hen led them over to the vertical column which pierced the
middle of the floor. Enormous as the lateral had seemed, it appeared
puny in comparison with this monster of fabricated steel. Seaton
explained that the two verticals were many times stronger than the four
laterals, as the center of gravity of the ship had been made lower than
its geometrical center, so that the apparent motion of the vessel and
therefore the power of the bar, would usually be merely vertical.
Resting one hand caressingly upon the huge column, he exultantly
explained that these members were "the last word in strength, made up of
many separate I-beams and angles of the strongest known special steel,
latticed and braced until no conceivable force could make them yield a
millimeter."

"But why such strength?" asked the lawyer doubtfully. "This column alone
would hold up Brooklyn Bridge."

"To hold down the power-plant, so that the bar won't tear through the
ship when we cut her loose," replied Seaton. "Have you any idea how fast
this bird can fly?"

"Well, I have heard you speak of traveling with the velocity of light,
but that is overdrawn, isn't it?"

"Not very much. Our figures show that with this four-hundred-pound
bar"--pointing to the copper cylinder in the exact center of the inner
sphere--"we could develop not only the velocity of light, but an
acceleration equal to that velocity, were it not for the increase in
mass at high velocities, as shown by Einstein and others. We can't go
very fast near the earth, of course, as the friction of the air would
melt the whole works in a few minutes. Until we get out of the
atmosphere our speed will be limited by the ability of steel to
withstand melting by the friction of the air to somewhere in the
neighborhood of four or five thousand miles per hour, but out in space
we can develop any speed we wish, up to that of light as a limit."

"I studied physics a little in my youth. Wouldn't the mere force of such
an acceleration as you mention flatten you on the floor and hold you
there? And any sudden jar would certainly kill you."

* * * * *

"There can't be any sudden jar. This is a special floor, you notice. It
is mounted on long, extremely heavy springs, to take up any possible
jar. Also, whenever we are putting on power we won't try to stand up,
our legs would crimple up like strings. We will ride securely strapped
into those special seats, which are mounted the s