messages intended for another, but this is being overcome by the
adoption of a special system of wave lengths for the different wireless
stations and by the use of improved apparatus.

In the early days it was quite a common occurrence for the receivers
of one system to reply to the transmitters of a rival system. There
was an all-round mix-up and consequently the efficiency of wireless
for practical purposes was for a good while looked upon with more or
less suspicion. But as knowledge of wave motions developed and the
laws of governing them were better understood, the receiver was "tuned"
to respond to the transmitter, that is, the transmitter was made to
set up a definite rate of vibrations in the ether and the receiver
made to respond to this rate, just like two tuning forks sounding the
same note.

In order to set up as energetic electric waves as possible many methods
have been devised at the transmitting stations. In some methods a wire
is attached to one of the two metal spheres between which the electric
charge takes place and is carried up into the air for a great height,
while to the second sphere another wire is connected and which leads
into the earth. Another method is to support a regular network of wires
from strong steel towers built to a height of two hundred feet or more.

Long distance transmission by wireless was only made possible by
grounding one of the conductors in the transmitter. The Hertzian waves
were provided without any earth connection and radiated into space in
all directions, rapidly losing force like the disappearing ripples on
a pond, whereas those set up by a grounded transmitter with the
receiving instrument similarly connected to earth, keep within the
immediate neighborhood of the earth.