higher before
they continued the work, beginning with the highest blocks that were
loose, and having the satisfaction of seeing the heaviest block there,
which took two or three to move it, go roaring down, sweeping with it
others nearly as big.

They worked for fully half-an-hour, to look down at last in wonder to
see the great success of their work, the gap being piled high, and,
leaving horses out of the question, forming a barrier that it would be
hard work for an active man to climb.

"Stop now," said the doctor, and all gladly rested, to stand wiping the
perspiration from their streaming faces. "No horses can possibly pass
by here."

"Mind! Quick! Down with you!" shouted Wilton, and as he spoke an arrow
struck against the rocky wall close to his head and glanced off, to fly
far away along the gulch.

CHAPTER FIFTY TWO.

THE PROGRESS OF THE PLAN.

"A narrow escape," said Bourne, and another arrow passed over without
injury to any one present, for the simple reason that all had obeyed the
warning and dropped behind the nearest cover.

"Be on the alert," cried the doctor from the other side. "That means
they are coming back."

"And Griggs was to have been with us by this time to help in the fight.
Father, this looks bad."

The doctor met his son's eyes, and then turned to look in the direction
from which their companion would be bound to arrive if he had managed to
escape over the terraces to make for the gully.

"Don't judge rashly, my boy," said the doctor. "He has had very little
time yet.--Are you all ready for the enemy?"

"Yes," came back quickly enough; but there was no enemy visible.

"Could you see who sent that arrow, Wilton?"

"No, but there are two ponies grazing up yonder. I fancy they must
belong to the last Indians we saw come by."

"It looks like it, as only two shots have come. But we shall have the
whole body coming back soon."

"Close upon a hundred," said Wilton, "and we are five."

"Yes, five, in a strong fortress, with modern weapons against
instruments of barbarism; and what is more, we have dealt the enemy such
a blow as will take them long enough to get over."

"But I wish we were all together, father, instead of being divided.
Wouldn't it be better if we tried to get to them?"

"No," said the doctor quietly. "We are quite right here for the
present, and perhaps we shall have our side strengthened soon by the
coming of friend Griggs."

"Ah!" sighed Chris