"I must apologize, lieutenant, for dropping in on you so unceremoniously." He stopped, wondering if the man with the white beard understood a word of what he was saying. "The natural way to come in, when you travel in the air," the old man replied. "At least, you came in openly. I can promise you a better reception than you got at that city to the west of us a couple of days ago." "Now how did you know we'd had trouble at Cincinnati day-before-yesterday?" Loudons demanded. The old man's eyes sparkled with childlike pleasure. "That surprises you, my dear sir? In a moment, I daresay you'll be amazed at the simplicity of it. You have a nasty rip in the left leg of your trousers, and the cloth around it is stained with blood. Through the rip, I perceive a bandage. Obviously, you have suffered a recent wound. I further observe that the side of your flying machine bears recent scratches, as though from the spears or throwing-hatchets of the Scowrers. Evidently they attacked you as you were leaving it; it is fortunate that these cannibal devils are too stupid and too anxious for human flesh to exercise patience." "Well, that explains how you knew we'd been recently attacked," Loudons told him. "But how did you guess that it had been to the west of here, in a ruined city?" "I never guess," the oldster with the silver bar and the keystone-shaped red patch on his left shoulder replied. "It is a shocking habit--destructive to the logical faculty. What seems strange to you is only so because you do not follow my train of thought. For example, the wheels and their framework under your flying machine are splashed with mud which seems to be predominantly brick-dust, mixed with plaster. Obviously, you landed recently in a dead city, either during or after a rain. There was a rain here yesterday evening, the wind being from the west. Obviously, you followed behind the rain as it came up the river. And now that I look at your boots, I see traces of the same sort of mud, around the soles and in front of the heels. But this is heartless of us, keeping you standing here on a wounded leg, sir. Come in, and let our medic look at it." "Well, thank you, lieutenant," Loudons replied. "But don't bother your medic; I've attended to the wound myself, and it wasn't serious to begin with." "You are a doctor?" the white-bearded man asked. "Of sorts. A sort of general scientist. My name is Loudons. My friend, Mr. Altamont, here, is a scientist, also."