Suddenly, like a flash of lightning, the true meaning of the scene going on below him dawned on the lad.

The tobacco smugglers! The men who worked with the gang of customs cheaters, with their headquarters across the dark river in New Jersey!

Yes; that was undoubtedly the explanation of it. What was he to do? Go below and alarm the engineer in charge of the fire-room crowd? No; the man was only an apprentice engineer, as young Ready knew, and more than probably he was in with the gang himself.

Back and forth moved the boat, dodging in and out of the black shadows cast by the dock. It was an ideal night for such work. The fog lay thick, like a blanket laid over river and city.

Through the curtain of mist boomed the hoarse voices of tugs and ferryboats as they played a marine game of blind man’s buff in the fog. Jack felt terribly alone. He might have summoned help from the dock, but the rising and falling noise of the riot, which was evidently still in progress, told him that the men in charge of the wharf already had their hands full.

All at once the boy had one of those swift flashes of inspiration that come sometimes like a bolt from the blue in moments of great emergency.

He would summon the police by wireless!

The police boats, as he knew, lay at Pier A, the Battery, with steam constantly up, so as to be able to dart off on the instant after wharf thieves and smugglers. They all carried wireless and he would be certain to catch an operator on duty. At any rate, there was a wireless attached to the marine police station itself, which was situated in a big building adjacent to the Aquarium.

With Jack to think was to act. He was swift, to spring to his key and begin sending out a call. He looked the code word up in his book and almost instantly the heavy spark began crackling and snapping out a summons:

Cracking like the lash of a giant whip, writhing like a tortured serpent of flame, the lithe, green spark leaped between its points. Never had Jack’s fingers worked so fast. Before he could summon the guardians of the harbor it might be too late. The boat might have gathered up its cargo of contraband and sneaked off like a thief in the night into the impenetrable fog.

At last, after an interminable wait, came an answer from out of space.

“This is H. P. What is it?”

“This is the tank steamer Ajax, lying at Pier 29, North River.”

“Yes, yes, yes.”

The answer came mapping back from amid a mystifying maze of other flying dots and dashes.

“There is a gang of tobacco smugglers at work here!”

“The dickens, you say! Hold on a minute.”

“All right. But you must hurry men up here if you want to nail them.”

“Who are you?”

“The wireless man of the Ajax. I was here late and saw the work going on.”

“Bully for you! We’ll rush Launch B up there on the jump.”

“Hurry! Hurry! Hurry!” chattered back Jack’s key; and then silence fell once more.

Jack jumped up from his sending table.

“At any rate, I’ve done my duty,” he thought.

He went to the door. He wanted to look down into the black fog-filled pit overside once more and see what was going on. Glancing cautiously over, he almost gave a gasp of delight.

A second boat was at work!

“My gracious, if they get here in time they’ll make a fine haul of doubtful fish!” he said to himself in a low voice.

The words were hardly out of his mouth when he felt a heavy hand on his shoulder. He was spun round like a top and found himself in the clasp of a giant fireman. The hairy-chested fellow was naked from the waist up, and his coal-smeared face and blood-shot eyes did not add to the beauty of his appearance.

Suddenly the man’s grip transferred itself to Jack’s neck. The fingers, hard as iron, closed on his windpipe. He felt his breath shut off and his eyes starting out of his head. The man threw him roughly to the deck, and as he did so Jack recognized in him the sailor who had hung back when the boat was to be launched to the rescue of the derelict, and whose place he had taken. The fellow had been transferred to the fire-room force as a punishment.

The boy could feel the giant’s hot breath fanning his face as the man knelt over him, one knee crushingly on his chest.

“So, my young gamecock, you bane play the spy, hey?” he snarled. “You bane forgat everything you seen, or overboard you go with your figurehead stove in!”