Terry suddenly felt a warm sympathy for Morton. It is bad enough to dispute with oneself when something incredible happens. But Dr. Morton had gone out on a limb. He'd been caught psychologically naked telling the truth, and now he was asked to explain it. And he couldn't. "This thing has got to come to a head!" he said angrily. "Sooner or later they'll find out that I don't calculate where it'll land by its behavior in space but by its landing spot! Davis, you've talked about stirring something up. For Heaven's sake, do it! You may save my reputation! And you...." "I'll try to think of something," said Davis reservedly. "I've got to have proof that my suspicions are right or wrong before I'm ruined. I know what you're planning to do. Do it! Is there anything that can be done here to help?" Davis spread out his hands helplessly. But Terry said, "Yes. Send a boat every so often to listen at the gap in the reef. Put an oar overboard and put your ear to the handle. You should hear the underwater hum, if it's still there. It was there this morning." Morton looked at him suspiciously. "Why check on it? Should it change?" "Perhaps," said Terry. "We've speared most of the deep-sea fish in the lagoon. Maybe we've interfered with ... the reports from the plastic objects, telling what was happening up here. There may be a reaction. If so, most likely the humming will stop, and after a longer or shorter time begin again. And then, if my guess is right, there'll be more deep-sea creatures in the lagoon." "Ha," said Morton. "I think you and I have the same kind of delusions! All right. I'll see that that's done. You two do the rest." He went abovedecks. When Terry got on deck, Dr. Morton's angular figure was already marching along the wharf to the shore. There was no ceremony of departure. The _Esperance_ cast off and her engine started. She moved toward the lagoon entrance under power only, but her sails were hoisted as she floated on, and Jug Bell was trimming the jib when she cleared the opening to the sea. The humming in the water was still audible to the submarine ear, close to the land. It occurred to Terry to take a bearing on the source of the sound, noting both the compass direction and the vertical angle from the reef. If his vertical-angle reading was accurate, a line from the reef to the source of the sound would touch the bottom at twenty-seven thousand feet down, between four and five miles away. The _Esperance_ sailed on. The humming duly faded away. Terry left the recorder picking up undersea sounds, without recording them. It relayed the underwater sounds to the people on deck. It was in Terry's mind to keep at least half an ear cocked to it, in case the mooing sounds, heard and recorded elsewhere, should come again.