DANGER!

These walls may fall on you any moment. One leg
already broken here today. Keep out.

SAFETY FIRST!

Bob had just finished the lettering when a big automobile came purring
along in front of the ruined building. The chauffeur was in uniform. The
big man inside looked almost lost among the cushions, so roomy was the
machine. At a word from him, the car slowed down, and he scanned the
ruins sharply. Bob knew him in a moment for Bruce, the great mill owner,
one of the richest men in the city.

"Hello, what's this? What's this?" Bruce stood up in the car when the
little group on the steps caught his eye. In a twinkling he was out of
the automobile and bending over the groaning boy, while Bob and George
and Betty told him what had happened.

"Tut, tut!" snapped the great man whose mills gave work to thousands of
men, the twins' father among them. "This won't do at all! If the doctor
won't come to him, we must get him to the doctor." Pushing aside the
chauffeur, he lifted Chance into the car and on to the deep, comfortable
cushions as easily as if he had been a child of two instead of a lad of
twelve and big for his age.

"Now, jump in, the rest of you," he said, "and we'll take him over to
Doctor MacArthur's."

Betty climbed in and George followed. The chauffeur took his seat and
looked around at Bob, waiting. "What's the matter now?" asked Bruce,
impatiently, as Bob lingered on the step.

"It's those walls," answered the boy. "I hate to leave them in that
shape--somebody else will be getting hurt just as Chance did. I'd better
put up the sign. You folks go on, please, and I'll follow on foot."

The mill owner shook his head. "Put up your sign and come along. We'll
wait."

Bruce looked sharply at Bob's sign as the boy nailed it up in place, but
said nothing. Bob climbed into the waiting automobile, and the big
machine rolled smoothly, silently to the doctor's office.

Doctor MacArthur, surgeon's case in hand, came out. He was a little gray
man--gray-haired, dressed in a gray suit, with keen gray eyes that
seemed to take in everything at once.

"Who put those splints on?" He jerked out the words like a pistol shot.

"I did," said Bob, reddening; for the doctor's tone made him feel that
he must have bungled his work.

Swiftly the doctor bared the leg and laid a deft finger on the exact
spot of the break. "Simple fracture," was his verdict. "Bone