again. Big, exciting, and dangerous! Well, that was the life. Life, action, thrills—and a touch of romance! Boy-oh-boy! That was the stuff!

But there was a gleam of light on the water! There could be no mistaking it. It was closer, too. What should he do? Call someone? After a moment’s thought he decided to wait. His flashlight would reach out a hundred feet or more. Time enough when those people, whoever they were, came within reach of his light. So, somewhat excited, Johnny waited by the gunwale, watching the bobbing of a tiny light—now here—now there—now gone—but ever coming nearer.

He waited, breathless, tense, expectant, watching for some craft. What would he see? Dark faces? Gleaming spears? Flashing machetes? Soon he would know.

When at last he cast the gleam of his powerful light on the spot where that golden glow had last shown, he gasped in astonishment.

“A girl!” he exclaimed, amazedly.

Yes, it was a girl. In a dugout patterned after a white man’s canoe, she came straight on, without a sound. Her boy’s shirt and blue slacks were faded, but clean. Her reddish-golden hair fairly gleamed in the light. She had a round, freckled face and smiling eyes.

As she came alongside, Johnny reached over, took her line and made it fast. Then he gripped her small, firm hand and helped her over the low rail.

“I—I had to come,” she breathed. “I—I’ve been watching you for days. What—” there was tense eagerness in her voice, “what is that big ball you let down into the sea?”

“That,” said Johnny, after bringing her a deck chair, “is for going down, down, down, to the bottom of the sea!”

“I—I hoped it would be.”

“Why”

“Our trading schooner, the Swallow, sank. We—we can’t find it. I thought—”

“Thought these people might find it for you?”

“Yes! Yes—that’s it! Do you suppose—”

“I can’t tell about that. You see,” Johnny hesitated, “I’m only a watch, on this boat. I—well you might say I’m just a tropical tramp!”

“That,” said the girl, putting out her hand, “makes us kin! Grandfather and I are beach-combers!

“You see,” she went on, after giving Johnny’s hand a quick grip, “I sort of ran away from home. No, not quite that. I was half through college. It cost an awful lot. My folks couldn’t afford it, but they wanted me to finish anyway. I wouldn’t let them spend the money, so I asked grandfather to send me a steamship ticket. He did—and here I am! It’s grand! Really gorgeous! These nights.” She spread her arms wide. “The jungle! The water rushing along the shore, the birds, the flowers, romance, adventure, everything! It’s just grand!” Her face fairly shone.

“But our boat,” her voice dropped, “sprang a leak in a storm. The natives were sailing her. They lost the location and we can’t find it. Perhaps—”

“You’d have to see Dave,” said Johnny.

“He’s the young man who goes down in the steel ball? I—I’ve been watching you through the glass.”

“Yes, that’s Dave. He takes his work of exploring the sea’s depths very serenely! Tell you what!” Johnny exclaimed. “You get him to take you down!”

“In—in that thing?” The girl drew in her breath sharply, eyeing the distant shadow of the huge sphere.

“Sure, in the steel ball! He’d like to! He’s proud of it. And he likes showing people strange things. If you want someone to do a certain thing for you—ask him to do something else, first! That’s a grand rule.” Johnny looked into the girl’s frank, grey eyes, and decided he liked her.

“Yes—I—I suppose so,” the girl replied, slowly. “But you know—well, anyway—it’s worth thinking about!”

“Look!” said Johnny, starting up. “Perhaps you can tell me what that is.” He pointed to the distant island, where again the blinking green arrow could be seen.

“No, I—” The girl sat there, staring. “I never saw that before. But you know,” her voice dropped to a whisper, “there are spies on these islands! Lots of spies!”

“Spies?” Johnny’s voice expressed astonishment.

“European spies,” she added.

“But why?”

“I don’t know about it. Grandfather can tell you all there is to know. He’s always talking spies, and saying what they’ll do when the time comes.... You must come over and see us. Our place is just over there on the shore. You’ll come, won’t you?”

“Yes. Certainly I’ll come.”

“Thanks a lot.” Once more she gripped his hand. “And now—goodnight. I—I’m glad I came.” She was over the side and away.

“Well, I’ll be!” said Johnny as he settled back in his chair. A moment later, faint, and far away, he heard her voice come over the dark water:

“My name is Mildred Kennedy. Be sure to come see us—don’t forget!”

For answer Johnny whistled once, cupping his lips with his hands, to reduce the likelihood of arousing anyone on board. After that he was left to silence and the night—and the mysterious arrow of green light, blinking away on the distant hillside.

Sliding out the field glass, he studied that arrow for two full minutes. He felt sure from its strange blinking and winking that it was being used as a code signal. For the life of him, however, he could not make the lights separate themselves. They always remained a blur.

“Too far away,” he grumbled. He wanted to hoist anchor and let the boat drift closer to shore, but this, he knew, would not do. He was neither skipper nor mate.

Suddenly recalling Doris’ words of the previous night, he realized that he had made the light, the secret of the bright-eyed little Mildred Kennedy! “I won’t tell Doris about that!” he decided. “At least, not yet.”

He was seized with a sudden desire to know who was receiving those blinking signals of the green arrow. Deep in thought, he turned his back to the island and, to his utter astonishment, saw above the motionless sea some distance away, a second blinking green arrow!

“Ah!” he breathed, lifting the glass to his eyes. Digging into a pocket, he dragged out a pencil and a small notebook. After that, for fully ten minutes, he held the glass with his left hand while setting down numbers. 5 - 7 - 11 - 9, 13 - 6 - 3, 4 - 9 - 2 - 7. He wrote down figures and more figures, until a strange, rushing sound reached his ears.

Startled, he sprang to his feet. On the shore side he saw a broad band of white foam rapidly approaching the boat. Standing there, mouth open and staring, he watched it sweep toward him. With a hissing roar it swept beneath the boat and, without causing the least movement of the craft, went rushing on.

“False alarm,” he murmured. “Probably what they call a rip-tide.”

Turning back to sea, he looked again for the blinking green arrow. But it was gone. The distant island hill, too, now was entirely dark.

“Strange,” he muttered, as again he paced the deck.

And indeed it was strange, for the ship’s log had recorded no boat in sight at sundown!

From then, until Johnny’s vigil ended with the dawn, there was nothing to disturb the calm stillness of the tropic night.

CHAPTER IV
SPIES

On board the Sea Nymph was a small boat known as the Tub. Very short and broad, it rowed like a washtub, and in a storm, would have been about as safe as a