WIRELESS TELEGRAPHY

Primitive Signalling--Principles of Wireless Telegraphy--Ether
Vibrations--Wireless Apparatus--The Marconi System.


At a very early stage in the world's history, man found it necessary
to be able to communicate with places at a distance by means of signals.
Fire was the first agent employed for the purpose. On hill-tops or
other eminences, what were known as beacon fires were kindled and owing
to their elevation these could be seen for a considerable distance
throughout the surrounding country. These primitive signals could be
passed on from one point to another, until a large region could be
covered and many people brought into communication with one another.
These fires expressed a language of their own, which the observers
could readily interpret. For a long time they were the only method
used for signalling. Indeed in many backward localities and in some
of the outlying islands and among savage tribes the custom still
prevails. The bushmen of Australia at night time build fires outside
their huts or kraals to attract the attention of their followers.

Even in enlightened Ireland the kindling of beacon fires is still
observed among the people of backward districts especially on May Eve
and the festival of mid-summer. On these occasions bonfires are lit
on almost every hillside throughout that country. This custom has been
handed down from the days of the Druids.

For a long time fires continued to be the mode of signalling, but as
this way could only be used in the night, it was found necessary to
adopt some method that would answer the purpose in daytime; hence