"That's the top," he thought in that mind so light and so curiously not his own. He throttled the engine and went into a long spiral that was to end within a rod of where he had started on the brown sun-baked field. The last rays of the sun were slanting over distant mountains as he climbed stiffly from the machine. "Better than fifty thousand," exulted Colonel Boynton. "Of course your barograph will have to be calibrated and verified, but it looks like a record, Blake--and you had a full load. "Ready to go up and give merry hell to that other ship if she shows up?" he asked. But Captain Blake shook a dubious head. "Fifty thousand is just a start for that bird," he said. "You didn't see them shoot out of sight, Colonel. Lord knows when they quit _their_ climb--or where." "Well, we'll just have a squadron ready in any event," the colonel assured him. "We will make him show his stuff or take a beating--if that is what he wants." They were in the colonel's office. "You had better go and get warmed up," he told the flyer: "then come back here for instructions." But Blake was more anxious for information than for other comforts. "I'm all right," he said: "just tired a bit. Let me stretch out here, Colonel, and give me the dope on what you expect of our visitor and what we will do." * * * * * He settled back comfortably in a big chair. The office was warm, and Blake knew now he had been doing a day's work. "We will just take it as it comes," Colonel Boynton explained. "I can't for the life of me figure why the craft was spying around here. What are they looking for? We haven't any big secrets the whole world doesn't know. "Of course he may not return. But if he does I want you to go up and give him the once over. I can trust you to note every significant detail. "You saw no wings. If it is a dirigible, let's know something of their power and how they can throw themselves up into the air the way you described. Watch for anything that may serve to identify it and its probable place of manufacture--any peculiarity of marking or design or construction that may give us a lead. Then return and report." Blake nodded his understanding of what was wanted, but his mind was on further contingencies: he wanted definite instructions. "And," he asked; "if they attack--what then? Is their fire to be returned?" "If they make one single false move," said Colonel Boynton savagely, "give them everything you've got. And the 91st Squadron will be off the ground to support you at the first sign of trouble. We don't want to start anything, nor appear to do so. But, by the gods, Blake, this fellow means trouble eventually as sure as you're a flyer, and we won't wait for him to ask for it twice." * * * * *