n surveyed the world only through the
glass windows at each side of her head and in front. Her air-tube entered
her helmet at the back. Two men in one of the boats were to keep the
young girl diver supplied with oxygen by pumping fresh air down through
this tube.

A moment later Captain Jules stood rigged in the same costume as Madge.

"Steady, my girl," Captain Jules warned her.

"Aye, aye, Captain," returned Madge quietly, "I'm ready. Let us go down
together to the bottom of the bay."

"Pump away," ordered the captain.

There was a splash on the surface of the clear water, a long-drawn gasp
from Madge's friends; then a few bubbles rose. Rapidly, skillfully,
Madge's tenders played out her life and pipe lines, and Madge Morton
disappeared from the world of men. Captain Jules made his plunge a few
seconds in advance of his companion.

In the boat where Tom Curtis and Phyllis Alden sat there was a
breathless, intense silence. The boy and girl happened to be in the boat
with the men who were looking out for the welfare of Captain Jules.
Philip Holt was with Madge's tenders.

Phyllis knew that there was but one way in which she could follow her
chum's course below the surface of the water. She could watch her life
and air lines. Captain Jules had made it plain to Phyllis that all the
time the diver is under water small ripples will appear near his air
line. These bubbles are caused by the air that the diver breathes out
from the valve in the side of his diving helmet.

Phyllis watched the lines doggedly. Captain Jules was to keep Madge under
water only about fifteen or twenty minutes, but at that a minute may
appear longer than an hour.

Suddenly Phyllis Alden discovered that the man who was tending Madge's
air pump seemed to be working less vigorously. He pumped unevenly. Once
he swayed, as though he were about to fall over in his seat.

In a second it flashed over Phyllis that the man was ill. He was a
strong, red-faced individual, but his face turned to a kind of ghastly
pallor. It was all so quick that Phil had no time to speak from her boat.
Philip Holt, who was in the same boat with the man, grasped the situation
as quickly as Phyllis did. With a single motion he took the tender's
place at the air-pump. Phil saw that he was pumping away with vigor.

At this moment Phil turned to speak to Tom Curtis. "Tom, how long have
they been under the water?" she whispered.

"Ten minutes," returned Tom, glancing hast