es, as it is hard to breathe in this rarefied or thin
atmosphere."

The boys experienced some difficulty, but by avoiding any exertion were
not much bothered.

"Now we'll go down a bit," said the inventor, after the ship had whizzed
along for several miles above the masses of vapor. "I want to get an
idea where I am."

He turned some more wheels and levers. In a few minutes the ship was
again surrounded with a white cloud. Then it passed away, and the earth
came into view.

Suddenly the professor looked forward. He seemed to be gazing intently
at something.

"I wonder what that is?" he muttered. He took down a telescope and
adjusted it, peering forward with strained eyes.

"Can it be possible!" he exclaimed. Then he dropped the glass and
frantically signaled to the engine room.

"We must look out for ourselves!" he cried, "Come here, Andy Sudds!"

CHAPTER VIII

SURROUNDED BY EAGLES

There was a sudden tremor all over the airship as Washington, in the
engine room, in obedience to the signals, turned off the power. Then
sounded a hiss as the captain let some gas from the bag. The ship began
to sink toward the earth.

The black cloud that the professor had been gazing at came nearer. It
grew larger and seemed to be made up of a number of small moving
objects.

"Quick, Andy!" cried the old inventor. "We shall need your services
now!"

"What's the matter?" exclaimed the old hunter, as he hurried forward
with his gun in readiness.

"Eagles!" cried Amos Henderson.

"Eagles?"

"Yes! A whole flock of them. Just ahead! See that dark cloud! They are
coming this way! They think the ship is a rival bird and they will
attack it. Strong as the _Monarch_ is, the silk in the gas bag is
frail. If the birds tear that we will fall to the earth and be killed!
Use your gun! See if you can drive them off!"

Andy kneeled down on the forward part of the ship. He aimed at the black
mass, in which scores and scores of birds could now be seen. Then his
gun sent out fire and lead.

Bang! Bang! it spoke, and two birds dropped toward the earth. Again the
gun belched forth, and more of the eagles were killed. As fast as Andy
could pull the trigger he fired.

"We must all get guns!" cried the professor. "It is the only way to save
the ship! Come on, boys! You'll find weapons in the dining-room
lockers!"

Mark and Jack hurried after the rifles. The professor was greatly
excited. Bill and Tom came running forward. Th