"This pulsemeter, Gus, what does it do? I haven't seen it before."
"You haven't?" the little man frowned. "Ah, no; you haven't. It's standard in most apperception centers, but not in yours. That's because in yours The Brain works under a permanent problem-load."
Lee shook his head. "I don't get it, Gus; you know I'm the village idiot of this mastermind community."
"It's like this," Gus explained. "The Brain has a given capacity. The Brain also has an optimal operation speed, a definite rhythm in which it works best. Now, if they feed The Brain too many problems too fast, it results in a shock load, the operations rhythm gets disturbed, efficiency goes down. On the other hand if The Brain works with an under-capacity problem load, that's just as bad. In that case the radioactive pyramidal cells will overheat and decompose. Consequently we must aim at a balanced and an even problems load. That's why these pulsemeters are built into all problem-intake panels for the operators to check upon their speeds.
"Take an average problem—rocket ballistics, let's say—parts of it may be as simple as adding two and two and others so bad Einstein would reach for the aspirin from out of his grave.
"Now I'll show you how it works; the main power is cut off but there's enough juice left in The Brain's system to make this pulsemeter react; it's even more sensitive than a Geiger-Mueller counter."
He surveyed a big switchboard and picked out an outlet marked "Pons Varolis for the plug-in." Then snapped a pair of earphones on Lee's head.
"There," he said "you'll both see and hear what it does in a little while."
A soft glow slowly spread over the slanting screen on top of the machine. A crackling as of static entered the earphones and turned into a low hum. On the left corner of the screen a faint green streak of luminosity crawled over to the right; its light gained in intensity and it began to weave and to dance. Simultaneously the hum became articulate like tickings of a heart only much faster.