When he reached the bridge with this all-important despatch, Jack found the captain in consultation with his officers. Tests of the temperature of the water were being made, and the skipper was listening attentively to the roaring of the siren.

If there was ice in the vicinity, the echo of the great whistle would be flung back and serve as a warning.

“Well, boy?” the captain turned impatiently on Jack.

“A message, sir. I think it’s important,” said the boy deferentially.

The captain glanced through it and whistled.

“Important! I should think it is. Just what I thought. Confound this ocean!”

He hastened over to his officers and showed them the despatch. A lively consultation followed, which Jack wished he could have overheard. He would have liked to know what further steps could be taken to avert the dangers amid which they were crawling forward.

As a matter of fact, all that could be done had been done. Humanly speaking, the Ajax was as safe as she could be rendered in the midst of the invisible dangers that, like white specters, might be swarming about her even now.

Jack was ordered back to the wireless room and told to stand by for any further information. The captain evidently placed great reliance on getting further word of the location of the ice-fields and bergs.

But, although Jack worked ceaselessly, sending out his crackling, sparkling calls, no reply came back out of the blinding fog. Clearly the ship that had sent the wireless that was so all-important had passed out of his zone, or else the “atmospherics” were arrayed against communication.

It was a thrilling and not altogether a comfortable thought to consider that at any moment there might loom above them, out of the choking mist, a mountainous white form that might well spell annihilation for the sturdy tanker.

Raynor, whose hand was now quite well, poked his head in at the door. He was grimy and soot-covered but cheerful, and was going off watch.

“Hello, Jack,” he cried, “what do you think of this? Burning soft coal in heaven, I guess! Isn’t it a smother, for fair?”

“It sure is,” rejoined Jack, “but the fog isn’t the worst of it.”

Raynor looked surprised.

“What are you driving at? They’ve had us on double watches since it started, stopping and starting up the engines till they must think they’re being run by a gang of crazy engineers.”

“It’s icebergs, old fellow,” said Jack in an awed tone.

“Icebergs! At this time of year, that’s unusual,” said Raynor.

“I don’t know about that, but I got a message from the Westerland telling about them.”

“The dickens, you say! No wonder the old man is worried out of his socks. Say, Jack,” went on the young engineer.

“Well?”

“What a fine chance we’d stand down below there, if we ever hit anything, eh?”

And young Raynor, whistling cheerily, passed on to his room to wash up and change.

Jack gave a shudder. “If they hit anything.” Well did he know what a small chance the men in the grimy, sooty regions of the fire-room and engine-space would stand in such a contingency. It would be their duty to keep up the fires till the rising water put them out, and then—every man for himself!

Woo-oo-oo-oo-oo-oo! boomed the siren.

“Ugh! You sound as cheerful as a funeral,” shuddered Jack; and, to divert his mind into a more cheerful channel, he fell to running the wireless scale, in the hope that he might find himself in tune with some other ship with fresh news of the white monsters of the northern polar cap.

But the white silences were broken by no winged messages; and so the afternoon waned to twilight, and night descended once more about the fog-bound ship.

The strain of it all began to tell on the young wireless man. He made hourly reports to the shrouded figures on the bridge that looked like exaggerated ghosts in the smother of fog. The lights on the ship shone through the obscurity like big, dim eyes, and the constant booming and shrieking of the siren grew nerve-racking.

Vigilance was the order of the night. Bridge, deck and engine-room were all alike keyed up to the highest pitch of watchfulness. At any moment a message of terror might come clanging from the bridge to the engineers’ region.

The suspense made Jack, strong-nerved as he was, feel like crying out. If only something would happen, he felt that he would not care so much, but this silent creeping through the ghostly fog was telling on him.

Half dozing at times, Jack sat nodding at his key. All at once, without the slightest warning what all hands had been waiting for with keyed-up nerves happened.

From somewhere dead ahead the shriek of the siren was hurled back through the fog in a volley of echoes.

It was Captain Braceworth himself who jumped to the engine-room telegraph and signaled:

“Full speed astern!”