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.
"Here," he said, taking up a suitcase, and swinging it around, "is a radio receiving device that can be carried easily in this small suitcase. And here"-putting down the suitcase before the boys could examine it and taking up a finger ring from a workbench-"is the smallest receiving set I have yet devised. It is, as you see, in the shape of a ring and can be worn without the presence of the device being suspected."
"Mr. Bender," said Frank, "will you excuse my friends and me for a few moments while we step aside and have a little confab. I believe we will have a proposal to make that will interest you."
"I know what you mean," said Frank, as Mr. Bender withdrew, leaving them alone. "That sound detector, hey? If the Secret Service man had that he would be able to locate the smuggler's cove."
"That's it, exactly," said Jack. "Inspector Burton said he would not be leaving for Los Angeles until tonight. I believe we ought to get hold of him at once and tell him about this possibility."
"I'm with you," said Bob. "But we don't know how to reach him. Suppose I call Father at the office of his business representative, and ask him to get Inspector Burton."
"Good idea," said Jack. "I didn't know just how to work it. But if your father gets Inspector Burton to come up here, we will not be revealing anything to Mr. Bender, and the inspector can tell as much or little as he wants."
"Then I'll telephone father," said Bob. "I saw a telephone in the store when we came in. I suppose Mr. Bender will let me use it."
"And I'll explain as much as necessary to Mr. Bender," said Jack.
Accordingly, he called the inventor back to the workroom while Bob telephoned Mr. Temple, and explained they were inviting a man to come up and talk to him about the sound detector.
"I can't tell you any more than that now, Mr. Bender," said Jack. "But I promise you, of course, that your invention is not in any danger of being stolen. On the contrary, the man we have asked to come here may put you in the way of making your fortune."
CHAPTER VI
IN THE ENEMY'S TOILS
"Look here," said Mr. Temple, "you boys have done a fine stroke of business for the government today. Suppose you play a little tonight?"
They were finishing dinner at a famous restaurant. All about them were tables with gay little parties. The concealed orchestra was playing a popular air. Mr. Temple leaned back, sighed comfortably and lighted a cigar. The boys went on with their dessert.
"It was a good stroke of business, Dad, wasn't it?" said Bob. "Getting that old inventor with his sound detector at just the right moment, and catching Inspector Burton before he left for the south. With that invention, he ought to be able to locate the smugglers' radio station."
"Sh, Bob, not so loud," warned Frank. "Somebody might hear us."
All looked around furtively. They occupied a separate table, however, and there was none other near enough for its occupants to overhear their conversation.
"For my part," said Jack, "I'm sorry we aren't going to be in on the outcome of this business."
"Same here," said Frank. "Here we go and start the ball to rolling, and then have to drop out, without a chance to see where it rolls to."
"Hard luck," agreed Bob. "That's what it is."
Mr. Temple shook his head.
"I should think you would have had enough adventures on the Mexican border," he said, "to last you the rest of your lives. Yet here you are lamenting because you can't have more. Besides, this matter can be of no particular concern to you."
"Just the same," said Frank, "it is. We have a personal interest in the matter. We started it by overhearing the plotters. Then we found this inventor with his sound detector that probably will enable the Secret Service to locate the smugglers' radio plant and secret cove. Now we are calmly shouldered out of the way. It's hard luck, as Bob says."
Mr. Temple smiled tolerantly.
"You can't expect me to sympathize with you very much," he said. "Well, now, which shall it be? The theatre or a prowl around Chinatown?"
Chinatown? In a moment the pessimism of the boys vanished. They were all smiles.
"Chinatown by all means," said Jack, emphatically.
"Righto," agreed Bob.
"With its opium dens and hatchet men and gambling clubs and all,"
declared Frank.
"Oh, it isn't what it used to be," deprecated Mr. Temple. "I understand Chinatown is quite civilized now. Nevertheless, I expect we shall find much to interest us. I'll speak to the head waiter. Probably he can direct us to a guide."
On being consulted, the head waiter agreed to obtain them a guide.
Presently, the boys and Mr. Temple were on their way by auto to the unique city within a city which constitutes San Francisco's Chinatown, a quarter housing more than 30,000 Chinese. Oriental in every characteristic, with narrow alleys and courts, cellars, sub-cellars and sub-sub-cellars, the dragon roofs of Chinatown lie just below Nob Hill, the old aristocratic quarter of San Francisco with its veritable palaces of stone. From the terraces of the latter, one can look down into the alleys of Chinatown. So close neighbors are these two opposite districts of the city by the Golden Gate.
At the corner of Grant (once called Dupont) and California Streets, the guide halted their car and the party alighted. The boys looked around them with delight. In every direction were houses and stores speaking of the Orient. Close at hand on one corner was a Catholic church, one of the landmarks of the district. On another corner was a restaurant from which came strange Chinese music.
Up the California Street hill droned a strange little cable car, its sides open and passengers facing outward. Below, clear in the moonlight, lay the Bay with a lighted ferryboat making the crossing.
While the boys were drinking it all in, and staring owl-eyed at the slippered Chinamen in baggy pants and blouses shuffling past, their guide was in converse with a stranger. Now he approached Mr. Temple and touched his cap.
"Sorry, sir," he said, "but this is where I leave you. I'll turn you over to this man."
Mr. Temple regarded him sharply, then looked at the other.
"Isn't that a bit unusual?" he asked.
"No, sir," said the original guide, "this man has certain territory here which we let him cover by agreement. When he has shown you around, you'll find me here, sir, and I'll continue with you. Shall I dismiss the car, sir? You'll spend some time here, and might as well dismiss it now and get another later, rather than have it eat up fares."
"Very well," said Mr. Temple. "Here." And he handed the man a bill.
Under the conduct of the new guide, the party started down Grant Street.
The original guide watched their disappearing figures several minutes, then walked over to the chauffeur at the wheel of the hired car.
"Gave me a tenner, George," said he. "Here's your split. I wonder what 'Black George' wants with 'em. Look like fruity pickin's all right."