she asked quickly.

"Time enough to worry when it happens," Arthur retorted briefly.

"You--you aren't afraid we'll go back before the beginning of the
world, are you?" asked Estelle in sudden access of fright.

Arthur shook his head.

"Tell me," said Estelle more quietly, getting a grip on herself. "I
won't mind. But please tell me."

Arthur glanced at her. Her face was pale, but there was more
resolution in it than he had expected to find.

"I'll tell you, then," he said reluctantly. "We're going back a
little faster than we were, and the flaw seems to be a deeper one
than I thought. At the roughest kind of an estimate, we're all of
a thousand years before the discovery of America now, and I think
nearer three or four. And we're gaining speed all the time. So,
though I am as sure as I can be sure of anything that we'll stop
this cave-in eventually, I don't know where. It's like a crevasse
in the earth opened by an earthquake which may be only a few feet
deep, or it may be hundreds of yards, or even a mile or two. We
started off smoothly. We're going at a terrific rate. _What will
happen when we stop?_"

Estelle caught her breath.

"What?" she asked quietly.

"I don't know," said Arthur in an irritated tone, to cover his
apprehension. "How could I know?"

Estelle turned from him to the window again.

"Look!" she said, pointing.

The flickering had begun again. While they stared, hope springing
up once more in their hearts, it became more pronounced. Soon they
could distinctly see the difference between day and night.

They were slowing up! The white snow on the ground remained there
for an appreciable time, autumn lasted quite a while. They could
catch the flashes of the sun as it made its revolutions now,
instead of its seeming like a ribbon of fire. At last day lasted
all of fifteen or twenty minutes.

It grew longer and longer. Then half an hour, then an hour. The
sun wavered in midheaven and was still.

Far below them, the watchers in the tower of the skyscraper saw trees
swaying and bending in the wind. Though there was not a house or a
habitation to be seen and a dense forest covered all of Manhattan
Island, such of the world as they could see looked normal. Wherever
or rather in whatever epoch of time they were, they had arrived.

IV.

Arthur caught at Estelle's arm and the two made a dash for the
elevators. Fortunately one was standing still, the door open, on
their floor. The el