"Aye," Croft assented. "Say also that Naia sends a greeting to her father, and that at present she lies safe from harm. Come, let us return to the palace since things are now arranged." Robur nodded. They entered his motur and drove back toward the red court, and the residential wing of the Aphurian government buildings, side by side, as they had on many another occasion when they labored together in Himyra's shops. And that night it was Croft made his promised visit to me to discover what I had learned concerning the thing on which more than anything else Naia's rescue appeared to depend. I was ready for him. I had not delayed in instituting my efforts at gaining the knowledge the use of which I had suggested, and I had been fortunate indeed. I had found the man I wanted almost at once--one who had served his country well in the chemical arm of the service, and was therefore qualified to give me the information of which I stood in need. My greatest difficulty had been in convincing him that I desired the knowledge for no improper use, but in the end I surmounted the task. And that night after Jason had roused me to his presence I recited the formula to him, and he cried out: "Zitu! Murray, the thing can be accomplished! Palos holds all that will be required." * * * * * Considering the stage of life on the other planet, that was a self-evident fact, but I knew he meant more than that. Before the Mazzerian war he had established a laboratory at Himyra in which he and Naia had gone more or less fully into chemical matters, and I felt he was fully assured concerning the things of which he spoke. "Good," I said, "then you can make it?" His thought waves beat back at me in a very passion of conviction. "Yes, and we'll carry it to them in something like your earth-born blimps--isn't that what you told me you called them when I was here in your institution as a patient?" "Blimps--dirigibles, you mean?" I questioned. "Yes," he said. "That's what I've been considering making, though I haven't told Rob about it yet. They'll be far more stable for the purpose than planes." "Why, yes," I agreed. "Croft, it's a rather peculiar thing, but before the armistice was signed in Europe each side was planning to blot out the major cities of the opposing nations beneath a fiery rain." For that was the thing I had proposed to Jason, and the secret for the production of the unquenchable liquid fire which could be stored and carried, and sprayed in a rain of death upon those against whom it was used, was the thing I had gained from Captain Gaylor, formerly connected with the department of gas and flame.