on joined zealously in the grim battle with the abyss--for battle
it soon proved to be. Only in places was the subterranean river
shallow and easy to wade. More often it foamed in wild fury down steep
rapids, to fling itself over ledges into black pools; or, worst of
all, it swirled deep and arrowy-swift between fanged rocks where the
channel narrowed.

Wading, swimming, leaping from rock to rock, scrambling up and down
the steep precipice foot, creeping along narrow shelves,--stubbornly
the explorers fought their way deeper through that wild passage.
Chilled by the icy waters and bruised by many a slip on loose stones
and wet, water-polished rocks, ever they carried the line of levels
down alongside the torrent, crossing over and back from side to side,
twisting and turning with the twists and bends of the chasm. And at
every stand Blake jotted down the rod readings in his half-soaked book
with his pencil and figured the elevation of each turning point before
"pulling up" his instrument to move on downstream to the next "set
up."

At the end of every half hour he fired a single shot to signal their
progress in the depths to the watchers above. But never once did he
stop to look up for the flag. Occasionally he was required to help
Ashton through or over some unusually difficult passage. For the most
part, however, each fought his own way. The odds were not altogether
in favor of the older man. He was hampered by the care of the
instrument, which must be shielded from all blows or falls. The rod,
on the contrary, served as a staff and support to Ashton, alike in the
water and on the rocks.

Some time before sunset the waning light in the canyon bottom became so
dim that Blake was compelled to cease work. He took a last reading on
a broad shelf of rock well above the surface of the water, joined
Ashton on the shelf, and began firing the revolver at five-minute
intervals. After the fifth shot he at last perceived the white dot of
the flag far above on the opposite brink of the chasm. He fired two
shots in quick succession, and calmly sat down to open one of the
soaked packages of food.

Ashton did not wait to be bidden to supper. He fell to on the food and
ate ravenously. Blake did not check him, though he himself took little
and carefully gathered up and returned to the package every scrap of
food left at the end of the meal. As Ashton lay back on the rock he
squirmed from side to side and groaned. His bruises were