the blue terror above. They were riven and
torn. And through them black objects were falling. Some blazed as they
fell. They slipped into unthought maneuvers--they darted to earth
trailing yellow and black of gasoline fires. The air was filled with the
dread rain of death that was spewed from the gray clouds. Gone was the
roaring of motors. The air-force of the San Diego area swept in silence
to the earth, whose impact alone could give kindly concealment to their
flame-stricken burden.

Thurston's last control snapped. He flung himself flat to bury his face
in the sheltering earth.

* * * * *

Only the driving necessity of work to be done saved the sanity of the
survivors. The commercial broadcasting stations were demolished, a part
of the fuel for the terrible furnace across the bay. But the Naval radio
station was beyond on an outlying hill. The Secretary of War was in
charge. An hour's work and this was again in commission to flash to the
world the story of disaster. It told the world also of what lay ahead.
The writing was plain. No prophet was needed to forecast the doom and
destruction that awaited the earth.

Civilization was helpless. What of armies and cannon, of navies, of
aircraft, when from some unreachable height these monsters within their
bulbous machines could drop coldly--methodically--their diminutive
bombs. And when each bomb meant shattering destruction; each explosion
blasting all within a radius of miles; each followed by the blue blast
of fire that melted the twisted framework of buildings and powdered the
stones to make of a proud city a desolation of wreckage, black and
silent beneath the cold stars. There was no crumb of comfort for the
world in the terror the radio told.

Slim Riley was lying on an improvised cot when Thurston and the
representative of the Bureau of Standards joined him. Four walls of a
room still gave shelter in a half-wrecked building. There were candles
burning: the dark was unbearable.

"Sit down," said MacGregor quietly; "we must think...."

"Think!" Thurston's voice had an hysterical note. "I can't think! I
mustn't think! I'll go raving crazy...."

"Yes, think," said the scientist. "Had it occurred to you that that is
our only weapon left?

"We must think, we must analyze. Have these devils a vulnerable spot? Is
there any known means of attack? We do not know. We must learn. Here in
this room we have all the direct information th