Then he picked Mart up and put him over his shoulder.

At once the boy began to scream for help.

"Shut up!" growled Porler.

For reply Mart screamed louder.

Then Porler threw him down, poured some chloroform he had in a bottle on his handkerchief and applied it to Mart's nose.

The boy struggled vainly for a few minutes and then became limp in his arms.

"Ah, that did the business," Porler murmured to himself. "Glad I brought the chloroform along."

He took Mart to his carriage and placed him inside, covering him with several robes.

When Mart came to his senses he found himself in a little room. The door was locked and the one window was nailed up tightly. He was a close prisoner.

The boy had been placed on a cot in the corner, and now sat up and gazed around in bewilderment.

"Where am I?" he thought.

Then the full realization of what had happened burst upon the boy, and he gave way to tears.

"That bad man! What does he intend to do with me?"

Hour after hour went by and no one came to Mart.

There was a pitcher of water in the room and a loaf of bread, both on a stand close at hand.

He drank some of the water, but could not eat.

He knew it was night. Slowly the hours dragged by until morning.

Not long after this the door was unlocked and Porler came into the room.

"Awake, are you?" he said. "Hope you slept well."

"You monster!" Mart cried. "What are you going to do with me?"

"I'll tell you. I am going to make you promise on your bended knees that you will travel with me as you used to do, and obey all my commands."

"I'll never promise anything like that," exclaimed Mart, recoiling with horror.

"You will, or else-" The old balloonist paused.

"Or else what?"

"I will keep you here, and starve you into submission."

CHAPTER x.x.xIII.-LEO TO THE RESCUE.

Leo's first care, after leaving the hospital, was to ask about Mart.

He was astonished to learn at the hotel at which the party was stopping that nothing had been seen of the lad since the balloon had left the exhibition grounds.

Greson had gone for the balloon late the day before.

"Found the balloon all right, but didn't see a single trace of the boy,"

said the a.s.sistant.

"That is queer," mused Leo. "Can it be that he tumbled down in some out-of-the-way place and was killed?"

He at once learned the course the balloon had taken, and then got a buggy and horse and went over every inch of the ground.

A little later he found himself at the spot where the balloon had come down.

He walked around in much perplexity.

If Mart had escaped injury, where was he?

"All this must be Porler's work," said the young gymnast to himself. "I would just like to come across that man."

Satisfied that nothing was to be gained by remaining near the woods, Leo started back to the road.

In doing this he came across the bottle which had contained the chloroform Porler had used.

He picked up the bottle and smelled of what remained in it.

"My gracious!"

Like a flash the truth burst upon him.

"It's that rascal's work! He fired on me, and then came out here after Mart. He has abducted the boy!"

As we know, Leo was partly right and partly wrong.

The young gymnast realized that if he was to act he must do so without delay.

It made him very angry to think of the young lad being in the old balloonist's power.

That he would ill-use Mart he felt certain.

From where he had found the bottle Leo traced Porler's footsteps to the carriage.