Temple nodded understandingly.

“But this tip about Handby,” said Frank, returning to the first subject, “won’t that help you?”

“It will, indeed,” said Inspector Burton. “Handby is employed in Southern California, operating out of Los Angeles and San Diego. Just to show you how valuable I consider your information, I’ll say that since sitting here I have made up my mind to make a trip immediately to the south myself. Handby shall be put under surveillance at once.”

“Won’t you arrest him and try to make him confess?” queried Jack.

“No. That would scare off the others. I’ll watch Handby in hope that he will lead us to his associates, and thus we will be enabled to scoop in a number of the crooks and break up the smuggling ring.”

“About this radio station in the cove?” said Frank. “You remember? I told you I overheard ‘Black George’ telling his companion the radio at the cove would keep in touch with the coolie boats?”

Inspector Burton nodded.

“That’s important, of course,” he said. “But as

I told you we haven’t sufficient men to make a systematic search of the coast. We’ll have to depend on Handby to betray the station to us.”

“Not necessarily,” interrupted Jack.

Inspector Burton glanced at him inquiringly.

“The government certainly has a powerful radio station or two out here on the Pacific Coast,” said Jack. “Hasn’t it?”

“Why, yes,” answered Inspector Burton. “There’s a big one right here in San Francisco. But, to tell you the truth, I’ve never paid much attention to radio.”

“Well, Jack has,” said Mr. Temple, smiling. “He and his father are radio fans. They have several big stations of their own under special government license, on Long Island and in New Mexico. Jack probably knows more about radio than about anything else.”

“I don’t know whether to take that as a compliment or a slap,” laughed Jack.

“A compliment, my boy, a compliment,” said Mr. Temple, patting him on the shoulder.

“Well,” said Jack, “I’ll confess I was caging a bit when I asked whether the government had stations out here. I know it has. You know, you fellows”—turning to his chums—“how dad and I have studied the history of radio development. I remember that

as far back as 1910 or 1912 the Federal Telegraph Company carried on radio experiments out here between stations at San Francisco, Stockton, Sacramento and Los Angeles.”

“Is that so?” said Inspector Burton, regarding Jack with increased respect. “Well, what did you mean awhile ago when you intimated it wasn’t necessary to trail Handby in order to locate the smuggling ring’s radio plant.”

“Can you obtain the use of the government radio stations?” countered Jack.

“Certainly.”

“Well, then, to begin with, we can obtain the approximate location of the smugglers’ radio. Of course, they will speak in code, and probably they will use a high wave length in order to avoid the confusion of any amateur sending stations cutting in. Let the government stations here and at Los Angeles tune until they pick up code. If it is weak here and strong at Los Angeles, then the station sending code is nearer the latter city.”

“Well, that won’t help us much,” said Inspector Burton, disappointedly. “We know, of course, that it is bound to be in the southern part of the state, probably even below Los Angeles, in order that the coolie boats can make their run from Mexico in one night.”

“I see,” said Jack, composedly. “But that wasn’t the only thing I had in mind.”

“What else?”

“Let an expert at solving codes listen in when once the code conversations are picked up. He can take down what he hears. The probability is he can work out a solution. To a genuine expert, as I understand it, there is no code that cannot be solved.”

“But,” objected Mr. Temple, “the code picked up and deciphered might be from some station like yours, Jack.”

“In which case you mean it would be about legitimate business?” said Jack. “But the government will have licensed stations listed, and their codes on file. No, I believe it would be a good move to put a code expert at work at the Los Angeles station.”

“So do I,” said Inspector Burton, warmly. “I want to thank you. And I want to thank you, too,” he added, turning to Frank. “Your information will undoubtedly prove to be of the very greatest value.”

He rose.

“I shall have to go now,” he said. “I suppose you all will be viewing the city and taking in the sights. I wish I could stay to show it to you. But that cannot be. What you have told me makes

it necessary for me to leave at once for the south. I shall arrange my affairs here and take the night train to Los Angeles. I may not see you again. But I know you will be interested in the outcome and”—turning to Mr. Temple—“if you give me your address I promise to let you know.”

Mr. Temple took out a business card and handed it to the other. Then he accompanied him to the door.

“Good-bye,” called the chums, in chorus. “Good luck.”

“Well,” said Bob, when his father returned, “that’s that. Now, Dad, you will want to attend to your business affairs today. What do you suggest we do?”

“Hire a car,” said his father, promptly, “and drive around the city. Be back here at five. Then we’ll dress and have dinner in one of the city’s famous restaurants. San Francisco is noted for its wonderful dining places. Afterward, we can all go to a theatre or just walk around and view the city at night.”

CHAPTER V—THE SOUND DETECTOR

“Where to, first?” queried Frank. “I vote for the Cliff House and Seal Rocks. Here in the guide book it says ‘the seals play sportively in the restless tide.’ And Sutro Baths are nearby, too, I gather—the largest indoor salt water pool in the world.”

All three chums stood on the Market Street sidewalk before the Palace Hotel. The hour was near eleven. The usual early morning fog which had hung over the city, as it does practically every day of the year, had been dissipated for an hour or more. The sky was cloudless and blue, the sunshine brilliant. A brisk breeze blew along the tremendously wide thoroughfare, which is the widest of all the great city streets of the land, so wide, in fact, that it accommodates four street car lines with the width of an ordinary street left over on each side between the outer tracks and the curbs.

“How delightfully cool and exhilarating!” commented big Bob, drawing in and expelling great

lungfuls of the crisp air. “I haven’t felt so peppy in days.”

“The guide book says that’s the San Francisco climate,” said Frank. “Cool, snappy days all the year round.”

“Your car, sir,” said a uniformed doorman to Jack.

They looked up to find a handsome limousine drawn to the curb. This was the car they had ordered for the day. The boys moved toward it.

“We ought to decide right now where we want to go,” declared Frank.

Jack had an inspiration.

“I’ll tell you what, fellows,” he said. “Father gave me the name and address of a man who invented some new radio equipment, and advised me to look him up. Suppose we do that, first. Then we can go sightseeing. It just occurred to me. Wonder where that address is.”

He began leafing over the pages of a small memorandum book.

“Here it is. Bender, Silas Bender. 1453 Mission Street. Let’s ask the chauffeur how far away that is.”

After a little discussion, it developed the address given—on the first street paralleling Market to