low, but near the pitch of the transparent roof the glass was clear, and he found himself looking sheerly down upon it all. For awhile, in spite of the urgency of his guide, he gave way to vertigo and lay spread-eagled on the glass, sick and paralysed. Far below, mere stirring specks and dots, went the people of the unsleeping city in their perpetual daylight, and the moving platforms ran on their incessant journey. Messengers and men on unknown businesses shot along the drooping cables and the frail bridges were crowded with men. It was like peering into a gigantic glass hive, and it lay vertically below him with only a tough glass of unknown thickness to save him from a fall. The street showed warm and lit, and Graham was wet now to the skin with thawing snow, and his feet were numbed with cold. For a space he could not move. "Come on!" cried his guide, with terror in his voice. "Come on!"
Graham reached the pitch of the roof by an effort.
Over the ridge, following his guide's example, he turned about and slid backward down the opposite slope very swiftly, amid a little avalanche of snow. While he was sliding he thought of what would happen if some broken gap should come in his way. At the edge he stumbled to his feet ankle deep in slush, thanking heaven for an opaque footing again. His guide was already clambering up a metal screen to a level expanse.
Through the spare snowflakes above this loomed another line of vast windmills, and then suddenly the amorphous tumult of the rotating wheels was pierced with a deafening sound. It was a mechanical shrilling
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