pressed steam was moving pistons up and down
like pump handles. The pistons communicated their motion to the big shaft
running aft along the keel to the stern, and the revolutions of the shaft
in turn produced the revolutions of the screw propelling the vessel
across the Atlantic.

Oilers holding oil cans and waste clambered in and out of the rotating
masses of iron with astounding sureness and boldness. To graze one of the
fly-wheels, or to step one inch within the unguarded circle of their
revolution, was to receive a deadly blow. Here was the heart and soul of
the vessel, the real modern miracle of strength, the like of which no age
in the past has been able to produce. An iron soul, a steely heart. It
was as if one were descending below earth into the glowing workshop of
Vulcan of old, the lame god, who did not demonstrate the full skill of
his divinity until our times.

Still deeper down went the descent, to where, from numerous shovels
handled by almost naked helots, coal was flying into the white heat under
the boilers, into a row of gaping jaws of fire. Frederick felt as if he
had reached the heart of a crater. It was a black shaft smelling of coal,
slag, and burning things. Apparently it was lighted only by the constant
opening of the furnace doors, spitting white heat. How was it possible
for such a conflagration to be contained in the _Roland's_ interior
without reducing the whole to ashes? What a conquest to fight such a sea
of fire, to keep it in check, and carry it through sea and storm; to
manage that it should carry itself three or six thousand miles in the
ocean in fair weather or foul, hidden away and absolutely innocuous.

Frederick panted for breath. The glowing heat of the abyss instantly
brought the perspiration pouring out on his face and neck. He was so
absorbed in the novelty of the impressions that he completely forgot he
was surrounded by water about twenty feet under the surface of the sea.
Suddenly, he became aware of Doctor Wilhelm's presence, and in the same
instant saw a man entirely naked stretched out like a corpse, a white
body on the black coal dust. The man had ceased to breathe.

In a second Frederick, now wholly the physician, had Doctor Wilhelm's
stethoscope in his hand and was listening to the man's heart. His mates,
blackened with coal from head to foot, were ceaselessly at work in the
engine's unremitting service, shovelling coal, opening the furnace doors,
and slamming them