The gallant horse seemed to gather every muscle to a high tension when he reached the verge of the chasm.
He bounded high in the air.
For an instant the horse and rider were poised there.
It was a brave effort.
But it failed.
Three-fourths of the distance was covered.
Then down the animal plunged into the abyss.
As they sunk out of sight Jack whirled the wheel around and applied the air brake.
The Terror barely had time to swing around to avoid the edge of the chasm, and a cloud of dirt and dust flew up from beneath her wheels.
She quickly paused.