MacReedy wandered over to stand beside him. He said, "I didn't _get_ it anywhere; it just seems like the logical next step in ordnance, General. I've had pretty good luck in the past, figuring things out this way. I had the Sherman tank plotted back in nineteen-forty--just before I was drafted. I hadn't dared trust my hunches till I saw my first one two years later at Pine Camp." "You were in the Army?" "Six years," said MacReedy. "Two years here in camp and Officer's Candidate School, then two abroad--Sicily, Anzio and the Rhone Valley. I stopped a piece of shell near Lyon, and put in the rest of my time in hospital." "Rough," said the General though he had neither the time nor the interest for sympathy. "Tell me how you 'figure' these things out. The Sherman tank, if you wish." MacReedy wagged his head modestly. "It wasn't too difficult, once I'd seen the General Grant. That one obviously wouldn't do; it was too high, needed a full-pivot turret. Yet the basic design was there--anyone who'd thought about it could have done the same. But it was a pleasant shock to learn I'd been right." "I see," said the General. "And you did the others by the same process--and you're always right?" "Not always," replied MacReedy. "I fluffed badly on the atomic cannon. I expected a longer barrel for greater muzzle-velocity and range; here, I'll show you." He led the way to a dusty wall shelf where imperfect and broken models crowded together. There was the A-cannon--not as it had appeared, but as the General knew it was going to look in two years, when certain needed changes were made. He said, "An understandable error. Unfortunately, mobility had to be considered." He paused, looked MacReedy straight in the eye. "I hope you didn't show any of this to your--previous visitor." MacReedy laughed. "Hardly," he replied. "I'm American, never fear. I'm just one of the lucky few who has been able to make a good living out of my hobby; I have no axes to grind." "We may have an axe to grind with you," said the General with a hint of grimness. The rocket-launcher and the improved A-gun were like the one-two punch of a good heavyweight-hitter. He went back to the XT-101, said, "About this twin-mount tank--how'd you figure we'd mount the automatic machinery outside the turret?" "That wasn't too difficult--if I'm right; and I gather I am," said MacReedy. "There's simply too much stuff to put inside a tank-turret; you've got to mount it outside. And that means plenty of protection, which means an extra armored sleeve. So...." 3 The General said, "MacReedy, why are you showing me this? I could be an imposter, a spy." "With that official limousine?" the model-maker countered. "I doubt it. Besides, Toby vouches for you." "Risky," said the General. "Besides," said MacReedy with the suggestion of a smile, "I've seen your picture in _Life_ magazine." He paused, added, "After all, in my humble way I'm a bit of an ordnance nut myself."