it oscillates uniformly, it will create, or generate, a definite number of waves per minute, all being of uniform length and size.
If now we substitute a similar spring and weight for the chip as a receiving device (shown at the right in Fig. 2), and place this within the radius of the transmitted waves, these waves in passing will set it in motion, as it oscillates at exactly the same frequency as the transmitting weight. If the receiving device did not oscillate at the same rate as the transmitter, and, therefore, was not in harmony with the transmitted waves, these would tend to counteract any motion imparted to the receiving spring-suspended weight, as the following example should make clear. Assume the receiving weight to be of such dimensions that it will oscillate once per second. Now if the sending weight be generating waves at the rate of two per second, the first wave will give the receiving weight an upward motion at its own frequency; but just as it starts on its downward stroke, the second wave will strike it, thus preventing any further motion of the weight.
It is, therefore, evident that the oscillations of the receiving device would be destroyed if the frequency did not harmonize with that of the sending device. Tuning is absolutely necessary for the successful operation of wireless telegraphy, and it should be thoroughly understood before continuing.
