irish-Italian, Guglielmo Marconi, began experimenting with the newly discovered potential of Hertzian waves. He proceeded to explore aerials (antennas), and proved the importance of a grounded connection to a wireless transmission system. The same year, Frenchman Edouard Branly perfected an apparatus for intercepting wireless impulses. The device intercepted Hertzian waves in the air and caused them to ring an electric bell. A Brit, Sir William Crookes, proved the theoretical feasibility of "telegraphy through space" in an article published in the Fortnightly Review. In 1895, Thomas Edison patented a system of induction telegraphy that included elements that later advanced wireless communications. In 1831, Michael Faraday (another Englishman) discovered induction by showing that a current in one wire could produce a current in another wire. The History and Technology of Analog Video 1 second 1 cycle per second (1 Hz) 2 cycles per second (2 Hz) 3 cycles per second (3 Hz) 1 cycle Figure 5-1. Sine Wave (Michel Bayard) Finally, in 1895, Marconi amalgamated all the principles just mentioned, added some of his own science and applied for the first patent for a wireless telegraph. It became the basis for his Marconi Wireless Telegraph Company, the world's first commercial radio service. In 1901, Marconi was able to receive the three dots of the letter "S" in a transoceanic broadcast between England's Cornwall coast and Canada's Newfoundland. In 1907, he established the first regular commercial transatlantic wireless telegraph service. In 1901, Dr. Reginald Aubrey Fessenden, a professor at Pittsburgh's Weston University, took another huge stride forward when he transmitted and received the human voice without wires. Fessenden, instead of interrupting a wireless wave with signal bursts, altered the inherent characteristics of a sine wave (in this case, its amplitude), by superimposing another signal over it. The carrier or sideband, over which the second signal tr