The scientific groundwork for radio and television was laid by the Scottish physicist James Clerk Maxwell, who in 1864 theorized that changes in electrical and magnetic forces send waves spreading through space at 186,000 miles per second. Light consists of such waves, Maxwell said, adding that others might exist at different frequencies. In 1888 a German scientist named Heinrich Hertz confirmed Maxwell's surmise with an apparatus that used sparks to produce an oscillating electric current; the current, in turn, generated electromagnetic energy that caused matching sparks to leap across a gap in a receiving loop of wire a few yards away. And in 1900 brilliant inventor Nikola Tesla was granted two patents for basic radio concepts and devices that inspired others after him.
Fascinated by such findings, Guglielmo Marconi, son of an Irish heiress and Italian aristocrat, began experimenting with electricity as a teenager and soon was in hot pursuit of what he called "wireless telegraphy." In the system he developed, Hertzian sparks created the electromagnetic waves, but Marconi greatly extended their effective range by electrically grounding the transmitter and aerial. At the heart of his receiver was a device called a coherer—a bulb containing iron filings that lost electrical resistance when hit by high-frequency waves. The bulb had to be tapped to separate the filings and restore sensitivity after each pulse was received.
As evidenced by his America's Cup feat in 1899, Marconi was a master of promotion. In 1901 he gained worldwide attention by transmitting the letter "s"—three Morse pips—across the Atlantic. Although his equipment didn't work well over land, he built a successful business by selling wireless telegraphy to shipping companies, maritime insurers, and the world's navies. Telegraphy remained his focus. He didn't see a market beyond point-to-point communication.