Deirdre said something. Terry realized that she'd repeated it. He'd become absorbed in the possibilities of instrument-reporting from the surface to the depths and back again. "You're not listening," protested Deirdre. "I'm talking about the bathyscaphe that ought to be in Manila any day now." "I'm trying to picture myself going down in a bathyscaphe," said Terry hastily. "I don't think I'd like it." A bathyscaphe is a metal sphere with walls and windows of enormous thickness, hung from a metal balloon filled with gasoline for flotation. It is lowered to appalling depths with the help of heavy ballast, and is equipped with electric motors for independent motion. It carries powerful electric reflectors which allow as much as thirty or forty feet of visibility. It rises to the surface again when its ballast is dumped. There are only three such undersea exploring devices in the whole world. "I'm not at all sure you wouldn't like it," said Deirdre. Terry scowled at his own thoughts. There are opinions a man holds firmly without ever being aware of them, unless they are challenged, and if that happens, he is deeply suspicious of the challenge because it suggests that his opinion needs to be re-examined. Terry had been gathering scraps of information here, and unquestionable items there, resisting a conclusion all the while. It seemed fantastic to think that the plastic objects carried by deep-sea fish out of their natural environment were actually man-made instruments--telemetering apparatus closely comparable to the devices used to transmit information from outer space. It was wildly imaginative to suppose that they transmitted information from the water surface to the depths of the ocean; that fish had been driven up from the abyss in order to report what went on at the surface. Report to whom? It was the most fantastic of fantasies to think that there was curiosity, in the Luzon Deep, about the manners and customs of the inhabitants of the surface waters and of those areas not covered by the sea. But Terry stopped short. There were limits to the ideas he would allow his brain to think about. Deirdre walked away, and he assured himself he never thought of anything so ridiculous as the conclusions he had just reached. Presently, dinner was served, and Terry painstakingly acted like a perfectly rational person. After dinner Davis, as usual, settled himself down to enjoy a program of symphonic music from San Francisco, many thousands of miles away. And Deirdre vanished from sight again. Later on Terry found himself alone on the _Esperance's_ deck, except for Nick at the wheel--a mere dark figure seen only by the light of the binnacle lamp. There was a diffused, faint glow coming from the after-cabin hatch. Up forward, one of the crew-cuts plucked a guitar, and Terry could imagine Doug dourly trying to read poetry despite the noise. The sails were black against the sky. The deck was darker than the sea.