On and on they came in spite of the number among them that were killed.  Every one on the ship, except Washington, who had to attend to the engines, was firing.  The birds never stopped or swerved from their course.

Then with a rush and roar, a flapping of wings that sounded like thunder, and shrill cries and screams that almost drowned the noise of the guns, the eagles surrounded the Monarch.  They struck at it with their talons.  They opened wide their sharp beaks and snapped at the wood and iron.

Some of the fierce birds even attacked the men, and boys, and were beaten off with the butts of the rifles.  Others of the eagles rose higher in the air and struck at the oiled silk bag.  At first the yielding surface offered no resistance and was not damaged.  Then one fierce bird, with wide-opened beak, struck at the thin cloth and tore a hole in it as large as a man’s hand.

The sudden settling of the airship told that something was wrong.  Then the professor, glancing aloft, saw what had happened, and hastened to his helper.

“Quick, Washington!” he shouted.  “Start the gas generator at full speed!  We must pump lots of the gas in to keep us afloat!  We are in great danger!”

“Why not try the machine gun on the eagles?” shouted Jack.

“Good idea!” exclaimed the inventor.  “You two boys work it!”

At last the eagles, alarmed by the number killed, and frightened by the noise of the guns and the shots, halted in their rushes at the airship.  Some of the wounded ones wheeled away.  Then others followed until, finally, the whole colony of birds sailed off.

“There they go!” cried Jack.

“Yes, but I fear too late to do us any good,” spoke the professor.  “The airship is slowly settling.”

“Can’t it be fixed?” asked Mark.

“I suppose I could let it down to earth and patch up the hole, but I fear to do so,” answered the inventor.  “The Monarch is not under control, and if I attempt to make a landing I may smash her all to pieces.  She may settle down until within a few hundred feet of the earth and then plunge like a meteor.  We would all be killed then.”

“Is there no other way?” asked Jack.

“None, unless we could patch up the hole in the gas bag while we are up aloft.  I can hold the ship there for a while yet.  Another reason why I do not want to land is that we are over a thickly settled portion of the state now, and if I go down to earth we will be surrounded by a curious crowd that will delay us.”

“Is that netting strong?” asked Mark, suddenly, pointing to the cords that confined the gas bag.

“Two strands would support a man’s weight,” said Mr. Henderson.

“And have you anything to mend the silk bag with?” went on the boy.

“Yes, but why do you ask?”

“Because,” answered Mark, “if you’ll let me I’ll climb up and mend the hole the eagle made.”