“Well, suppose we wanted to locate the point of origin of some strange message heard at the radio station out at Golden Gate Park. First, we would use a sound detector there, and find out along what line the strange sound came to the station. It might be up the coast or down, or east, southeast or
northeast. Suppose it came from down the coast, or south. Then, at a point southeast of this city, we would again apply the sound detector and again at a third point south of the second. When at all three stations, the strange sound was loudest, we would have three bearings upon the point of its origin. Where they intersected, the——”
“The smuggler’s cove would be located,” said Frank quick-tongued.
The next moment he was covered with confusion as Mr. Bender regarded him blankly. So intent had the inventor been upon the description of his device and the method of its operation that he was aware only of an interruption but did not realize the nature of it.
Jack and Bob glared at Frank.
“Eh?” said Mr. Bender. “What say?”
“I just said something about the point of origin being where the lines intersected,” declared Frank, considering it wise to withhold the whole truth, inasmuch as the matter of the smugglers was not his to divulge.
“Yes, certainly,” said Mr. Bender, abstractedly. “Yes, project imaginary lines from each station and where they intersect will be the station you are hunting.”
Abruptly he put aside the sound detector as if, now
that he had explained its operation, it were of no more value.