When he finally found the door he leaned against it for some time, and then he gently eased it open. There was nothing but blackness on the other side, and at his first step he tripped and sprawled on a narrow flight of stairs, bruising a hip badly. He found his footing again. On quivering legs he climbed slowly and as silently as he could, clinging to the harsh, newly-sawed wood of the bannister. He could not seem to catch his breath. He had to gulp for air, and the darkness was shot through with red swirlings. He reached the top of the stairs, and another door. There was harsh gray light seeping around it, and he listened intently, allowing for the quick suck and thud of the pulse in his ears. When he heard nothing for a long time, he opened it. He was at the end of a long corridor lined with doors, and at the end there was another door opening on the street. Eager to get out of the building, and yet reluctant to leave as much as he knew of this world, he moved down the corridor with exaggerated caution. It was a shoddy building. The paint on the walls was cheap, and the linoleum on the floor was scuffed and warped. There were cracks in the plastering. Everything was rough--half finished, with paint slapped over it, everything drab. There were numbers on the doors, and dirty rope mats in front of them. It was an apartment house, then--but from the way the doors were jammed almost against each other, the apartments had to be no more than cubicles. Dreary, he thought. Dreary, dreary--who would live in such a place? Who would put up an apartment house for people of mediocre means in this neighborhood? But when he reached the street, he saw that it was humpy and cobblestoned, the cobbling badly patched, and that all the buildings were like this one--gray-faced, hulking, ugly. There was not a building he recognized--not a stick or stone of the _Himmlerstrasse_ with its fresh cement roadway and its sapling trees growing along the sidewalk. And yet he knew he must be on the exact spot where the _Himmlerstrasse_ had been--was--and he could not quite understand. He began to walk in the direction of _Unter Den Linden_. He was far from sure he could reach it on foot, in his condition, but he would pass through the most familiar parts of the city, and could perhaps get some inkling of what had happened. * * * * * He had suspected that the probability world his apparatus could most easily adjust him for would be one in which Germany had lost the war. That was a large, dramatic difference, and though he had refined his work as well as he could, any first model of any equipment was bound to be relatively insensitive. But as he walked along, he found himself chilled and repelled by what he saw.