Replica of Hertz oscillator with rectangular plates 40 x 140 cm, made by Modellbauanstalt Munchen, Munich, 1928-1929. Original Hertz apparatus in Deutsches Museum

In 1873, a Scottish mathematician and physicist, James Clerk Maxwell, proposed a theory that electromagnetic waves would behave in much the same way as light beams, and thus could be controlled. Hertz's experiments in 1887 were trying to prove this theory. He used the oscillator to generate sparks, which, if the theory was correct, would be received by a loop. When he switched on the oscillator, the sparks were received, proving Maxwell's theory correct. This provided the scientific foundations for wireless telegraphy.