Doctor Marley venturing a timid question as to how he was to return to San Francisco, Mr. Temple entered into conversation with him. Ensign Warwick went to attend to his duties. The boys drew aside, and, leaning on the rail, stared into the thinning fog ahead and discussed their chances of seeing further action.
All were agreed that the veiled hint dropped by Inspector Burton indicated he had obtained a clue that the smugglers were somewhere along the adjacent coast. They speculated upon whether Inventor Bender’s sound detector had provided the clue, or whether there had been sufficient time for the detector to be brought into play.
“You see,” Jack pointed out, “the inventor planned to use sound detectors at several places pretty widely scattered, and it would take him some time to set them up.”
“That’s true,” said Frank, “but the device required no time at all to hook up. The time needed would be for making the trip from San Francisco to the other stations. Say——”
His face lighted up.
“What?” asked Bob.
“Why, didn’t Inspector Burton, when we saw him last in San Francisco, say one of the government radio stations which he planned to utilize in employing the sound detector was in the mountains behind Santa Barbara?”
“I don’t remember that,” said Bob, and Jack also shook his head.
“Well, that’s what he said,” declared Frank. “I’m certain of it.”
“In that case,” said Jack, “perhaps through the use