The transmission they'd sent out was five minutes long. It began with a re-transmission of part of the message Earth had received. This plainly identified the signal from Earth as a response to the cryptic flutings. Then there were hummings. One dot, two dots, three, and so on. These hummings assured whoever or whatever was out yonder that the inhabitants of Earth could count. Then it was demonstrated that two dots plus two dots were known to equal four dots, and that four and four added up to eight. The inhabitants of Earth could add. There followed the doubtless interesting news that two and two and two and two was eight. Humanity could multiply. Arithmetic, in fact, filled up three minutes of the eight-hundred-kilowatt beam-signal. Then a hearty human voice--the president of a great university--said warmly: "_Greetings froth Earth! We hope for splendid things from this opening of communication with another race whose technical achievements fill us with admiration._" More flutings repeated that the Earth signal was intended for whoever or whatever used flutelike sounds for signaling purposes, and the message came to an end with an arch comment from the university president: "_We hope you'll answer!_" When this elaborate hodge-podge had been flung out to immensity, the prominent persons who'd devised it shook hands with each other. They were confident that if intelligent beings did exist where the mournful musical notes came from, interplanetary or interstellar communication could be said to have begun. The engineers who'd sweated together the equipment simply hoped their signal would reach its target. It did. It went out just after the end of a reception of a five-minute broadcast from M-387. Seventy-nine minutes should have passed before any other sound from M-387. But an answer came much more quickly than that. In thirty-four minutes, five and three-tenth seconds, a new signal came from beyond the sky. It came in a rush. It came from the transmitter out in orbit far beyond Mars. It came with the same volume. It started with an entirely new grouping of the piping tones. There was a specific crispness in their transmission, as if a different individual handled the transmitter-keys. The flutings went on for three minutes, then were replaced by entirely new sounds. These were sharp, distinct, crackling noises. A last sequence of the opening flutings, and the message ended abruptly. But silence did not follow. Instead, a steady, sonorous, rhythmic series of beeping noises began and kept on interminably. They were remarkably like the directional signals of an airway beacon. When the news broadcasts of the United States reported the matter, the beeping sounds were still coming in.