the man who Jack believed
struck down the diamond merchant and stole the stones might not get
suspicious at seeing them about in the corridors.

"I believe they must have changed their plans, after all," Jack was
thinking when, from the shore, there shot out, at tremendous speed, a
sharp-bowed, swift motor-boat. It headed straight for the _Columbia_. As
it drew closer, Jack saw it held two men. Both were blowing a whistle,
waving flags and pointing at the big ship as if they, like many other
small water craft, were just out to get a glimpse of the triumph of
American shipbuilders.

They maneuvered close alongside, while Jack's fingers grasped the rail
till the paint flaked off under the pressure he exerted in his
excitement. What was happening below? he wondered. Could Billy and his
companions carry out their part of the program? Not far from the boy the
diamond merchant, unconscious of the drama being enacted on his account,
stood, with bandaged head, explaining for the hundredth time the beauty
and the value of the gems he had lost.

"Five thousand thalers I give if I get them back," he declared.

Suddenly Jack's heart gave a bound. From a port far down on the side of
the ship, and almost directly under him, a white object was hurled. It
struck the water with a splash and spread out, floating buoyantly.

Instantly the black motor-boat darted forward, one of the men on board
holding a boat hook extended to grasp the floating life-preserver,
hidden in which was a king's fortune in gems.

Jack stood still just one instant. Then, driven by an impulse he could
not explain, he threw off his coat, kicked off the loose slippers he
wore when at work, and the next moment he had mounted the rail and made
a clean, swift dive for the life-preserver.

Billy rushed on deck, excitement written on his face, just as Jack dived
overboard.

"Jack! Jack!" he shouted.

But he was too late.

"Great Neptune, has the boy gone mad?" exclaimed Captain Turner, who had
passed along the deck just in time to see Jack's dive. Regardless of sea
etiquette, Billy grasped the skipper's arm and rushed into a narrative
of the plan he and Jack had hoped to carry out.

"But Dusenberry was too quick for us, sir," he concluded.

"Never mind that, now," cried the captain, "that boy may be in danger."

He looked over the rail, which, owing to most of the passengers being
busy below with their preparations for landing, was almost deserted.
Billy