re lost!"

"You are right!"

For a moment there was a doubt. Then the sticky stuff adhered to the
silk bag, and the patch was made fast. A shout from Washington in the
engine room told that the gas had ceased to rush out. Mark had
succeeded.

Washington hastened to turn the gas generator to half speed. Before he
could do so, however, there had been a great increase in the volume of
vapor in the bag, caused by the sudden stopping off of the vent. Up shot
the airship, the accumulation of gas lifting it higher from the earth.
So suddenly did it shoot up, from having been almost at rest, that there
was a tremor through the whole craft.

"Look out, Mark!" cried Jack. He looked up to where his comrade clung to
the netting.

"Hold fast! We'll stop the ship in a second," exclaimed the captain.

But it was too late. The sudden rising of the craft had shaken Mark's
hold, which was not of the best at any time, since the gas bag was a
yielding surface to lean against.

The next instant the boy, vainly clutching the air for some sort of grip
for his hands, toppled over backward. His feet slid from the meshes of
the net, and he plunged downward toward the earth, more than a mile
below!

CHAPTER IX

THE FROZEN NORTH REACHED

"He'll be killed!" shouted Jack.

"He's a goner!" yelled Washington, looking up from the engine room
window.

The old professor groaned and shut his eyes. He did not want to see the
boy fall.

Bill and Tom, with old Andy Sudds, had been watching Mark at his
perilous task, standing directly beneath him. Andy was the closer. He
leaned quickly backward when he saw what had happened.

Mark's body, turning over in its descent, was at the ship's side. Out
shot the hands of the old hunter. His fingers were curved like the
talons of an eagle. The long arms seemed to reach a great distance, and
then, just as it seemed that Mark would plunge downward to his death,
Andy grasped and held him.

"There!" exclaimed the hunter. "That was a close call, my boy!"

Mark did not answer. The fearful danger he had been saved from had so
frightened him that he became partially unconscious.

"Is he dead?" faltered Jack.

"He has only fainted," answered Amos Henderson. "I'll soon bring him
around."

The inventor hurried into the cabin and came out with some liquid in a
glass. This he placed to Mark's lips and soon the color came back into
the pale cheeks.

"What happened? Where am I?" asked the boy, sit