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 their deadly fumes and pouring forth their sluggish, boiling lava. The scene about us now was lighted in a horrible blue‑green glare. A great cloud of thin smoke gathered, hung poised a moment, and then rolled slowly away—its deadly fumes hanging low to the ground and spreading ever wider as though eager to clutch the unsuspecting city in their deadly embrace.
The entire face of the cliff was now covered with the crawling blue fire, lapping avidly about with its ten‑foot tongues. We drew back, staring silently at each other's ghastly green faces.
"Let's—let's get away," Mercer whispered finally. "No use staying here now."
We hurried back to the nearest place where one of our projectors was set up. The two men guarding it looked at us anxiously, and smiled triumphantly when Miela told them what we had done. We stood beside them a moment, then Miela and I climbed to an eminence near by from which we had an unobstructed view of the city.
The light‑barrage still held steady. The individual, higher‑powered projectors as before swung their beams lazily about the country. We sat partly in the shelter of a huge bowlder, behind which we could have dropped quickly had one of them turned our way.
"Soon it will be there," Miela said softly, when we had been sitting quiet for a time.