The streets they were passing through now were strange. The falling darkness gave to everything an air of mystery. Here some great man-made dragon opened its mouth as if to swallow them, there a tattered sign fluttered and cracked in the wind. "The great Century of Progress!" Johnny whispered. "Here thousands swarmed along the Midway. Now all is still. Now-- "What was that?" He stopped dead in his tracks. Had he caught the sound of scurrying feet? Yes, he was sure of it. And there, well defined against a wall, were the shadows of two half crouching figures. One was tall, the other short. Johnny felt a chill run up his spine. Felix apparently had seen nothing, heard nothing. He had gone plodding stolidly on into the gathering darkness; was at this moment all but lost from sight. With a little cry of consternation, Johnny sprang after him. By the time he caught up to him they were at the spot where the balloon was kept. "We just release this clutch when we are ready to go up," Felix explained, "then up we go. There is a time arrangement that will set the electrically operated drum, winding us back down again in two hours. We only go up about three hundred feet. Cable holds us. Quite safe tonight, no wind to speak of." Johnny thought this a rather strange arrangement. "No guard here?" he asked. "No need. No one's allowed in the grounds unless they have a pass. Climb in. All set." Johnny did climb in, and up they went. Johnny had been in the air many times. For all that, he experienced a strange sense of insecurity as they rose a hundred, two hundred, three hundred feet into the murky air of night. "Pooh!" he exclaimed in a low breath. "It is nothing!" That he might throw off this feeling of dread, he busied himself with other thoughts. His gaze swept the city where lights were gleaming. "Where," he thought, "are Drew and Tom? Hunting pickpockets perhaps. And where is Captain Burns? I'm going to like him, I'm sure. He is so solid and real; but jovial for all that. He said he'd take me places. What places? I wonder. Dangerous places? He said--" His thoughts were broken in upon by Felix's voice: "Here we are at the top. Now for the test." The young inventor flashed on a powerful searchlight. "All I have to do is to connect this through a switch, aim my light at a window in our house, take up this microphone and say, 'Hello father!' He hears me and no one else in the world can. He-- "What!" he exclaimed in consternation. "The current is off. Someone cut the light cable!" "More than that!" Johnny's tone was sober. He was looking over the side of the balloon basket in which they rode. "The cable that holds us has been cut! We're drifting!" "You're right!" Consternation sounded in the older boy's voice. "We're going out into the night, over black waters. And there is no ballast!" "They got us, those two!" Johnny muttered. "What two?" Felix demanded.