A hasty search of Shop 13 did not reveal anything missing, and it was surmised (for Schwen would not talk) that he had not found time to go about and get all that he was after. Soon after Schwen's arrest the "Spy Tree," as Tom called it, was cut down. "Eradicate certainly did better than I ever expected he would," declared Tom. "Well, if all goes well, there won't be so much need for secrecy after a day or so. We're going to give her a test, and then--" "Give who a test?" asked Ned, with a smile. "You'll soon see," answered Tom, with an answering grin. "I hereby invite you and Mr. Damon to come over to Shop Thirteen day after to-morrow night and then--Well, you'll see what you'll see." With this Ned had to be content, and he waited anxiously for the appointed time to come. "I surely will be glad when Tom is more like himself," he mused, as he left his chum. "And I guess Mary will be, too. I wonder if he's going to ask her to the exhibition?" It developed that Tom had done so, a fact which Ned learned on the morning of the day set for the test. "Come over about nine o'clock," Tom said to his chum. "I guess it will be dark enough then." Meanwhile Schwen and Otto Kuhn, the other man involved, had been locked up, and all their papers given into the charge of the United States authorities. A closer guard than ever was kept over No. 13 shop, and some of the workmen, against whom there was a slight suspicion, were transferred. "Well, we'll see what we shall see," mused Ned on the appointed evening, when a telephone message from Mr. Damon informed the young bank clerk that the eccentric man was coming to call for him before going on to the Swift place. Chapter X A Runaway Giant "What do you think it's all about, Mr. Damon?" "I'm sure I don't know, Ned." The two were at the home of the young bank clerk, preparing to start for the Swift place, it being nearly nine o'clock on the evening named by the youthful inventor. "Bless my hat-rack!" went on the eccentric man, "but Tom isn't at all like himself of late. He's working on some invention, I know that, but it's all I do know. He hasn't given me a hint of it." "Nor me, nor any of his friends," added Ned. "And he acts so oddly about enlisting--doesn't want even to speak of it. How he got exempted I don't know, but I do know one thing, and that is Tom Swift is for Uncle Sam first, last and always!" "Oh, of course!" agreed Mr. Damon. "Well, we'll soon know, I guess. We'd better start, Ned." "It's useless to try to guess what it is Tom is up to. He has kept his secret well. The nearest any one has come to it was when Harry figured out that Tom had a band of giant elephants which he was fitting with coats of steel armor to go against the Germans," observed Ned, when he and Mr. Damon were on their way. "Well, that mightn't be so bad," agreed Mr. Damon. "But--um--elephants--and wild giant ones, too! Bless my circus ticket, Ned! do you think we'd better go in that case?"