current itself came from a small, but powerful, storage battery, and
it had been switched on. The current also set in motion a toothed
wheel of brass. This wheel revolved on its axis with the points,
or teeth, passing rapidly in front of a platinum contact point.

As each tooth thus came in opposition to the point, a blue spark of
electricity would shoot out with a vicious snap; that is if the
connection key were pressed down. If the key were not depressed no
current flowed.

I presume most of you understand how the wireless works, so I will
not give you a complete description save to say that it is just like
a telegraph system, in fundamentals. The only difference is that
no connecting metallic wires are needed between stations.

A group of wires in parallels, called "aerials," are hung in the
air at one point, or station, and a similar set is suspended at the
other station. The electrical current jumps through the air from
one group of wires to the other, without being directly connected,
hence the name "wireless," though really some wires are used.

The electrical impulse can be sent for thousands of miles through
the air, without any directly connecting wires. And the method of
communication is by means of dots, dashes and spaces.

You have doubtless heard the railroad or other telegraph instruments
clicking. You can hold your table knife blade between two tines of
your fork, and imitate the sound of the telegraph very easily.

If you move your knife blade up and down once, quickly, that will