and exploded into coruscating, blinding energy. It could not
penetrate it. More energy lashed at the wall of blackness as the
operators within the sphere-fort turned in the energy of all the
generators under their control. The ground about the fort was a great
lake of dazzling lava as far as the eye could see, for the triple-ray
was releasing its energy, and the wall of black was releasing an equal,
and opposing energy!

"Stopped!" cried Arcot happily. "Now here is where we give them
something to think about. The magnet and the heat!"

He turned the two enormous forces simultaneously on the point where he
knew the fort was, though it was invisible behind the wall of black that
protected him. From his side, the energy of the spot where all the
system of Thett was throwing its forces, was invisible.

Then he released them. Instantly there was a terrific gout of light on
that wall of blackness. The ship trembled, and space turned gray about
them. The black wall dissolved into grayness in one spot, as a flood of
energy beyond comprehension exploded from it. The enormously strong
cosmium wall dented as the pressure of the escaping radiation struck it,
and turned X-ray hot under the minute percentage it absorbed. The
triple-ray bent away, and faded to black as the cosmic force playing
about it, actually twisted space beyond all power of its mechanism to
overcome. Then, in the tiniest fraction of a second it was over, and
again there was blackness and only the brilliant, blinding blue of the
cosmium wall testified to its enormous temperature, cooling now far more
slowly through green to red.

"Lord--you're right, Zezdon Afthen. I'm going to sleep," called Arcot.
And the ship was suddenly far, far away from Thett. Morey took over, and
Arcot slept. First Morey straightened the uninjured wall and ironed out
the dents.

"What, Morey, is the wall of Blackness?" asked Stel Felso Theu.

"It's solid matter. A thing that you never saw before. That wall of
matter is made of a double layer of protons lying one against the other.
It absorbs absolutely every and all radiation, and because it is solid
matter, not tiny sprinklings of matter in empty space, as is the matter
of even the densest star, it stops the triple-ray. That matter is
nothing but protons; there are no electrons there, and the positive
electrical field is inconceivably great, but it is artificial matter,
and that electrical field exerts its strain not in pulling and