can destroy
matter at a distance, they are afraid that we could find its secret too
easily, and block it, for they don't think it is a weapon, and it is
evidently slow in action."

"Then it isn't what I thought it was," muttered Arcot.

"What did you think it was?" asked his father.

"Er--tell you later. Go on with the account."

"Well, to continue. We have not been idle. Following your suggestion, we
built up a large ray screen apparatus, in fact, several of them, and
carried them in ships to different parts of the world. Also some of the
planets, lest they start dropping worlds on us. They are already in
operation, sending their defensive waves against the Heaviside layer.
Radio is poor, over any distance, and we can't call Venus from inside
the layer now. However, we tested the protection, and it works--far more
efficiently than we calculated, due to the amazing conductivity of the
layer.

"If they intend to attack in that way, I suspect that it will be soon,
for they are ready now, as we discovered. An attack on their fort was
met with a ray screen from the fort.

"They fight with a wild viciousness now. They won't let a ship get near
them. They destroy everything on sight. They seem tremendously afraid of
that apparatus of yours. Too bad we had no more."

"We will have--if you will let me get to work."

They went to the ship, and entered it. Arcot senior did not follow, but
the others waited, while the ship left Earth once more, and floated in
space. Immediately they went into the time-field.

They worked steadily, sleeping when necessary, and the giant strength of
Torlos was frequently as great an asset as his indefatigable work. He
was learning rapidly, and was able to do a great deal of the work
without direction. He was not a scientist, and the thing was new to him,
but his position as one of the best of the secret intelligence force of
Nansal had proven his brains, and he did his share.

The others, scientists all, found the operations difficult, for work had
been allotted to each according to his utmost capabilities.

It was still nearly a week of their time before the apparatus was
completed to the extent possible, less than a minute of normal time
passing.

Finally the unassembled, but completed apparatus, was carried to the
laboratory of the cottage, and word was sent to all the men of Earth
that Arcot was going to give a demonstration of the apparatus he hoped
would save them. The scientis