"Very pleased, Tenant, gentlemen. I met all of you young men last evening and I remember you," Altamont said. "Now, if you'll crowd in here, I'll explain what we're going to try to do." He showed them the old picture. "You see where the shadow of a tall building falls?" he asked. "We know the height and location of this building. Doctor Loudons will hold this helicopter at exactly the position of the top of the building and aim through the sights of the rifle, there. One of you will have this flag in his hand, and will move it back and forth. Doctor Loudons will tell us when the flag is in sight of the rifle." "He'll need a good pair of lungs to do that," Verner Hughes commented. "We'll use the radio. A portable set on the ground, and the helicopter's radio set," Altamont said. To his surprise, he was met with looks of incomprehension. He had not supposed that these people would have lost all memory of radio communication. "Why, that's wonderful!" the Reader exclaimed, when the explanation was concluded. "You can talk directly. How much better than just sending a telegram!" "But, finding the crypt by the shadow, that's exactly like the--" Murray Hughes began, then stopped short. Immediately, he began talking about the rifle that was to be used as a surveying transit, comparing it with the ones in the big first-floor room at the Aitch-Cue House. Locating the point where the shadow of the old Cathedral of Learning had fallen proved easier than either Altamont or Loudons had expected. The towering building was now a tumbled mass of slagged rubble, but it was quite possible to determine its original center, and with the old data from the excellent reference library at Fort Ridgeway, its height above sea level was known. After a little jockeying, the helicopter came to a hovering stop, and the slanting barrel of the rifle in the vise pointed downward along the line of the shadow that had been cast on that afternoon in June, 1993. The cross-hairs of the scope sight centered almost exactly on the spot Altamont had estimated on the map. Guiding himself by peering through the rifle-sight, Loudons brought the helicopter slanting down to land on the sheet of fused glass that had once been a grassy campus. "Well, this is probably it," Altamont said. "We didn't have to bother fussing around with that flag after all. That hump over there looks as though it had been a small building, and there's nothing corresponding to it on the city map. That may be the bunker over the stair-head to the crypt." They began unloading equipment--a small, portable nuclear-electric conversion unit, a powerful solenoid-hammer, crowbars and intrenching tools, tins of blasting plastic. They took out the two hunting rifles and the auto-carbines, and Altamont showed the young men of Murray Hughes' detail how to use them.