Not long afterward the arrested men were convicted and sentenced to long prison terms. It developed that they were old offenders who made a specialty of robbery at summer resorts.
Larry grew steadily better and there was every prospect that his lameness would in time wholly disappear. But he was doing so well at the broadcasting station that he determined to give up any further idea of vaudeville and devote himself to radio, going to a technical school in the meantime to perfect his education. Tim steadily advanced in his chosen vocation, and the boys heard from him frequently. No one rejoiced more than they when they learned that he was at last in the big-time circuit.
During all these events the boys had been busy at developing the receiving set, and at last it was finished to their satisfaction. In the course of their work they gathered a large amount of familiarity with radio which proved of immense value later on, as will be seen in the next volume of this series, ent.i.tled: "The Radio Boys at Mountain Pa.s.s; Or, The Midnight Call For a.s.sistance."
The special set that represented the advance they had made in radio reception included the regenerative principle. This feature added immensely to the sensitiveness of the set. It consisted of a coil, variously known as the tickler, the intensity coil, and the regeneration coil. It involved three controls, the wave-length tuning, the regenerative coil, and the filament rheostat. The result of the combination was not only that the radio frequency waves could be carried over into the plate circuit, but that they could be amplified there by the energy derived from the local battery in the plate circuit without change of frequency or wave form, and that they could be fed into the grid circuit, where they increased the potential variations on the grid so that the operation constantly repeated itself.
This "feed-back" regeneration enormously increased the loudness of the receiving signals, and its value to the boys was demonstrated one night when the air was unusually free of static and they clearly heard the signals from Nauen, Germany, and the Eiffel Tower, Paris. They looked at each other incredulously at first, and then as they heard the signals again too certainly to admit of doubt, they jumped to their feet, clapped each other on the shoulder, and fairly went wild with delight.
"The first boys in this old town to pick up a message from Europe!" cried Joe. "What next?"
"Asia perhaps," suggested Jimmy.
"Then Australia," ventured Herb.
"Or Mars," predicted Bob. "Who knows?" he added, as he saw the smile of doubt on his comrades" faces. "Marconi thought he might, and he"s no dreamer. What is impossible to radio?"
THE END