"Certainly," he replied, "because, although there is some sort of air, we don't know yet whether we shall be able to breathe it. It may be half carbon-dioxide for all we know; but a few matches will soon tell us that." Within a quarter of an hour they were again standing on the surface. Murgatroyd had orders to follow them as far as possible with the head searchlight, which, in the comparatively rarefied atmosphere, appeared to have a range of several miles. Redgrave struck a match, and held it up level with his head; it burnt with a clear, steady, yellow flame. "Where a match will burn a man should be able to breathe," he said. "I'm going to see what lunar air is like." "For Heaven's sake be careful, dear," came the reply in pleading tones across the wire. "All right; but don't open your helmet till I tell you." He then raised the hermetically closed slide of glass, which formed the front of the helmets, half an inch or so. Instantly he felt a sensation like the drawing of a red-hot iron across his skin. He snapped the visor down and clasped it in its place. For a moment or two he gasped for breath, and then he said rather faintly: "It's no good, it's too cold. It would freeze the blood of a salamander. I think we'd better go back and explore this place under cover. We can't do anything in the dark, and we can see just as well from the upper deck with the searchlights. Besides, as there's air and water here, there's no telling but there may be inhabitants of sorts such as we shouldn't care to meet." He took her hand, and to Murgatroyd's great relief they went back to the vessel. Redgrave then raised the _Astronef_ a couple of hundred feet and, by directing the repulsive force against the mountain walls, developed just sufficient energy to keep them moving at about twelve miles an hour. They began to cross the plain with their searchlights flashing out in all directions. They had scarcely gone a mile before the head-light fell upon a moving form half walking, half crawling among some stunted brown-leaved bushes by the side of a broad, stagnant stream. "Look!" said Zaidie, clasping his arm, "is that a gorilla, or--no, it _can't_ be a man."