l retreat toward the river. Moving cautiously from
tree to tree the Professor and John traveled as rapidly as possible in
the direction of the wagon, and the boys were commended for their
forethought in keeping the wagon in a hidden position while awaiting
their arrival.

"It looks as though we had outwitted them, at any rate for the time
being, and it will keep them back long enough to enable us to get a good
start, so hurry on as fast as possible. Make for the side of the hill
which I pointed out before. If they discover our absence, and can gather
their forces we may be able to use the precipitous side of the hill as a
protection. But remember, the river is our objective point."

No urging was needed. On the way the second stream or running brook was
crossed. Harry called to one of the boys: "Get some of the copper
kettles from the wagon and get some water. If we are held up at the hill
the yaks will need it, as well as ourselves." George and the boys
recognized the importance of it, and weak as the two rescued boys were,
they dragged the filled kettles to the wagon, and George fastened the
wooden covers on them.

Within ten minutes more the hill was reached. It was not high nor
difficult to mount, and at one point it seemed to spring up into a peak,
the southern side of the point presenting a steep outline. The boys saw
that on the side facing the river, which was less than a mile away, the
precipitous portion was formed by a wall of peculiar brownish-gray
rock.

Behind this rocky fortress the wagon was driven, and the first care of
Harry was to water the animals, as they had not been allowed to quench
their thirst on the way. They waited an hour or more for the appearance
of the Professor and John. George went out on a quest back over the
trail which they had just made, and almost reached the stream before he
caught sight of them lurking through the trees and shrubbery.

They were relieved to know that the wagon was in safety, and after the
stream was crossed the three delayed no longer, but hurried rapidly
forward and soon reached the wagon, to the great relief of Harry and the
boys.

"Let us haste to the river," was the Professor's hurried order, as he
came up, and the yaks were at once urged forward, but as he passed the
rocky wall, he cried out: "Wait, let us examine this first."

The boys knew that if, in such an emergency, he could call a halt, the
appearance of the rock would reveal something that mi