t certain that some of them would ever see again, it was
not certain that some of them would recover. Absolute agony of the most
horrible kind awaited them. But the lighthouse had to be built. It is
easy to make a problematic sacrifice of life, it is hard to walk without
shrinking into a chamber of awful pain. From this ordeal these fourteen
men did not shrink.

"They were headed by Griffin, the old caisson foreman, who had a record
of having withstood the greatest pressure possible, a pressure of eight
and a half atmospheres. They went down at nine o'clock in the morning.
The pain must have been fearful, but they stuck to it to the end. One
man went through the air-lock and got food, returning to his comrades.
He had been down four hours, and his condition was so terrible that the
doctor ordered him to stay out of the lock.

"'I'm not that breed,' he said in a horrid whisper over his raw and
swollen throat, 'I'm goin' to see it through.'

"'Better keep away, my man,' the doctor said; 'I won't answer for what
will happen to you if you go back.'

"'I ain't no quitter,' was the answer. 'I'm a Boston wharf-rat, I am,
an' I stays wid de gang!'

"That doesn't sound like a heroic speech, Eric," said the first
lieutenant, "but it looks to me like it's the real stuff."

"It surely is," agreed the boy.

"He went back with a bite of food for all the men below and they worked
on steadily. By the way the stuff came up the pipe they must have worked
like demons. Every ear was keen for sign or sound of trouble, but the
afternoon wore on, the sand came hurtling from the pipe and the caisson
sank lower and lower.

"'How much further?' I asked Father, just as the evening was beginning
to draw in.

"'Not more than an inch or two,' he said triumphantly. 'I tell you
what, I envy those fellows down there. They're real men. I doubt if I'd
have the nerve to do it myself.'

"Suddenly there came a muffled roar below.

"'There it is!' cried the young scientist, and he made a bolt for the
air-lock.

"Father was not more than a second behind him, waiting only to make sure
of the point to which the structure had been sunk. The caisson was
within three quarters of an inch of the required depth!

"Meantime, down in the caisson, the feared disaster had occurred. The
gas had come up with a rush, almost like an explosion. In the green
glare of the candles, burning sulphur and hydrogen flames instead of
oxygen, the men were staggering, h