he first
thing you know, you hear a sound inside your head like striking a match;
that's the crack, and then you can go on down as far as you please, and
you won't feel any more pain in your ears until you're coming up again;
then you get a reverse crack. They say it's the air working in and out
of your head. I don't know what it is, but I know some men's ears won't
crack, and those men can't never make divers."

"How deep can a diver go down?" I inquired.

The company smiled at this, and turned to Atkinson, who smiled back, and
then referred modestly to one of the deepest dives on record, one
hundred and fifty feet, made by himself some years before up the Hudson.
He had a pressure of six atmospheres on him at that depth, and could
stay down only twenty minutes. "I'll tell you about that some other
day," said he. "It's pretty near time now for me to be sweeping up this
coal."

Then, answering my look of surprise at the word "sweeping," he explained
how they lessen the weight of a sunken barge by first pumping out the
water in her, and then pumping out the coal. The same suction-pipe does
both, and will discharge thirty-five or forty tons of coal an hour, on a
chute which holds the coal while the water streams through. During this
operation the diver is down in the barge, moving the suction-end back
and forth, up and down--the "sweeping" in question--until no more coal
is left for its hungry mouth.

"We pump grain out of wrecks in the same way," said Atkinson, "tons and
tons of it! and they dry it in ovens and sell it. A man must look sharp,
though, and not get himself caught. We had a diver--he was new at the
business--who got his knee against the suction-pipe one day while he was
pumping coal, and it held him as if he was nailed there. He was so
scared he tore himself loose; but he had to rip a piece out of his suit
to do it. He stayed down, though, just the same."

[Illustration: DIVER STANDING ON SUNKEN COAL BARGE.]

"What!--with a hole in his suit?"

"That doesn't matter, as long as it's only in the leg. You see, the air
in the helmet presses down hard enough to keep the water below a man's
neck. But he mustn't bend over so as to let his helmet get lower than
the hole."

"I should say not!" put in Timmans.

"Why, what would happen if he did?"

"He'd be killed quicker than you can wink. The air from the helmet would
rush out at the hole, and he'd be crushed by the weight of the water."

I don't know wh