"Remember," O'Hara said, "I wrote that time telescopes in the Patrol? It was telescoping for me now--I was back again with old Hendrik Hudson, though thank God not in quite the same kind of boat. I was opening up the West again, seeing the amazing continent, the wonders that I'd seen before only as dotted lines and red-and-blue ink sworls on long-forgotten maps. And in five minutes--the five since I had passed the Curtain--I was exploring more of this tremendous northland than old Hendrik ever dreamed of." Wonders, yes--but wonders unfortunately very like those of the land mass of Siberia, and so no different from what he'd known before he smashed through the Curtain. O'Hara felt somehow as if the myths of the Lost Continent had let him down. Until he noticed the recording of his scintillometer. It had dropped only to .305 milliroentgens an hour. That was high--dangerously high according to the flying regulations of the Patrol, yet it had been much higher further north, toward the Curtain. He could only hope that with his progress south the count would gradually decline. Then it occurred to him that radioactive water might be running underneath the ice of the Mackenzie, draining southward from the Curtain, and he swerved hard toward the east, leaving the river bed some hundred miles behind before he made another reading. The milliroentgen count, rather than dropping, had risen to .325 an hour. And simultaneously O'Hara's memory dredged up a curious fact--the Mackenzie flowed toward the north. It could not possibly be contaminated from the Curtain. O'Hara now turned again toward the west, crossing the Mackenzie and heading for a tremendous region of ice-capped peaks, their vast flanks swathed with the silver sheen of the greatest glaciers he had ever seen--the northern reaches of the Rockies, he concluded, the neckbones of the spinal column of the continent. In this race westward, his milliroentgen count was sliding steadily, until, above the mountain chain itself, the count seemed stabilized at last at .285. Yet when he pushed beyond, toward the western coast--the Pacific--the count immediately began to jump again. He made the indicated correction in his flight, adhering to the southeast curvature of the mountain chain, and concluding that he had discovered a corridor of lesser contamination, its base upon the Curtain in the north, and its two flanks, on the eastern and western sides of the mountains, strongly radioactive.