Finally he puts on his artilleryman’s ear protectors and lets the Digital Computer howl through the calculation. The room gets much hotter. A vacuum tube burns out, and then another one. Waterhouse replaces them. That’s easy because Lieutenant Colonel Comstock has made a basically infinite supply of tubes available to him—quite a remarkable feat during wartime. The filaments of all those massed tubes glow redly and shine palpable radiant heat across the room. The smell of hot oil rises from the louvers on the ETC card machines. The stack of blank cards in the input hopper shortens mysteriously as they vanish into the machine. Cards skitter into the output bin. Waterhouse pulls them out and looks at them. His heart is pounding very hard.