“Are there any settlements close by?” the captain asked. “Anybody who can come to our rescue?” “About twenty-five miles to the southwest, captain,” Mac answered. “Ben told me just where it was and advised me to land as close to it as possible. I thought this was as close as we dared approach, because the ground is treacherous between Hornfield and the settlement.” “What sort of settlement is it, Mac?” Isaac asked. “An oxygen-mining outfit in the Taurus Mountains. They’re mining for ore rich in oxygen to provide pressurized air for the underground terminal of Luna City, five hundred miles farther to the south. Ben said he thought they would have fliers that could get here in a short time as soon as they got our radio message.” “But we don’t have any radio,” Mr. Klecker said. “Yes we do, and we can thank the flier’s lifesaving equipment for that,” Captain Eaton said. He went to a cabinet built into the wall and pulled out an oblong box. On the top of it were the words: “SOS Automatic Transmitter.” “You mean that was in the flier all this time and that we could have used it earlier ourselves?” Garry asked in surprise. “Yes, you could have,” Captain Eaton replied. “I’m familiar with this transmitter,” the captain went on. “Let’s get the radio kit down.” When this was done, Captain Eaton donned one of the two space suits which the flier carried. When he was dressed, he entered the flier’s air lock, carrying the radio kit. Those inside the ship watched Captain Eaton walk about fifty feet from the flier and open the box containing the transmitter. “Gee, why does he have to open it up out there?” Patch wanted to know. “Couldn’t he transmit from inside the ship just as easy?” “No, not nearly as well,” Mac explained. “Just watch, and you’ll see why!” Captain Eaton took some things out of the box, and then, after tinkering with them for a few minutes, he set the transmitter in the pumice dust and ran back toward the flier as if he had just lighted a bomb fuse. A few seconds later the boys were surprised to see something resembling a giant snake spring from the ground beside the transmitter and extend straight up in the dark sky! “What in the world was that?” Patch asked in amazement. “That’s the antenna for the transmitter, isn’t it, Mac?” Garry asked. Mac nodded. “That long ropelike thing is hollow, and the antenna is in the middle of it. Captain Eaton released a switch that caused the casing to fill with compressed air, and that is what keeps it extended into the sky. That gives us a much better antenna than we could possibly have in here. Also, being as tall as it is, the radio waves leaving it can travel great distances and cross high places which they could not do if it were short. Understand?” The boys nodded.