ailed on
undisturbed, our torpedoes being exhausted. Several investigator
machines sent out for the purpose soon discovered the secret of the
force-screen, and while being destroyed, were able to send back signals
up to the moment of annihilation.

A few investigators thrown into the heat beam of the enemy reported it
identical with ours, explaining why they had been prepared for this form
of attack.

Signals were being radiated from the remaining fifty, along a beam.
Several investigators were sent along these beams, speeding back at
great acceleration.

Then the enemy reached Earth. Instantly they settled over the Colorado
settlement, the Sahara colony, and the Gobi colony. Enormous, diffused
beams were set to work, and we saw, through the machine-screens, that
all humans within these ranges were being killed instantly by the
faintly greenish beams. Despite the fact that any life-form killed
normally can be revived, unless affected by dissolution common to living
tissue, these could not be brought to life again. The important cell
communication channels--nerves--had been literally burned out. The
complicated system of nerves, called the brain, situated in the
uppermost extremity of the human life-form, had been utterly destroyed.

Every form of life, microscopic, even sub-microscopic, was annihilated.
Trees, grass, every living thing was gone from that territory. Only the
machines remained, for they, working entirely without the vital chemical
forces necessary to life, were uninjured. But neither plant nor animal
was left.

The pale green rays swept on.

In an hour, three more colonies of humans had been destroyed.

Then the torpedoes that the machines were turning out again, came into
action. Almost desperately the machines drove them at the Outsiders in
defense of their masters and creators, Mankind.

The last of the Outsiders was down, the last ship a crumpled wreck.

Now the machines began to study them. And never could humans have
studied them as the machines did. Scores of great transports arrived,
carrying swiftly the slower moving science-investigators. From them came
the machine-investigators, and human investigators. Tiny investigator
spheres wormed their way where none others could reach, and silently the
science-investigators watched. Hour after hour they sat watching the
flashing, changing screens, calling each other's attention to this, or
that.

In an incredibly short time the bodies of the