The westward-bound Australian mail left its Hendon Airport at 5 P.M., Greenwich time, August 10. At 9 P.M., Washington time, in the luminous darkness of the late summer twilight, we saw its lights over Norfolk--the immense, quadruple banks of its lighted hull windows. It came down over the landing field where our little Dolphin, with three of us on board, was lying cradled and ready. It hovered; its electro-magnetic grapples caught us up; in ten minutes, with the great flyer on its westward way again, we were stored on its lower deck. Three of us on board: Dr. Plantet, Polly, and myself. We had had no heart to try and find a last minute substitute for Arturo. We could handle the Dolphin, we two men. It was, indeed, a craft with every modern device operated by the levers in its forward instrument room, of one-man control. We had found no trace of Arturo. Dr. Plantet had uttered one anxious, heartfelt cry: “Why did he not tell me? I would have understood and advised him.” Ah, but there lay the trouble! He would have advised his son; but he could not, probably, have understood! Whatever Arturo contemplated, quite evidently he feared that his father would have disapproved of it. And, disapproving, would have forbidden him to do it, with a gruff command enforced against all possibility of argument. Arturo knew it; Polly and I, as we read his timorous, pleading little note, realized it was true. But Dr. Plantet did not think of that, and there was no one to tell him, and no use in telling him. He had done what he could to trace Arturo. The lad’s own small Wasp was gone from its hangar. Arturo had gone alone, by air. For an hour that afternoon when we returned from Norfolk to find him gone, Dr. Plantet shut himself up with his instruments; notified the authorities; had every detective bureau at every transfer point and in all the traffic towers of the country on the watch. But Arturo had evidently planned carefully. No report of him came to us. We were very busy those last hours. With all his worry over his son--shot through with anger also, I am sure--Dr. Plantet would not let it interfere with our voyage. That was not his way; though he was right in that, of course. We were not going on a mere experimental voyage to try and chart the great unknown deeps. That was a mere incidental. The oceans were still receding; the deeps might soon be dry, so that any one could see and explore them. By this August 10, another eight fathoms were gone from the oceans. Some eighteen fathoms in all--over a hundred feet. We heard a newscaster give the figures on the evening of August 9. The oceans down nearly a hundred feet below low tide levels, everywhere, and the world was seething with the confusion of it.