"Not more rules but different ones," Bob said. "You see their nearness to other ships makes this imperative. Each ship has to take care not to knock out the apparatus of its neighbor by inconsiderate use of a high-power current; also it must not cause undue interference. In other words, a bevy of ships, like a group of persons, must be courteous to one another. If a ship within a ten-mile radius of another is receiving signals that are so faint that they are difficult to distinguish, a neighboring vessel should not complicate matters by trying to transmit a message until the other ship has received what was coming in. This rule makes for ordinary politeness, that is all."
"Couldn't the ship waiting to talk send a message in a different wave length?" inquired Dick.
"Oh, yes; that would be quite possible, if the tune varied enough to make it perfectly distinct."
"But what about high-power stations?" demanded Walter. "They handle important stuff and of course cannot keep stopping for other people to talk. Don't their powerful currents damage the receiving sets in stations near them? I should think they might even injure their own."
"High-power, or long-distance stations have still another problem to meet and they meet it in a different 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 antennæ. 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.