"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."
"Dare you do it?" cried the old professor, hope shining in his face.
"Try me and see."
The professor quickly prepared a piece of silk, kept on hand to repair breaks in the bag. It was coated with a very strong and fresh cement. The silk was to be inserted in the tear made by the eagles, when it would at once harden and prevent the further escape of gas.
Mark made ready for the perilous ascent. He took off his coat, and removed his shoes so his feet could better cling to the frail-looking though strong cords.
"Slow down the ship!" commanded the captain. "Now, Mark, try! I hope you succeed! Move cautiously. You don't want to lose your life!"
Mark said nothing. He grasped the piece of oiled silk, coated with the cement, in his teeth, clinching it by a strip that was free from the sticky substance. Then he stood on the rail of the Monarch and began his climb aloft. Surely few ascents were made under such fearful conditions. The airship was now more than a mile above the earth. One false step and the boy would plunge into eternity. Nothing could save him.
Up and up he went, testing every cord and mesh before he trusted his weight to it. On and on he advanced. The frail gas bag swayed in the wind that was springing up. It seemed like a thing alive.