And so he told himself now once more as well as Robur, the thing would be accomplished. In the light of that ruddy illumination he would descend to demand a parley with Helmor in person. It was so he would regain his wife and son--that Naia of Aphur--and Jason, Son of Jason, would be rewon. The fire of his determination, of his completed plan, blazed back at Robur with the light of a mighty purpose--a thing conceived in weary weeks of ceaseless thought and labor--a thing not to be any longer changed or swerved from its course. Before that light Aphur's governor paled slightly and set his lips. "Aye," he said a trifle gruffly because of his blended emotions, "now I understand thee, Jason. But it would take Zitu's Mouthpiece to undertake it in such fashion. And what does Robur of Aphur to aid the success of the venture?" Once more Croft smiled. He laid a hand on his companion's shoulder. "He watches from the sky for any message I shall flash with the signal-lamp I shall carry--which, being interpreted to him by the man of the message tower, he shall see translated instantly into deeds. So shall he safeguard Jason's life--perhaps." "Perhaps, aye," said Robur. "So be it. I shall send the message as Zitu's Mouthpiece directs. As for the rest, I like it not." Turning, he stalked from the room with a gloomy face. To himself, Croft admitted perforce that his plan was in the nature of a somewhat desperate chance. Yet he believed that he had read the Zollarian spirit aright--felt assured that he was predicting Helmor's actions correctly, when the final issue should be his to face, that he had erected his counter move on a firm foundation of human nature--was counting not overmuch on the mental attitude to be induced by the menace of a fiery dissolution rained down upon defenseless heads out of space. Returning with the assurance that he had despatched a messenger with his orders, Robur found him no whit less firm in his resolution, and they discussed all details attendant on the departure of the blimps through the further course of the night. * * * * * Morning ushered in three days of well-nigh ceaseless toil, of practise with the giant aircraft by day--of an overhauling of them, a correcting of minor faults by night, of consultations with the fliers in which every step of the expedition was explained to them by Croft--of a grooming and testing of the six planes that were to accompany the monster dirigibles north. Mutlos of Cathur sent back word the first day that the galley for Niera had put forth. That same night Croft and Robur visited the wireless tower, and Croft demonstrated his signaling-flash. The man, trained to receiving and sending, read the code with little trouble, transcribing more than one message correctly and then flashing them back to Croft. Then, seating himself again at his key, he sent word to Zitra that the expedition was about to set forth.