Another important component of Tesla's Long Island apparatus was an underground array of iron pipes which extended outward from the bottom of a deep shaft beneath the transmitter tower. When coupled with the transmitter these pipes provided a connection to the earth through which a powerful oscillating electrical current would flow. Unlike a conventional radio transmitter with an antenna that radiates dissipating electromagnetic waves out into space, the magnifying transmitter's extra coil excites a low-frequency ground wave called the Zenneck surface wave. In this case the propagating energy does not radiate into space but is concentrated near the earth's surface.
The \"Tesla Central Power Plant\", was a 200 by 200-foot brick building. It contained an office, library, a complete machine shop, an instrument room and a display room filled with many of his most prized inventions.9 The most important reason for this building was the electrical equipment. It housed a steam boiler, turbine and a generator along with other sophisticated electrical apparatus to manipulate and regulate electrical current. The current that was to be used by the magnifying transmitter which was to be located in the Transmitting Tower for World Telegraphy. 781b155fdc