rent way," responded Bob. "In order
that the currents they are obliged to use shall not destroy detectors
and other delicate receiving apparatus they carry on what are known as
duplex operations. That is, the receiving station is constructed at
some distance from the sending station--often several miles away--and
the two parts of the service are performed independently by different
antennae. In this way sending and receiving can be carried on at the
same time in slightly varying wave lengths."

"But how can they talk and act as one station if they are so far
apart?" questioned His Highness much puzzled.

"It is not as impossible as it seems. The operator at the sending
station has a small sending key connected by electricity with a relay
at the receiving station. By means of a lever and certain complex
paraphernalia this key can be used as the sending key for the main
apparatus. Thus the station operated by distant control carries on a
duplex system of transmission so that both sending and receiving
stations are kept in touch with one another."

"That is clever!" interrupted Mr. Crowninshield.

"A high-power station has to be ingeniously equipped," responded Bob,
"for it does a great deal of business, rapid business and business
that is important. In some stations so fast do the messages come in
and so long are they that an automatic tape not unlike that seen at
the stock exchange is used to make perforated records of the dots and
dashes. Later this punctured slip can be run through a Morse writer
and the message taken down at leisure by the operator. Or sometimes
photographic or phonographic records are resorted to and these like
the others can be reproduced at a slower rate of speed and interpreted
by the operator."

"I should like that and then I wouldn't have to hurry," murmured
Nancy.

"It must be jolly to be an operator in a long-distance station," mused
Dick, "where real things are going on."

"Perhaps it is," was Bob's nonchalant answer. "I fancy, though, that
very vital government messages go in cipher. Uncle Sam isn't risking
having his secrets published far and wide over the face of the whole
earth. Although for that matter all radio messages are secret."

"But how can they be if any and everybody can listen in?"

"Well, on a high-power wave length probably ordinary persons would not
be able to listen in. Their apparatus would not be equipped for it.
Should a station be able to, however, during cri