* * *

I had seen the _Comet_ before, but never so close. With a hull of
shining helio-beryllium--the new light, inactive alloy of a metal and a
gas--the ship was a cylinder about twenty feet long, by fifteen in
diameter, while a pointed nose stretched five feet farther at each end.
Fixed in each point was a telescopic lens, while there were windows
along the sides and at the top--all made, Garth informed us, of another
form of the alloy almost as strong as the opaque variety. Running
half-way out each end were four "fins" which served to apply the power
driving the craft. A light inside showed the interior to be a single
room, ten feet high at the center of its cylindrical ceiling, with a
level floor.

"How do you know this will be the bottom?" I asked, giving the vessel a
shove to roll it over. But it would not budge. Garth laughed.

"Five hundred pounds of mercury and the disintegrators are under that
floor, while out in space I have an auxiliary gravity engine to keep my
feet there."

"You see, since your mathematical friends derived their identical
formulas for gravity and electromagnetism, my job was pretty easy. As
you know, a falling body follows the line of least resistance in a field
of distortion of space caused by mass. I bend space into another such
field by electromagnetic means, and the _Comet_ flies down the track.
Working the mercury disintegrators at full power, I can get an
acceleration of two hundred miles per second, which will build up the
speed at the midpoint of my trip to almost four thousand times that of
light. Then I'll have to start slowing down, but at the average speed
the journey will take only six months or so."

* * * * *

"But can anyone stand that acceleration?" Kelvar asked.

"I've had it on and felt nothing. With a rocket exhaust shoving the
ship, it couldn't be done, but my gravitational field attracts the
occupant of the _Comet_ just as much as the vessel itself."

"You're sure," I interrupted, "that you have enough power to keep up the
acceleration?"

"Easily. There's a two-thirds margin of safety."

"And you haven't considered that it may get harder to push? You know the
increase of mass with velocity. You can't take one-half of the
relativity theory without the other. And they've actually measured the
increase of weight in an electron."

"The electron never knew it; it's all a matter of reference points. I
can't fo