But though it swayed and quivered, as in the grasp of an earthquake, it held.

Stern circled Beatrice with his arm.

"Courage, now! Steady now, _steady!_" cried he.

The grinding, the booming of down-hurled stones and walls died away; the echoes ceased. A wind-whipped cloud of steam and smoke burst up, fanlike, beyond the edge of the roof. It bellied away, dim in the night, upon the stiff northerly breeze.

"Fire?" ventured the girl.

"No! Nothing to burn. But come, come; let's get out o' this anyhow.

There's nothing doing, any more. All through! Too much risk staying up here, now."

Silent and dejected, they made their cautious way over the shaken roof. They walked with the greatest circ.u.mspection, to avoid falling through some new hole or freshly opened creva.s.se.

To Stern, especially, this accident was bitter. After nearly a fortnight's exhausting toil, the miserable fiasco was maddening.

"Look!" suddenly exclaimed the engineer, pointing. A vast, gaping canyon of blackness opened at their very feet--a yawning gash forty feet long and ten or twelve broad, with roughly jagged edges, leading down into unfathomed depths below.

Stern gazed at it, puzzled, a moment, then peered up into the darkness above.

"H-m!" said he. "One of the half-ton hands of the big clock up there has just taken a drop, that's all. One drop too much, I call it. Now if we--or our rooms--had just happened to be underneath? Some excitement, eh?"

They circled the opening and approached the tower wall. Stern picked up the rough ladder, which had been shaken down from its place, and once more set it to the window through which they were to enter.

But even as Beatrice put her foot on the first rung, she started with a cry. Stern felt the grip of her trembling hand on his arm.

"What is it?" exclaimed he.

"Look! _Look!_"

Immobile with astonishment and fear, she stood pointing out and away, to westward, toward the Hudson.

Stern's eyes followed her hand.

He tried to cry out, but only stammered some broken, unintelligible thing.

There, very far away and very small, yet clearly visible in swarms upon the inky-black expanse of waters, a hundred, a thousand little points of light were moving.

CHAPTER XV

PORTENTS OF WAR

Stern and Beatrice stood there a few seconds at the foot of the ladder, speechless, utterly at a loss for any words to voice the turmoil of confused thoughts awakened by this inexplicable apparition.

But all at once the girl, with a wordless cry, sank on her knees beside the vast looming bulk of the tower. She covered her face with both hands, and through her fingers the tears of joy began to flow.

"Saved--oh, we're saved!" cried she. "There _are_ people--and they're coming for us!"

Stern glanced down at her, an inscrutable expression on his face, which had grown hard and set and ugly. His lips moved, as though he were saying something to himself; but no sound escaped them.

Then, quite suddenly, he laughed a mirthless laugh. To him vividly flashed back the memory of the flint spear-head and the gnawed leg-bone, cracked open so the marrow could be sucked out, all gashed with savage tooth-marks.

A certain creepy sensation began to develop along his spine. He felt a p.r.i.c.kling on the nape of his neck, as the hair stirred there.

Instinctively he reached for his revolver.

"So, then," he sneered at himself, "we're up against it, after all?

And all my calculations about the world being swept clear, were so much punk? Well, well, this _is_ interesting! Oh, I see it coming, all right--good and plenty--and soon!"

But the girl interrupted his ugly thoughts as he stood there straining his eyes out into the dark.

"How splendid! How glorious!" cried she. "Only to think that we're going to see people again! Can you imagine it?"

"Hardly."

"Why, what's the matter? You--speak as though you weren't--_saved!_"

"I didn't mean to. It's--just surprise, I guess."

"Come! Let's signal them with a fire from the tower top. _I'll_ help carry wood. Let's hurry down and run and meet them!"

Highly excited, the girl had got to her feet again, and now, clutched the engineer's arm in burning eagerness.

"Let's go! Go--at once! This minute!"

But he restrained her.

"You don't really think that would be quite prudent, do you?" asked he. "Not just yet?"

"Why not?"

"Why, can't you see? We--that is, there is no way to tell--"

"But they're coming to save us, can't you see? Somehow, somewhere, they must have caught that signal! And shall we wait, and perhaps let them lose us, after all?"

"Certainly not. But first we--why, we ought to make quite sure, you understand. Sure that they--they're really civilized, you know."

"But they _must_ be, to have read the wireless!"

"Oh, you're counting on that, are you? Well, that's a big a.s.sumption.

It won't do. No, we've got to go slow in this game. Got to wait. Wait, and see. Easy does it!"

He tried to speak boldly and with nonchalance, but the girl's keen ear detected at least a little of the emotion that was troubling him. She kept a moment's silence, while the quivering lights drew on and on, steadily, slowly, like a host of fireflies on the bosom of the night.

"Why don't you get the telescope, and see?" she asked, at length.