John Stone Stone

Of the various problems which have been presented in the course of the development of the new art of wireless telegraphy, none is of greater interest to the engineer, and none is of more far-reaching importance from the industrial and commercial standpoint than that of rendering the receiving instruments of wireless telegraph stations immune from interference.

There are two principal kinds of interference.

1. Interference which arises from electrical charges which accumulate upon the vertical oscillator under various conditions of weather, provided the vertical oscillator has no adequate electrical connection to the earth.

2. Interference which arises from such stray electromagnetic waves as are produced by lighting, by magnetic storms, by sparks in neighboring circuits, such for instance at occur in trolley circuits, and also from wireless telegraph stations other than that with which communication is desired.