"Pressure, thirty pounds per square inch. Surface gravity as compared to that of the Earth, two-fifths. Air-pressure about double that of the Earth, while a five-pound weight weighs only two pounds. A peculiar combination," reported Crane, and DuQuesne added: "Analysis about the same as our air except for two and three-tenths per cent of a gas that isn't poisonous and which has a peculiar, fragrant odor. I can't analyze it and think it probably an element unknown upon Earth, or at least very rare." "It would have to be rare if you don't know what it is," acknowledged Seaton, locking the Skylark in place and going over to smell the strange gas. Deciding that the air was satisfactory, the pressure inside the vessel was slowly raised to the value of that outside and two doors were opened, to allow the new atmosphere free circulation. Seaton shut off the power actuating the repeller and let the vessel settle slowly toward the ocean which was directly beneath them--an ocean of a deep, intense, wondrously beautiful blue, which the scientists studied with interest. Arrived at the surface, Seaton moistened a rod in a wave, and tasted it cautiously, then uttered a yell of joy--a yell broken off abruptly as he heard the sound of his own voice. Both girls started as the vibrations set up in the dense air smote upon their eardrums. Seaton moderated his voice and continued: "I forgot about the air-pressure. But hurrah for this ocean--it's ammoniacal copper sulphate solution! We can sure get all the copper we want, right here, but it would take weeks to evaporate the water and recover the metal. We can probably get it easier ashore. Let's go!" They started off just above the surface of the ocean toward the nearest continent, which they had observed from the air. CHAPTER XIII Nalboon of Mardonale As the Skylark approached the shore, its occupants heard a rapid succession of heavy detonations, apparently coming from the direction in which they were traveling. "Wonder what that racket is?" asked Seaton. "It sounds like big guns," said Crane, and DuQuesne nodded agreement. "Big guns is right. They're shooting high explosive shells, too, or I never heard any. Even allowing for the density of the air, that kind of noise isn't made by pop-guns." "Let's go see what's doing," and Seaton started to walk toward one of the windows with his free, swinging stride. Instantly he was a-sprawl, the effort necessary to carry his weight upon the Earth's surface lifting him into the air in a succession of ludicrous hops, but he soon recovered himself and walked normally. "I forgot this two-fifths gravity stuff," he laughed. "Walk as though we had only a notch of power on and it goes all right. It sure is funny to feel so light when we're so close to the ground." He closed the doors to keep out a part of the noise and advanced the speed lever a little, so that the vessel tilted sharply under the pull of the almost horizontal bar.