across the sloping
transparency that covered this street of platforms, crawling on hands
and knees because of the slipperiness of the snowfall.

For the most part the glass was bedewed, and Graham saw only hazy
suggestions of the forms below, 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 of
extraordinary intensity that seemed to come simultaneously from every
point of the compass.

"They have missed us already!" cried Graham's guide in an accent of
terror, and suddenly, with a blinding flash, the night became day.

Above the driving snow, from the summits of the wind-wheels, appeared
vast masts carrying globes of livid light. They receded in illimitable
vistas in every direction. As far as his eye could penetrate the
snowfall they glared.

"Get on this," cried Graham's conductor, and thrust him forward to a
long grating of snowless metal that ran like a band between two slightly
sloping expanses of snow. I