"Now what?" asked Christine. "I'm going to call Don," said Walt. "Iffen and providen we can find a live jack." He took a handset from his kit of tools and plugged it into the jack below the thermostat. He jiggled a tiny switch and pressed a little red button, and after a full three minutes, he said "Damn," under his breath and dropped the handset back into his tool kit. "Nobody's paying much attention to the telephone from this section of Venus Equilateral any more," he said. "There's a live one in the cold room, though. Let's take a look around first." "Which way?" Walt thought for a moment. "We set the cold room about one-third of the way from the North End because it was as far from the rest of the station's operating and living section as possible while commensurable with being reasonably close to the labs," he said. "We're not very far--perhaps a hundred yards from the axis. We're about a mile from the North End. "Now, if I were Kingman, I'd set up shop in some place as far from the operating section as possible commensurable with an out of the way place--and definitely far from the laboratories. Then I'd select a place as far from me as I could get without too much danger of having the effect detected." Christine nodded. "If Venus Equilateral were a cube, you'd take one corner and chill off the opposite corner." "Venus Equilateral is a cylinder, and the skin is filled with people. However, you can set up an equation in differential calculus that will give you two spots as far from one another as possible with the least danger of detection from the ends or skin of a cylinder. The answer will give you two toroidal volumes located inside of the cylinder. You set your workshop in one and start the chill-off in the other--and right across the center from you." "And?" prompted Christine with a smile. "We used the same equation to locate the least dangerous place. Predicated on the theory that if the personnel need be protected from the danger area as much as the danger area need be concealed from people, we can assume the use of the same constants. Now, since by sheer coincidence Markus the Kingman selected a spot in the toroid that we also selected, it narrows our search considerably." "In other words, we chase down the length of the station, cross the axis, and knock on Kingman's door." "Right," said Walt. And being firmly convinced that mixing pleasure with business often makes the business less objectionable, Walt kissed Christine once more before they started toward the place where they expected to find their troublemaker. * * * * * "About here," said Walt, looking up at a smooth bulkhead. "How are we going to find him?" asked Christine. The corridor was long and die-straight, but both walls were sheer for thirty feet and unbroken.