Along the pleasant country roads on a fine day in April rode Tom Swift on his way to Mansburg to register the letter. As he descended a little hill he saw, some distance away, but coming toward him, a great cloud of dust. "Somebody must be driving a herd of cattle along the road," thought Tom. "I hope they don't get in my way, or, rather, I hope I don't get in theirs. Guess I'd better keep to one side, yet there isn't any too much room." The dust-cloud came nearer. It was so dense that whoever or whatever was making it could not be distinguished. "Must be a lot of cattle in that bunch," mused the young inventor, "but I shouldn't think they'd trot them so on a warm day like this. Maybe they're stampeded. If they are I've got to look out." This idea caused him some alarm. He tried to peer through the dust-cloud, but could not. Nearer and nearer it came. Tom kept on, taking care to get as far to the side of the road as he could. Then from the midst of the enveloping mass came the sound of a steady "chug-chug." "It's a motor-cycle!" exclaimed Tom. "He must have his muffler wide open, and that's kicking up as much dust as the wheels do. Whew! But whoever's on it will look like a clay image at the end of the line!" Now that he knew it was a fellow-cyclist who was raising such a disturbance, Tom turned more toward the middle of the road. As yet he had not had a sight of the rider, but the explosions of the motor were louder. Suddenly, when the first advancing particles of dust reached him, almost making him sneeze, Tom caught sight of the rider. He was a man of middle age, and he was clinging to the handle-bars of the machine. The motor was going at full speed. Tom quickly turned to one side, to avoid the worst of the dust. The motor-cyclist glanced at the youth, but this act nearly proved disastrous for him. He took his eyes from the road ahead for just a moment, and he did not see a large stone directly in his path. His front wheel hit it, and the heavy machine, which he could not control very well, skidded over toward the lad on the bicycle. The motor-cyclist bounced up in the air from the saddle, and nearly lost his hold on the handle-bars. "Look out!" cried Tom. "You'll smash into me!" "I'm--I'm--try--ing--not--to!" were the words that were rattled out of the middle-aged man. Tom gave his wheel a desperate twist to get out of the way. The motor-cyclist tried to do the same, but the machine he was on appeared to want matters its own way. He came straight for Tom, and a disastrous collision might have resulted had not another stone been in the way. The front wheel hit this, and was swerved to one side. The motor-cycle flashed past Tom, just grazing his wheel, and then was lost to sight beyond in a cloud of dust that seemed to follow it like a halo. "Why don't you learn to ride before you come out on the road!" cried Tom somewhat angrily. Like an echo from the dust-cloud came floating back these words: