She appeared to be making the descent safely, when there was a sudden change. The earth seemed to slip out from under the broad caterpillar belts, and then the tank moved more rapidly.
"Tom, we're turning over!" shouted Ned. "We're capsizing!"
Chapter XIV
The Ruined Factory
Only too true were the words Ned Newton shouted to his chum. Tank A was really capsizing. She had advanced to the edge of the gully and started down it, moving slowly on the caterpillar bands of steel. Then had come a sudden lurch, caused, as they learned afterward, by the slipping off of a great quantity of shale from an underlying shelf of rock.
This made unstable footing for the tank. One side sank lower than the other, and before Tom could neutralize this by speeding up one motor and slowing down the other the tank slowly turned over on its side.
"But she isn't going to stop here!" cried Ned, as he found himself thrown about like a pill in a box. "We're going all the way over!"
"Let her go over!" cried Tom, not that he could stop the tank now. "It won't hurt her. She's built for just this sort of thing!"
And over Tank A did go. Over and over she rolled, sidewise, tumbling and sliding down the shale sides of the great gully.