"I wouldn't be surprised, Tom. Well, perhaps we can get up a new style of carburetor that will do the trick. Now look at this needle valve; I've given it a new turn," and father and son went into technical details connected with their latest invention. These were busy days at the Swift plant. Men came and went--men with queerly shaped parcels frequently--and they were admitted to the big new building after first passing Eradicate and then Koku, and it would be hard to say which guard was the more careful. Only, of course, Koku had the final decision, and more than one person was turned back after Eradicate had passed him, much to the disgust of the negro. "Pooh! Dat giant don't know a workman when he sees 'im!" snorted Eradicate. "He so lazy his own se'f dat he don't know a workman! Ef I sees a spy, Massa Tom, or a crook, I's gwine git him, suah pop!" "I hope you do, Rad. We can't afford to let this secret get out," said the young inventor. It was one evening, when taking a short cut to his home, that Mr. Nestor, the father of Mary Nestor, in whom Tom was more than ordinarily interested, passed not far from the big enclosure which was guarded, on the factory side, day and night. Inside, though out of sight and hidden by the high fence, were other guards. As Mr. Nestor passed along the fence, rather vaguely wondering why it was so high, tight and strong, he felt the ground trembling beneath his feet. It rumbled and shook as though a distant train were passing, and yet there was none due now, for Mr. Nestor had just left one, and another would not arrive for an hour. "That's queer," mused Mary's father. "If I didn't know to the contrary, I'd say that sounded like heavy guns being fired from a distance, or else blasting. It seems to come from the Swift place," he went on. "I wonder what they're up to in there." Suddenly the rumbling became more pronounced, and mingled with it, in the dusk of the evening, were the shouts of men. "Look out!" some one cried. "She's going for the fence!" A second later there was a cracking and straining of boards, and the fence near Mr. Nestor bulged out as though something big, powerful and mighty were pressing it from the inner side. But the fence held, or else the pressure was removed, for the bulge went back into place, though some of the boards were splintered. "Have to patch that up in the morning," called another voice, and Mr. Nestor recognized it as that of Tom Swift. "What queer doings are going on here?" mused Mary's father. "Have they got a wild bull shut up in there, and is he trying to get out? Lucky for me he didn't," and he hurried on, the rumbling noise become fainter until it died away altogether. That night, after his supper and while reading the paper and smoking a cigar, Mr. Nestor spoke to his daughter. "Mary, have you seen anything of Tom Swift lately?" "Why, yes, Father. He was over for a little while the other night, but he didn't stay long. Why do you ask?"