Chapter I - A Suspicious Jeweler

"Well, Tom Swift, I don't believe you will make any mistake if you buy that diamond," said the jeweler to a young man who was inspecting a tray of pins, set with the sparkling stones. "It is of the first water, and without a flaw."

"It certainly seems so, Mr. Track. I don't know much about diamonds, and I'm depending on you. But this one looks to be all right."

"Is it for yourself, Tom?"

"Er--no--that is, not exactly," and Tom Swift, the young inventor of airships and submarines, blushed slightly.

"Ah, I see. It's for your housekeeper, Mrs. Baggert. Well, I think she would like a pin of this sort. True, it's rather expensive, but--"

"No, it isn't for Mrs. Baggert, Mr. Track," and Tom seemed a bit embarrassed.

"No? Well, then, Tom--of course it's none of my affair, except to sell you a good stone, But if this brooch is for a young lady, I can't recommend anything nicer. Do you think you will take this; or do you prefer to look at some others?"

"Oh, I think this will do, Mr. Track. I guess I'll take--"

Tom's Words were interrupted by a sudden action on the part of the jeweler. Mr. Track ran from behind the showcase and hastened toward the front door.

"Did you see him, Tom?" he cried. "I wonder which way he went?"

"Who?" asked the lad, following the shopkeeper.

"That man. He's been walking up and down in front of my place for the last ten minutes--ever since you've been in here, in fact, and I don't like his looks."

"What did he do?"

"Nothing much, except to stare in here as if he was sizing my place up."

"Sizing it up?"

"Yes. Getting the lay of the land, so he or some confederate could commit a robbery, maybe."

"A robbery? Do you think that man was a thief?"

"I don't know that he was, Tom, and yet a jeweler has to be always on the watch, and that isn't a joke, either, Tom Swift. Swindlers and thieves are always on the alert for a chance to rob a jewelry store, and they work many games."

"I didn't notice any particular man looking in here," said Tom, who still held the diamond brooch in his hand.

"Well I did," went on the jeweler. "I happened to glance out of the window when you were looking at the pins, and I saw his eyes staring in here in a suspicious manner. He may have a confederate with him, and, when you're gone, one may come in, and pretend to want to look at some diamonds. Then, when I'm showing him some, the other man will enter, engage my attention, and the first man will slip out with a diamond ring or pin. It's often done."

"You seem to have it all worked out, Mr. Track," observed the lad, with