The cloud of highway dirt rolled along, making some progress toward Tom's house and the group of shops and other buildings surrounding it. But, as the lad had said, the dust did not move at all quickly in comparison to any of the speedy machines that might be causing it. And the cloud seemed momentarily to grow thicker and thicker. "I wonder if it could be a miniature tornado, or a cyclone or whirlwind?" and Tom spoke aloud, a habit of his when he was thinking, and had no one to talk to. "Yet it can hardly be that." he went on. "Guess I'll watch and see what it is." Nearer and nearer came the dust cloud. Tom peered anxiously ahead, a puzzled look on his face. A few seconds later there came from the midst of the obscuring cloud a voice, exclaiming: "G'lang there now, Boomerang! Keep to' feet a-movin' an' we sho' will make a record. 'Tain't laik we was a autermobiler, er a electricity car, but we sho' hab been goin' sence we started. Yo' sho' done yo'se'f proud t'day, Boomerang, an' I'se gwine t' keep mah promise an' gib yo' de bestest oats I kin find. Ah reckon Massa Tom Swift will done say we brought dis yeah message t' him as quick as anybody could." Then there followed the sound of hoofbeats on the dusty road, and the rattle of some many-jointed vehicle, with loose springs and looser wheels. "Eradicate Sampson!" exclaimed Tom. "But who would ever think that the colored man's mule could get up such speed as that cloud of dust indicates. His mule's feet must be working overtime, but he goes backward about as often as he moves forward. That accounts for it. There's lots of dust, but not much motion." Once more, from the midst of the ball-like cloud of dirt came the voice of the colored man: "Now behave yo'se'f, Boomerang. We'm almost dere an' den yo' kin sit down an' rest if yo' laik. Jest keep it up a little longer, an' we'll gib Massa Tom his telephone. G'lang now, Boomerang." The tattoo of hoofbeats was slowing up now, and the cloud of dust was not so heavy. It was gradually blowing away. Tom Swift walked down to the fence that separated the house, grounds and shops from the road. As he got there the sounds of the mule's progress, and the rattle of the wagon, suddenly ceased. "G'lang! G'lang! Don't yo' dare t' stop now, when we am most dere!" cried Eradicate Sampson. "Keep a-movin', Boomerang!" "It's all right, Eradicate. I'm here," called Tom, and when the last of the dust had blown away, the lad waved his hand to an aged colored man, who sat upon the seat of perhaps the most dilapidated wagon that was ever dignified by such a name. It was held together with bits of wire, rope and strings, and each of the four wheels leaned out at a different angle. It was drawn by a big mule, whose bones seemed protruding through his skin, but that fact evidently worried him but little, for now the animal was placidly sleeping, while standing up, his long ears moving slowly to and fro.