een impossible without them.
The explanation as he gave it to Stel Felso Theu, foretold the uses to
which it might be put.

"As a weapon," he pointed out, "its most serious fault is that it takes
a considerable time to pump in the power needed. It has here,
practically the same fault which the artificial matter had on your
world.

"As I see it, the ray is actually a directed gravitational field.

"Now here is one thing that makes it more interesting, and more useful.
It seems to defy the laws of mechanics. It acts, but there is no
apparent reaction! A small ship can swing a world! Remember, the field
that generates the attraction is an integral, interwoven part of the
mesh of Space. It is created by something outside of itself. Like the
artificial matter, it exists there, and there alone. There is reaction
on that attractive field, but it is created in Space at that given
point, and the reaction is taken by all Space. No wonder it won't move.

"The work considerations are fairly obvious. The field is built up. That
takes energy. The beam is focused on a body, the body falls nearer, and
immediately absorbs the energy in acquiring a velocity. The machine
replenishes the energy, because it is set to maintain a certain
energy-level in the field. Therefore the machine must do the work of
moving the ship, just as though it were a driving apparatus. After the
beam has done what is wanted, it may be shut off, and the energy in the
field is now available for any work needed. It may be drained back into
power coils such as ours for instance, or one might just spend that last
iota of power on the job.

"As a driving device it might be set to pull the entire ship along, and
still not have any acceleration detectable to the occupants.

"I think we'll use that on our big ship," he finished, his eyes far away
on some future idea.

"Natural gravity of natural matter is, luckily, not selective. It goes
in all directions. But this artificial gravity is controlled so that it
does not spread, and the result is that the mass-attraction of a mass of
matter does not fall off as the inverse square of the distance, but like
the ray from the parallel beam spotlight, continues undiminished.

"Actually, they create an exceedingly intense, exceedingly small
gravitational field, and direct it in a straight line. The building up
of this field is what takes time."

Zezdon Afthen, who had a question which was troubling him, looked
anxiously