"What's the matter, Tom? What is it?" asked Ned Newton, attracted by the strange manner of his chum at the telephone. "Has anything happened?"

But the young inventor was too busy listening to the unseen speaker to answer his chum, even if he heard what Ned remarked, which is doubtful.

"Well, I might as well wait until he is through," mused Ned, as he started to leave the room. Then as Tom motioned to him to remain, he murmured: "He may have something to say to me later. But I wonder who is talking to him."

There was no way of finding out, however, until Tom had a chance to talk to Ned, and at present the young scientist was eagerly listening to what came over the wire. Occasionally Ned could hear him say:

"You don't tell me! That is surprising! Yes --yes! Of course if it's true it means a big thing, I can understand that. What's that? No, I couldn't make a promise like that. I'm sorry, but----"

Then the person at the other end of the wire must have plunged into something very interesting and absorbing, for Tom did not again interrupt by interjected remarks.

Tom. Swift, as has been said, was an inventor, as was his father. Mr. Swift was now rather old and feeble, taking only a nominal part in the activities of the firm made up of himself and his son. But his inventions were still used, many of them being vital to the business and trade of this country.

Tom and his father lived in the village of Shopton, New York, and their factories covered many acres of ground. Those who wish to read of the earliest activities of Tom in the inventive line are referred to the initial volume, "Tom Swift and His Motor Cycle." From then on he and his father had many and exciting adventures. In a motor boat, an airship, and a submarine respectively the young inventor had gone through many perils. On some of the trips his chum, Ned Newton, accompanied him, and very often in the party was a Mr. Wakefield Damon, who had a curious habit of "blessing" everything that happened to strike his fancy.

Besides Tom and his father, the Swift household was made up of Eradicate Sampson, a colored man-of-all-work, who, with his mule Boomerang, did what he could to keep the grounds around the house in order. There was also Mrs. Baggert, the housekeeper, Tom's mother being dead. Mr. Damon, living in a neighboring town, was a frequent visitor in the Swift home.

Mary Nestor, a girl of Shopton, might also be mentioned. She and Tom were more than just good friends. Tom had an idea that some day----. But there, I promised not to tell that part, at least until the young people themselves were ready to have a certain fact announced.

From one activity to another had Tom Swift gone, now constructing some important invention for himself, as among others, when he made the photo-telephone, or developed a great searchlight which he presented to the Government for use in detecting smugglers on the border.

The book immediately preceding this is called "Tom Swift and His Bit, Tunnel," and deals with the efforts of the young inventor to help a firm of contractors penetrate a mountain in Peru. How this was done and how, incidental- ly, the lost city of Pelone was discovered, bringing joy to the heart of Professor Swyington Bumper, will be found fully set forth in the book.

Tom had been back from the Peru trip for some months, when we again find him interested in some of the work of Professor Bumper, as set forth in the magazine mentioned.

"Well, he certainly is having some conversation," reflected Ned, as, after more than five minutes, Tom's ear was still at the receiver of the instrument, into the transmitter of which he had said only a few words.

"All right," Tom finally answered, as he hung the receiver up, "I'll be here," and then he turned to Ned, whose curiosity had been growing with the telephone talk, and remarked:

"That certainly was wonderful!"

"What was?" asked Ned. "Do you think I'm a mind reader to be able to guess?"

"No, indeed! I beg your pardon. I'll tell you at once. But I couldn't break away. It was too important. To whom do you think I was talking just then?"

"I can imagine almost any one, seeing I know something of what you have done. It might be almost anybody from some person you met up in the caves of ice to a red pygmy from the wilds of Africa."

"I'm afraid neither of them would be quite up to telephone talk yet," laughed Tom. "No, this was the gentleman who wrote that interesting article about the idol of gold," and he motioned to the magazine Ned held in his hand.

"You don't mean Professor Bumper!"

"That's just whom I do mean."

"What did he want? Where did he call from?"

"He wants me to help organize an expedition to go to Central America--to the Copan valley, to be exact--to look for this somewhat mythical idol of gold. Incidentally the professor will gather in any other antiques of more or less value, if he can find any, and he hopes, even if he doesn't find the idol, to get enough historical material for half a dozen books, to say nothing of magazine articles."

"Where did he call from; did you say?"

"I didn't say. But it was a long-distance call from New York. The Professor stopped off there on his way from Boston, where he has been lecturing before some society. And now he's coming here to see me," finished Tom.

"What! Is he going to lecture here?" cried Ned. "If he is, and spouts a whole lot of that bone-dry stuff about the ancient Mayan civilization and their antiquities, with side lights on how the old-time Indians used to scalp their enemies, I'm going to the moving pictures! I'm willing to be your financial manager, Tom Swift, but please don't ask me to be a high-brow. I wasn't built for that."

"Nor I, Ned. The professor isn't going to lecture. He's only going to talk, he says."

"What about?"

"He's going to try to induce me to join his expedition to the Copan valley."

"Do you feel inclined to go?"

"No, Ned, I do not. I've got too many other irons in the fire. I shall have to give the professor a polite but firm refusal."

"Well, maybe you're right, Tom; and yet that idol of gold--gold--weighing how many pounds did you say?"

"Oh, you're thinking of its money value, Ned, old man!"

"Yes, I'd like to see what a big chunk of gold like that would bring. It must be quite a nugget. But I'm not likely to get a glimpse of it if you don't go with the professor."

"I don't see how I can go, Ned. But come over and meet the delightful gentleman when he arrives. I expect him day after to-morrow."

"I'll be here," promised Ned; and then he went downtown to attend to some matters con- nected with his new duties, which were much less irksome than those he had had when he had been in the bank.

"Well, Tom, have you heard any more about your friend?" asked Ned, two days later, as he came to the Swift home with some papers needing the signature of the young inventor and his father.

"You mean----?"

"Professor Bumper."

"No, I haven't heard from him since he telephoned. But I guess he'll be here all right. He's very punctual. Did you see anything of my giant Koku as you came in?"

"Yes, he and Eradicate were having an argument about who should move a heavy casting from one of the shops. Rad wanted to do it all alone, but Koku said he was like a baby now."

"Poor Rad is getting old," said Tom with a sigh. "But he has been very faithful. He and Koku never seem to get along well together."

Koku was an immense man, a veritable giant, one of two whom Tom had brought back with him after an exciting trip to a strange land. The giant's strength was very useful to the young inventor.

"Now Tom, about this business of leasing to the English Government the right to manufac- ture that new explosive of yours," began Ned, plunging into the business at hand. "I think if you stick out a little you can get a better royalty price."

"But I don't want to gouge 'em, Ned. I'm satisfied with a fair profit. The trouble with you is you think too much of money. Now----"

At that moment a voice was heard in the hall of the house saying:

"Now, my dear lady, don't trouble yourself. I can find my way in to Tom Swift perfectly well by myself, and while I appreciate your courtesy I do not want to trouble you."

"No, don't come, Mrs. Baggert," added another voice. "Bless my hat band, I think I know my way about the house by this time!"

"Mr. Damon!" ejaculated Ned.

"And Professor Bumper is with him," added Tom. "Come in!" he cried, opening the hall door, to confront a bald-headed man who stood peering at our hero with bright snapping eyes, like those of some big bird spying out the land from afar. "Come in, Professor Bumper; and you too, Mr. Damon!"