flying along high, and at great speed, for Tom wanted to make all the distance he could, to get out of Siberia the more quickly. They had had a fair passage so far, and were congratulating themselves that they would soon be in civilization again.
Suddenly, Mr. Damon, who had been on the after deck, taking observations through a telescope, came running forward, crying out:
"Tom! Tom! What is that water dripping from the back part of the airship?"
"Water?" exclaimed Tom. "No water is dripping from there."
"Come and look," advised Mr. Damon.
The young inventor raced back with him. He saw a thin, white stream trickling down from the lower part of the craft. Tom sniffed the air suspiciously.
"Gasolene! It's gasolene!" he cried. "We must have a leak in the supply tanks!"
He dashed toward the reserve storeroom, and at that moment, with a suddenness that was startling, the motor stopped and the Falcon lurched toward the earth.
