An hour before--under direction of Croft and Robur--it had been dragged slowly forth from its concealing shed. With filled tanks its engines waited the awakening touch of the engineers--men selected for this first attempt at dirigible navigation from the aviation personnel by Croft himself. A huge flash of the liquid fire, equipped with its spraying device, was attached to the carrier designed to hold it. When this was done Croft and Robur stepped aboard. A hundred workmen--men who had labored to construct it--held the ropes that still controlled it, ready to release it at a word. "Let go!" That word came in the Mouthpiece of Zitu's voice. Two hundred hands relaxed their hold upon the ropes. The blimp soared toward the skies. Himyra fell away beneath it, became a red gem on the yellow sand of the desert, the breast of Aphur, pierced by the thread of the Na like a sparkling, supporting chain. To the north and east the waters of the Central Sea showed as bright as burnished silver under the first rays of the sun. Robur made no comment, said no word. He stood tight-lipped, gripping the rail of the platform on which they rode with tensely muscled hands. Croft ordered the engines started--and even so there was no feeling that the mighty fabric moved. Rather it seemed stationary, the only solid thing in all existence, while Palos and all it held dropped away from beneath it, until Himyra's palaces and shops and houses became things no larger than the toys of children, her people, pigmies moving antlike on her streets. Croft pointed beyond the walls. "The desert," he said and watched while the blimp answered to the manipulation of her engines--her rudder and vanes. Then and then only he spoke to Robur for the first time. "The desert. Recall you, Rob, the morn of the first motur in Himyra, when we drove into it from Himyra's walls, and Lakkon's gnuppas bolted, and I touched the hand of Naia of Aphur first?" "Aye." Robur turned. Himyra was receding as the blimp followed her new course. "By--Zitu--we are aiming for it again." Croft nodded. "It is in my mind to try first the liquid fire upon its scanty vegetation, where it can do small harm." And after that he waited until they flew above a comparatively level tract of country, covered by a low-growing shrub, that throve on scanty moisture, before he stationed himself at the spraying device and opened the valve of the flask. Far below, the scrub blossomed suddenly into tiny points of color like swiftly opening flowers--that grew, expanded, ran together in patches and lines of quivering light, until the whole mass of vegetation vanished, blotted out beneath a leaping sea of flame. A moment before it had lain there unchanged, as it and the desert had lain practically unchanged for years, and now it was a seething, smoking, blazing thing, sinking down in a red destruction unloosed upon it from the skies.