"You're mistaken, Taylor," smiled Mercer. "That is not solid metal, you see. And it is an aluminum alloy that is not nearly as heavy as it looks. There are two walls, slightly over an inch apart, braced by innumerable trusses. The fabric is nearly as strong as that much solid metal, and infinitely lighter. They work all right, Taylor. I know, because I've tried them." "And this hump on the back?" I asked, walking around the odd, dangling figures, hanging like bloated metal skeletons from their chains. I had thought the bodies were perfect globes; I could see now that at the rear there was a humplike excrescence across the shoulders. "Air," explained Mercer. "There are two other tanks inside the globular body. That shape was adopted, by the way, because a globe can withstand more pressure than any other shape. And we may have to go where pressures are high." "And so," I said, "we don these things and stroll out into the Atlantic looking for the girl and her friends?" "Hardly. They're not quite the apparel for so long a stroll. You haven't seen all the marvels yet. Come along!" * * * * * He led the way through the patio, beside the pool in which our strange visitor from the depths had lived during her brief stay with us, and out into the open again. As we neared the sea, I became aware, for the first time, of a faint, muffled hammering sound, and I glanced at Mercer inquiringly. "Just a second," he smiled. "Then--there she is, Taylor!" I stood still and stared. In a little cove, cradled in a cunning, spidery structure of wood, a submarine rested upon the ways. "Good Lord!" I exclaimed. "You're going into this right, Mercer!" "Yes. Because I think it's immensely worth while. But come along and let me show you the _Santa Maria_--named after the flagship of Columbus' little fleet. Come on!" Two men with army automatics strapped significantly to their belts nodded courteously as we came up. They were the only men in sight, but from the hammering going on inside there must have been quite a sizeable crew busy in the interior. A couple of raw pine shacks, some little distance away, provided quarters for, I judged, twenty or thirty men. "Had her shipped down in pieces," explained Mercer. "The boat that brought it lay to off shore and we lightered the parts ashore. A tremendous job. But she'll be ready for the water in a week; ten days at the latest." "You're a wonder," I said, and I meant it. * * * * * Mercer patted the red-leaded side of the submarine affectionately. "Later," he said, "I'll take you inside, but they're busy as the devil in there, and the sound of the hammers fairly makes your head ring. You'll see it all later, anyway--if you feel you'd like to share the adventure with me?"