represent a dot. If you move it more slowly, holding it down for
a moment, that would be a dash. A space would be the interval
between a dot and a dash, or between two dots or two dashes.

Thus, by combinations of dots, dashes and spaces, the letters of
the alphabet may be made and words spelled out. For instance a dot
and a dash is "A."

In telegraphing, of course, the operator listens to the clicking of
the brass sounder in front of him on the desk. But in wireless the
electrical waves, or current received, is so weak that it would not
operate the sounder. So a delicate telephone receiver is used.
This is connected to the receiving wires, and as the sender at his
station, perhaps a thousand miles away, presses down his key, and
allows it to come up, thus making dots, dashes and spaces,
corresponding clicks are made in the telephone receiver, at the ear
of the other operator.

It takes skill to thus listen to the faint clicks that may be
spelled out into words, but the operators are very skillful. In
sending messages a very high tension current is needed, as most of
it is wasted, leaping through the air as it does. So that though
the clicks may sound very loud at the sending apparatus, and the
blue sparks be very bright, still only faint clicks can be heard in
the head-telephone receiver at the other end.

"You may send," directed Captain Grantly to Captain Wakefield, and
the blue sparks shot out in a dazzling succession, as the spiked
wheel spun around. This was kept up for some little time, after the
receiving operator at the army headquarters had signified that he