As Arthur watched, this effect became more pronounced.  The tall Fifth Avenue Building across the way began to disintegrate.  In a moment, it seemed, there was only a skeleton there.  Then that vanished, story by story.  A great cavity in the earth appeared, and then another building became visible, a smaller, brown-stone, unimpressive structure.

With bulging eyes Arthur stared across the city.  Except for the flickering, he could see almost clearly now.

He no longer saw the sun rise and set.  There was merely a streak of unpleasantly brilliant light across the sky.  Bit by bit, building by building, the city began to disintegrate and become replaced by smaller, dingier buildings.  In a little while those began to disappear and leave gaps where they vanished.

Arthur strained his eyes and looked far down-town.  He saw a forest of masts and spars along the waterfront for a moment and when he turned his eyes again to the scenery near him it was almost barren of houses, and what few showed were mean, small residences, apparently set in the midst of farms and plantations.

Estelle was sobbing.

“Oh, Mr. Chamberlain,” she cried.  “What is the matter?  What has happened?”

Arthur had lost his fear of what their fate would be in his absorbing interest in what he saw.  He was staring out of the window, wide-eyed, lost in the sight before him.  At Estelle’s cry, however, he reluctantly left the window and patted her shoulder awkwardly.

“I don’t know how to explain it,” he said uncomfortably, “but it’s obvious that my first surmise was all wrong.  The speed of the earth’s rotation can’t have been increased, because if it had to the extent we see, we’d have been thrown off into space long ago.  But—­have you read anything about the Fourth Dimension?”

Estelle shook her head hopelessly.

“Well, then, have you ever read anything by Wells?  The ’Time Machine,’ for instance?”

Again she shook her head.

“I don’t know how I’m going to say it so you’ll understand, but time is just as much a dimension as length and breadth.  From what I can judge, I’d say there has been an earthquake, and the ground has settled a little with our building on it, only instead of settling down toward the center of the earth, or side-wise, it’s settled in this fourth dimension.”

“But what does that mean?” asked Estelle uncomprehendingly.

“If the earth had settled down, we’d have been lower.  If it had settled to one side, we’d have been moved one way or another, but as it’s settled back in the Fourth Dimension, we’re going back in time.”

“Then—­”

“We’re in a runaway skyscraper, bound for some time back before the discovery of America!”

III.

It was very still in the office.  Except for the flickering outside everything seemed very much as usual.  The electric light burned steadily, but Estelle was sobbing with fright and Arthur was trying vainly to console her.