were to set fire to it in several places with our small
light-ray torches we could be assured of its burning steadily. And its
fumes, without warning, blowing directly over the city--I shuddered as the
whole thing became clear to me.

"Good God, man--"

"That'll smoke 'em out," declared Mercer, waving his hand again toward the
cliff. "I ask you now, won't that smoke 'em out?"

"Tao's men--yes." Miela's face was grave as she answered Mercer's
triumphant question. "It will do that, Ollie. Kill them all, of a
certainty; but that whole city there--"

Mercer stared at his feet, toying idly with the little torch in his hand.

"Can you think of any other way to get at Tao?" he asked.

Anina met my eyes steadily.

"There is no other way," she said quietly. "It must be done. It is your
world--your people--we must think of now. And you know there is no other
way."

We decided at last to try it. Once we had made the decision, we proceeded
as quickly as possible to put the plan into execution. We moved our
encampment farther away, well out of danger from the fumes.

We mounted several of the projectors in positions where their rays could
reach the surrounding country, and the sky, although not the city itself.
Then, ordering our men and girls to hold themselves in readiness for
whatever might occur, we four went off together to fire the sulphur.

The wind was blowing directly toward the city as we stood at the base of
the cliff, a silent little group. I think that now, at this moment, we all
of us hesitated in awe at what we were about to do.

Mercer broke the tension.

"Come on, Alan--let's start it off. Now is the time--a lot of places at
once."

We flashed on our little light-rays, and in a moment the sulphur was on
fire at a score of different points. We drew off a few hundred feet to one
side and sat down to watch it in the darkness. Overhead Tao's red beams
swept like giant search-lights across the inky sky.

The sulphur started burning with tiny little spots of wavering blue flame
that seemed, many of them, about to die away. Gradually they grew larger,
spreading out slowly and silently in ever-widening circles. Under the heat
of the flames the sulphur masses became molten, turned into a viscous dark
red fluid that boiled and bubbled heavily and dropped spluttering upon the
ground.

Slowly the blue-green flames spread about, joining each other and making
more rapid headway--a dozen tiny volcanoes vomiting