"Millions. Every day, some physicist comes up with a new idea on sub-nucleonics. Within a week or so, enough of these ideas have snowballed to produce a slight modification that will improve a spacedrive--increase its speed, improve its efficiency, and so on. Within six or eight months, enough improvements have built up to make it worthwhile to incorporate them into the drive we're building. If North American used production line robots, we'd have to rip out the whole bunch and rebuild 'em to make the new generator. Why? Because the ordinary robotic device is a specialist; it can, at most, do two or three things--usually only one. And if you eliminate the thing that a particular robot does, or change it a little, you have to rebuild the tools and re-arrange them before reprogramming the whole line. "The waldo, a working replica of the human arm and hand, isn't specialized like that; it's adaptable; it can do anything. If we have to modify the design, all we have to do is reprogram the tapes, which is a comparatively easy job. "And besides, if anything goes wrong down there, we can put the hands on manual and go trouble-shooting, something we couldn't do with production line stuff." "I see," the major said, nodding. "Ingenious." He glanced at his wrist. "Do you suppose Mr. Klythe is through yet?" The smile that touched Crayley's mind did not reach his face. "I think he's just about through." His voice was completely innocent of any subtle innuendoes. * * * * * He glanced again at the screen that pictured the hundreds of hands moving automatically through their intricate motions in the production tunnel deep underground, then touched a switch. As the screen faded to blankness, he turned and led the way down the corridor to Klythe's office. Crayley paced his steps neatly so that he would stay just a foot in the lead. A foot, no more. Too much would be obvious. A foot was quite enough to show who was leading. His lean face was, as always, set in a placid mask. A thousand years before, Lewis Crayley might have worn a helmet of steel to hide his thoughts. Two hundred years before, he might have worn eyeglasses. Now, since there was no excuse to wear either, Crayley could only hide behind his own face. It was a face well constructed for the purpose. The nose was large and prominent--plenty of room to hide behind a nose like that. The brows were craggy and shaggy, overshadowing the half-closed eyes beneath them. The heavy mustache, which he wore in spite of the fact that it was looked upon as an anachronism, effectively concealed any expression the thin, firm mouth might show. His hands, too, were useful. Their quick, nervous movements distracted attention from the face when they were away from it, and effectively concealed it when they were nervously rubbing his nose or stroking his mustache.