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.  The inventor rapidly handed out the guns.

In the meanwhile the ship was slowly settling toward the ground.  The captain hoped to get low enough to escape the onward rush of the big birds, but he had counted without the anger of the eagles.  They thought the airship was a rival in the realms of space and were determined to destroy it.