ich they had taken
refuge, and knew the need of cautious approach. Mexicans do not lack
bravery, but both Obed and Ned were sure there would be a long delay.

"I think that all we've got to do for the present," said Obed, "is to
watch the woods in front of us, and see that none of them sneaks up near
enough for a good shot."

Nearly an hour passed, and they neither saw nor heard anything in the
forest. Then there was a rushing sound, a tremendous impact in front of
them and something huge bounded and bounded again among the bushes. It
was a great rock that had been rolled over the cliff above, in the hope
that it would fall upon them, but the arch of stone over their heads was
too deep. It struck fully five feet in front of them. Both were
startled, although they knew that they were safe, and involuntarily they
drew back.

"More will come," said Obed. "Just as one swallow does not make a
summer, one stone does not make a flight. Ah, there it is now!"

They heard that same rushing sound through the air, and a bowlder
weighing at least half a ton struck in front of their log. It did not
bound away like the first, but being so much heavier buried half its
weight in the earth and lay there. Obed chuckled and regarded the big
stone with an approving look.

"It's an ill stone that doesn't fall to somebody's good," he said. "That
big fellow is squarely in the path of anybody who advances to attack us,
and adds materially to our breastwork. If they'll only drop a few more
they'll make an impregnable fortification for us."

The third came as he spoke, but being a light one rolled away. The
fourth was also light, and alighting on the big one bounded back into
the alcove, striking just between Ned and Obed. It made both jump and
shiver, but they knew that it was a chance not likely to happen again in
a hundred times. The bombardment continued for a quarter of an hour
without any harm to either of the two, and then the silence came again.
Ned and Obed pushed the rock out of the alcove, leaving it in front of
them and now their niche had a formidable stone reinforcement.

"They'll be slipping up soon to look at our dead bodies," whispered
Obed, "and between you and me, Ned, I think there will be a great
surprise in Mexico to-day."

They lay almost flat and put the muzzles of their rifles across the log.
Both, used to life on the border, where the rifle was a necessity, were
fine shots and they were also keen of eye and ear.