If we drop a stone into water, it sends out circular waves which become gradually feebler and feebler as the distance increases. At a distance of twenty feet they are twice as feeble as they are at a distance of ten feet. Their crests only reach half the height. Bad as this is, it is much worse in the case of light, and very much worse in the case of magnetism. In the case of light only a quarter of the strength remains when we double the distance, and in the case of magnetism only one-eighth remains. If, however, we could have some system of telegraphy resembling water waves it would be a great deal better than any other kind. And this is precisely the way in which the inventors of wireless telegraphy attained their triumph. The first man to produce waves of electricity, and to prove that they were waves of electricity, was a German professor of the name of Hertz. He lived at Bonn on the Rhine, and spent a great deal of time trying to prove that electric force does not spread out into space instantly, but takes time to reach a distant point. He found that this time was very short indeed. He found, in fact, that the speed of electricity is the same as the speed of light. He proved that if electricity is made to surge up and down an electric wire, a wave of electric force travels out in all directions. If such a wave falls upon a sheet of metal, it is reflected just as light is reflected from a mirror. A similarity to light also appeared in many other properties of the electric waves or radiations. These could be concentrated by a curved mirror, and refracted by a large prism of pitch. These waves of electric force are indeed a kind of light waves. But whereas light waves are so short that some fifty thousand of them go to the inch, the waves which Hertz discovered were each several yards long.