"tom how soon can we go?" asked professor bumper, as he began arranging his papers, maps and documents ready to place them back in the valise.

"within a week, if you want to start that soon."

"the sooner the better. a week will suit me. i don't know just what beecher's plans are, but, he may try to get on the ground first. though, without boasting, i may say that he has not had as much experience as i have had, thanks to you, tom, when you helped me find the lost city of pelone."

"well, i hope we'll be as successful this time," murmured tom. "i don't want to see beecher beat you."

"i didn't know you knew him, tom," said the professor.

"oh, yes, i have met him, once," and there was something in tom's manner, though he tried to speak indifferently, that made ned believe there was more behind his chum's sudden change of determination than had yet appeared.

"he never mentioned you," went on professor bumper; "yet the last time i saw him i said i was coming to see you, though i did not tell him why."

"no, he wouldn't be likely to speak of me," said tom significantly.

"well, if that's all settled, i guess i'll go back home and pack up," said mr. damon, making a move to depart.

"there's no special rush," tom said. "we won't leave for a week. i can't get ready in much less time than that."

"bless my socks! i know that," ejaculated mr. damon. "but if i get my things packed i can go to a hotel to stay while my wife is away. she might take a notion to come home unexpectedly, and, though she is a dear, good soul, she doesn't altogether approve of my going off on these wild trips with you, tom swift. but if i get all packed, and clear out, she can't find me and she can't hold me back. she is visiting her mother now. i can send her a wire from kurzon after i get there."

"i don't believe the telegraph there is working," laughed professor bumper. "but suit yourself. i must go back to new york to arrange for the goods we'll have to take with us. in a week, tom, we'll start."

"you must stay to dinner," tom said. "you can't get a train now anyhow, and father wants to meet you again. he's pretty well, considering his age. and he's much better i verily believe since i said i'd turn over to him the task of finishing the stabilizer. he likes to work."

"we'll stay and take the night train back," agreed mr. damon. "it will be like old times, tom," he went on, "traveling off together into the wilds. central america is pretty wild, isn't it?" he asked, as if in fear of being disappointed on that score.

"oh, it's wild enough to suit any one," answered professor bumper.

"well, now to settle a few details," observed tom. "ned, what is the situation as regards the financial affairs of my father and myself? nothing will come to grief if we go away, will there?"

"i guess not, tom. but are you going to take your father with you?"

"no, of course not."

"but you spoke of 'we.'"

"i meant you and i are going."

"me, tom?"

"sure, you! i wouldn't think of leaving you behind. you want ned along, don't you, professor?"

"of course. it will be an ideal party—we four. we'll have to take natives when we get to honduras, and make up a mule pack-train for the interior. i had some thoughts of asking you to take an airship along, but it might frighten the indians, and i shall have to depend on them for guides, as well as for porters. so it will be an old-fashioned expedition, in a way."

mr. swift came in at this point to meet his old friends.

"the boy needs a little excitement," he said. "he's been puttering over that stabilizer invention too long. i can finish the model for him in a very short time."

professor bumper told mr. swift something about the proposed trip, while mr. damon went out with tom and ned to one of the shops to look at a new model aeroplane the young inventor had designed.

there was a merry party around the table at dinner, though now and then ned noticed that tom had an abstracted and preoccupied air.

"thinking about the idol of gold?" asked ned in a whisper to his chum, when they were about to leave the table.

"the idol of gold? oh, yes! of course! it will be great if we can bring that back with us." but the manner in which he said this made ned feel sure that tom had had other thoughts, and that he had used a little subterfuge in his answer.

ned was right, as he proved for himself a little later, when, mr. damon and the professor having gone home, the young financial secretary took his friend to a quiet corner and asked:

"what's the matter, tom?"

"matter? what do you mean?"

"i mean what made you make up your mind so quickly to go on this expedition when you heard beecher was going?"

"oh—er—well, you wouldn't want to see our old friend professor bumper left, would you, after he had worked out the secret of the idol of gold? you wouldn't want some young whipper-snapper to beat him in the race, would you, ned?"

"no, of course not."

"neither would i. that's why i changed my mind. this beecher isn't going to get that idol if i can stop him!"

"you seem rather bitter against him."

"bitter? oh, not at all. i simply don't want to see my friends disappointed."

"then beecher isn't a friend of yours?"

"oh, i've met him, that is all," and tom tried to speak indifferently.

"humph!" mused ned, "there's more here than i dreamed of. i'm going to get at the bottom of it."

but though ned tried to pump tom, he was not successful. the young inventor admitted knowing the youthful scientist, but that was all, tom reiterating his determination not to let professor bumper be beaten in the race for the idol of gold.

"let me see," mused ned, as he went home that evening. "tom did not change his mind until he heard beecher's name mentioned. now this shows that beecher had something to do with it. the only reason tom doesn't want beecher to get this idol or find the buried city is because professor bumper is after it. and yet the professor is not an old or close friend of tom's. they met only when tom went to dig his big tunnel. there must be some other reason."

ned did some more thinking. then he clapped his hands together, and a smile spread over his face.

"i believe i have it!" he cried. "the little green god as compared to the idol of gold! that's it. i'm going to make a call on my way home."

this he did, stopping at the home of mary nestor, a pretty girl, who, rumor had it, was tacitly engaged to tom. mary was not at home, but mr. nestor was, and for ned's purpose this answered.

"well, well, glad to see you!" exclaimed mary's father. "isn't tom with you?" he asked a moment later, seeing that ned was alone.

"no, tom isn't with me this evening," ned answered. "the fact is, he's getting ready to go off on another expedition, and i'm going with him."

"you young men are always going somewhere," remarked mrs. nestor. "where is it to this time?"

"some place in central america," ned answered, not wishing to be too particular. he was wondering how he could find out what he wanted to know, when mary's mother unexpectedly gave him just the information he was after.

"central america!" she exclaimed. "why, father," and she looked at her husband, "that's where professor beecher is going, isn't it?"

"yes, i believe he did mention something about that."

"professor beecher, the man who is an authority on aztec ruins?" asked ned, taking a shot in the dark.

"yes," said mr. nestor. "and a mighty fine young man he is, too. i knew his father well. he was here on a visit not long ago, young beecher was, and he talked most entertainingly about his discoveries. you remember how interested mary was, mother?"

"yes, she seemed to be," said mrs. nestor. "tom swift dropped in during the course of the evening," she added to ned, "and mary introduced him to professor beecher. but i can't say that tom was much interested in the professor's talk."

"no?" questioned ned.

"no, not at all. but tom did not stay long. he left just as mary and the professor were drawing a map so the professor could indicate where he had once made a big discovery."

"i see," murmured ned. "well, i suppose tom must have been thinking of something else at the time."

"very likely," agreed mr. nestor. "but tom missed a very profitable talk. i was very much interested myself in what the professor told us, and so was mary. she invited mr. beecher to come again. he takes after his father in being very thorough in what he does.

"sometimes i think," went on mr. nestor, "that tom isn't quite steady enough. he's thinking of so many things, perhaps, that he can't get his mind down to the commonplace. i remember he once sent something here in a box labeled 'dynamite.' though there was no explosive in it, it gave us a great fright. but tom is a boy, in spite of his years. professor beecher seems much older. we all like him very much."

"that's nice," said ned, as he took his departure. he had found out what he had come to learn.

"i knew it!" ned exclaimed as he walked home. "i knew something was in the wind. the little green god of jealousy has tom in his clutches. that's why my inventive friend was so anxious to go on this expedition when he learned beecher was to go. he wants to beat him. i guess the professor has plainly shown that he wouldn't like anything better than to cut tom out with mary. whew! that's something to think about!"