In the lee of the Flying Road Racer the boys had arranged the wireless equipment, and were now occupied in securing the lower end of the antenna and adjusting the connecting wires from aerials to the instruments. At last all was ready, and the two canvas “balloons” were cut loose. Slowly but steadily they rose, carrying with them the strands of copper wire,—five of them, each one hundred feet in length. The wind had died down quite a lot, and there was not much strain on the wires as they were pulled skyward like the string of a kite. As the wires tightened and became extended to their full length the boys broke into a cheer. Held by the captive “balloons,” the five parallel wires made as effective an aerial as if they had been rigged to a lofty pole. “Boys,” exclaimed Professor Chadwick proudly, “that’s what I call a real wireless triumph!” “Wait and see if it works first, father,” said Jack, with a happy smile. He had not much doubt on this point, having solved the vexatious problem of getting his wires aloft. CHAPTER XXIV—AN APPEAL FOR HELP “What are you going to do now?” asked Tom of Jack, who, with the receivers clamped over his ears, was seated at the wireless apparatus. It was the middle of the afternoon, the storm had blown itself out and the sun was shining cheerfully. About the young inventors pressed the castaways,—for they had been awakened,—Captain Andrews, so that he might make an observation and get their exact position, and the rest to be on hand if need arose. Jack had just flashed out the location of the island, and with it a fervent appeal for help. From the balloon-supported wires above him, the message had gone shooting forth into space. But as yet no answer had come, though the lad sat with the transmitting switch open, waiting for a reply. “Maybe there are no ships in this part of the Gulf,” said Tom. “Well, with the power we have from that dynamo we ought to have gotten into communication with something before this,” said Jack impatiently. He turned his head toward the dynamo of the Flying Road Racer, which had been connected with the wireless apparatus and was whizzing away merrily. The motor, fed by a fresh supply of gas obtained by dumping in a new lot of crystals, of course supplied the motive power for the current maker. “Try again,” suggested Professor Chadwick. Jack threw over the switch to connect the transmitting appliances, and began manipulating the key once more. The message of distress crackled and flashed, like the snapping of a whip lash,—or, more truly, a thousand of them. Jack was utilizing every atom of power he could obtain. He calculated that he had at least one hundred and ten volts of current, which should be ample to send his messages for a great distance. After sending for a while he stopped and listened. But no message came beating against his ears, breathing a spirit of hope. “Try sending out a C. Q. D.,” said Abner Jennings.