side.

The Professor's shot had entered his left eye, but the vitality of the
animal was such that he ran nearly a hundred feet before it took effect.

The yaks were soon rounded up. It is a wonder that more damage was not
done. Aside from the displacement of their bedding, and the ditching of
some of the cooking utensils, everything was found intact.

"That was a rather ill-advised adventure on our part. We should have
guarded our supplies; but I was as much to blame as you were. We must be
more careful in the future."

On every side the rough character of the land was more apparent, and it
was becoming more and more difficult to find tracks which were suitable
for the team.

"This matter of going further with our wagon is now getting to be a
serious problem. I think we should turn to the right and move in the
direction of home, or direct our course southeast toward the mountains
on the other side of South River."

"I think we have discovered enough on this trip," was Harry's
conclusion.

George assented, so that on the twelfth day of their journey the yaks
were directed towards home. For two days the travel was southeasterly,
through the most broken and tortuous paths, crossing innumerable small
streams and rivulets on their course. During this troublesome part of
their journey the weather was stormy, with numerous rains, some of them
so prolonged as to prevent traveling for hours, so that they made less
than twenty miles during that time.

[Illustration: _Fig. 4. DIAGRAM OF THEIR TRIP_]

On the third day, however, the ground became more level and less broken,
the sun appeared, and they felt happy at the thought of getting back
again.

Thus far in their wanderings they had kept their reckonings, as well as
they could without instruments, and that evening the chart was again
consulted, as usual. The drawing (Figure 4) shows how it looked with the
course of their journey.

When they started from the Cataract home at nine o'clock in the morning,
they made an observation of the sun, using a vertical pole so as to get
the exact direction of the falling shadow. A distant object was then
selected, a prominent tree, as far off as possible. The Professor had
prepared an adjustable bevel square, which was simply two legs hinged
together at one end, by means of a set screw, like a compass.

[Illustration: _Fig. 5. BEVEL SQUARE_]

"Now, boys, I want to show you how we can make a fairly good chart
simply by the us