The instrument necessary for receiving messages from the atmosphere is most simple in construction, especially in those commercial machines designed for use by the general public. That required for ordinary usage is a simple aerial, a tuner, a detector, an amplifier, and a reproducer. The purpose of the first is to draw from the ether the electrical impulse, and consists of a single wire under 50 yards in length or a pair of wires about half as long. The tuner is for the purpose of adjusting the instrument to the desired wave length, as all messages, depending on their nature, the station sending and the distance sent, have their own distinct length, ranging from several hundred metres to nearly two miles. Most sets are constructed for a certain range, outside which it is impossible to receive, the cheaper and simpler registering from 200 to 900 metres. The detector satisfies or changes the energy from the sender to such a nature that it can be reproduced and heard, for in transmission of a message the spoken word is transformed into electric impulses, then on reception is converted into its original state. An amplifier must be used when the message is sent a distance, for the greater the distance the weaker the impulse. As its name signifies, it amplifies or enlarges by the aid of batteries that faint "word." The most modern form of amplifier is merely a vacuum tube of special make. Finally, for use in the home, in order to translate the electrical energy into sound waves, the reproducer is used. The head telephone as seen in the wireless cabins on steamships or in the moving pictures of a wireless operator, completes the equipment necessary to. utilize the benefits of a broadcasting station.
Large audiences seated under a single roof or widely scattered on the seashore or along the banks of a river may easily be reached by a device which increases the volume of the sound to any scote desired. 3x-President Wilson addressed the sailors on their ships while at anchor in the harbour. Public announcements are daily made to crowds in the streets, while traffic may be cleared for the speeding fire engines by the use of an amplifier. Stepping the voltage system to the ordinary circuit in the city with proper amperage might easily break and shatter any windows receiving the full force of the vibrations at close range.
Text read from the printed page and cleaned; old type leaves the occasional error.