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