That light is electric waves in the ether has been known for the last couple of hundred years and later on scientific sharks believed there were other and longer electric waves but they didn’t know how to produce them or to receive them until 1888. In that year Heinrich Hertz, a young German college professor, discovered that when an electric spark was made by any kind of an apparatus the positive and negative electric charges in uniting together would not only break down the air to make the spark, but would form an _oscillating current_, that is, a current which surges to and fro hundreds of thousands of times a second, and that this _high frequency current_, as it is called, sets up waves in the ether just as the vibrations of a bell set up waves in the air. Hertz made an apparatus by which he could produce electric waves of different lengths and this he called an _oscillator_. It consisted of a couple of wires fixed to the balls of the spark-gap of an induction coil, on the other and free end of which were soldered a couple of sheets of copper. (See the accompanying picture.) [Illustration: Hertz’s oscillator] He also devised a simple apparatus to detect the presence of these waves--that is, to receive them, which he called a _resonator_, and this was a cut wire ring with a little brass ball on each of its ends as shown in the following diagram. Now when Hertz set his induction coil going, streams of sparks were set up in the spark-gap of the oscillator and _electric oscillations_, or high-frequency currents, surged from one of the copper plates to the other and back again, and these sent out trains of electric waves through the ether. [Illustration: Hertz’s detector] By holding his resonator, or as we would call it now, his _detector_, at a little distance from his sending apparatus, when the latter sent out the electric waves they would set up electric oscillations, or currents of high frequency, in the ring detector and these in turn would make a stream of little sparks jump across the gap between the balls. Here, then, was a complete wireless sending and receiving apparatus, but it would work only a short distance, probably not over 100 feet. But Hertz was not trying to invent a wireless telegraph; all he wanted to and did do was to prove that there were long electric waves and there his work ended. [Illustration: Coherer]