They gave Tom more medicine, rubbed his arms and legs, and held ammonia under his nose.  Slowly he opened his eyes, and in a faint voice asked: 

“Where—­am—­I?”

“In your own house,” replied Mr. Damon, cheerfully.  “How do you feel?”

“I’m—­all—­right—­now,” said Tom slowly.  He, felt his strength coming gradually back, and he remembered what had happened, though he did not yet know how he had been saved.  The doctor came in at this moment, with a small medical battery, which completed the restorative work begun by the others.  Soon Tom could sit up, though he was still weak and rather sick.

“Who brought me out?” he asked, when he had briefly told how the accident occurred.

“Koku did,” replied Mr. Damon.  “I guess none of the rest of us could have lifted the iron shaft from your legs.”

“It’s queer how that fell,” said Tom, with a puzzled look on his face.  “I didn’t hit it hard enough to bring it down.  Beside, I had it tied to nails, driven into the wall, to prevent just such an accident as this.  I must see about it when I get well.”

“Not for a couple of days,” exclaimed the doctor grimly.  “You’ve got to stay in bed a while yet.  You had a narrow escape, Tom Swift.”

“Well, I’m glad I went to Giant Land,” said the young inventor, with a wan smile.  “Otherwise I’d never have Koku,” and he looked affectionately at the big man, who laughed happily.  In nature Koku was much like a child.

Mr. Swift came home a little later, and Ned Newton called, both being very much surprised to hear of the accident.  As for Eradicate, the poor old colored man was much affected, and would have sat beside Tom’s bed all night, had they allowed him.

Our hero recovered rapidly, once the fumes of the gas left his system, and, two days later, he was able to go out to the shop again.  At his request everything had been left just as it was after he had been brought out.  Of course the fumes of the gas were soon dissipated, when the door was opened, and the acids, after mingling and giving off the vapor, had become neutralized, so that they were now harmless.

“Now I’m going to see what made that shaft fall,” said Tom to Ned, as the two chums walked over to the bench where the young inventor had been working.  “The tap I gave it never ought to have brought it down.”

Together they examined the thin, but strong, cords that had been passed around the shaft, having been fastened to two nails, driven into the wall.

“Look!” cried Tom, pointing to one of the cords.

“What is it?” asked Ned.

“The strands were partly cut through, so that only a little jar was enough to break the remaining ones,” went on Tom.  “They’ve been cut with a knife, too, and not frayed by vibration against the nail, as might be the case.  Ned, someone has been in my shop, meddling, and he wanted this shaft to fall.  This is a trick!”