couts were hidden under the load.

"This is a loyal peasant--and one of our best spies!" said Stepan. "The
Austrians trust him because he seems to be so stupid, and so we can pass
through the line of sentries to the south. If we tried to walk we would
be turned back. He is taking these potatoes to the advanced positions of
the Austrians."

"That's fine, only I'd like to know what we are going to do after we
have passed the sentries! We shall be within two Austrian lines even
then, shan't we?"

"We certainly shall--but we shan't stay there!"

"Oh, I give it up! I never was good at guessing riddles, anyhow!"

"Sh-h! We can't tell when we're near the sentries, and we'd better keep
quiet now."

After a little time the cart stopped with a jolt, and they heard the
peasant driver, as he seemed to be, exchanging rough jests with the
sentries. Then there was a grounding of arms, and they passed on. For
perhaps fifteen minutes they continued to jolt along, and for the first
time Dick was glad, despite the heat, that he was wearing such thick
garments, since they saved him, he was convinced, a good many bruises.
He decided that that must be the reason they had worn them. Then the
cart stopped and the driver began to make a way for them to get out,
which they were glad to do.

"All right--good luck and good-night, Ivan!" said Stepan.

"And to you, good luck and the grace of God, Stepan Ivanovitch!" said
the driver. "There is nothing more that I can do?"

"No. Good-bye!"

The cart rumbled off, and Stepan turned off to the right. Dick asked no
questions, but went along, satisfied that the mystery must soon be
solved. And indeed it was. They were on level ground now, but soon they
began to descend, and found themselves in a rather wide ravine. There
was a sudden challenge: "Who goes there?" delivered in Servian!

"Kossovo!" answered Stepan.

"Pass," said the sentry, who was not in uniform, and carried a revolver
instead of a rifle.

And then, a few paces further on, they came to a strange mass covered
with canvas. A man stepped out of the shadow, flashing an electric torch
in their faces.

"Stepan? That is good!" he said.

Stepan went forward and drew off the canvas cover, and Dick saw what was
underneath--a monoplane, as he had guessed!

"That is a captured Austrian 'plane," said Stepan. "Now do you
understand? Are you willing to take the risk of flying in it with me?"

"I wouldn't miss it!" said Dick. "But I di