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ROY ROCKWOOD

THE SPEEDWELL BOYS IN A SUBMARINE
or THE LOST TREASURE OF ROCKY COVE

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BOOK FOUR IN THE SPEEDWELL BOYS SERIES

First published by Cupples and Leon, New York, 1913
This e-book edition: Roy Glashan's Library, 2018
Version Date: 2018-02-09
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"The Speedwell Boys in a Submarine," Cupples and Leon, New York, 1913



TABLE OF CONTENTS



Illustration

"There she be! There she be! She's st'arn on and bad smashed."



I. — SETTLING A NEW SCORE

THERE was a tiny red house, enclosed by a fence likewise painted red, which was set beside the shell road that ran along the bay shore, some five miles outside of Barnegat. The little house and fence were so red, and the shell road was so glaringly white, and the water which lapped the bulkhead was so blue, that the combination of colors was quite a patriotic display.

In the tiny yard was a flagpole, and at the foot of the pole was a grassy mound on which was mounted a small brass cannon. An old sailor with a wooden leg was on hand every morning at sunrise, and every evening at sunset, to "run up the colors," or furl them, and to touch off a sunrise and a sunset gun.

His name was Dick Billings, and people called him the Admiral, although he had never got any higher than gunner on one of the old frigates which saw their last days in our great Civil War. It was in an engagement in that war that Dick Billings lost his leg; he was now a pensioner of Uncle Sam, and although a very old man, was hale and hearty and lived quite alone in the little red house.

On this hot June day, when the house, and the road, and the bay contrasted their colors so brilliantly, Dick Billings, or the Admiral, was stumping along the road toward home with a basket of clams on one arm, and carrying the clam hoe in his other hand.

He had just climbed the bulkhead steps from the beach. There was a sharp turn here in the road, and around this turn, without warning, rushed a touring car at a speed of not less than twenty miles an hour.

It caught the Admiral on the port side—that was his wooden legged side—the clams were strewn along the road, and the old man was left in the middle of the highway, quite helpless on his back. The fellow driving the car, and the crowd in the tonneau, laughed at his plight and did not even slacken speed.

"Come back here, ye lubbers! Ye've busted me leg!" bawled the old sailor, and he lay there waving his arms and one good leg much after the fashion of a turtle on its back, trying to turn over.

Round the turn sounded the sudden tooting of more than one horn—a rush of wheels—the popping of an exhaust.

"Look out!" yelled a voice.

It was the leader of a company of lads on motorcycles who appeared, and the moment this youth saw the old sailor lying in the dust of the road, he stopped his engine and hopped off. The other boys with him did the same.

"Here's a pretty mess!" ejaculated the leader of the party of riders, who all wore caps lettered "R. O. C." "This is some of Chance Avery's work, I'm certain."

"Perry Greene never should have let him take his motor car, Dan," said one of the other fellows. "He knew that Poole had refused; and of course Chance couldn't get the Stetson car. Burton Poole and Larry Stetson have turned Chance down hard. And now he's racing over the roads with that crowd of chums of his from the Greenbaugh Seminary—see what he's done to this old man."

The first youth had already gone to the prostrate sailor's assistance.

"Are you hurt badly?" he asked. "How can we help you?"

"They've busted my leg! They've busted my leg!" repeated the sailor.

"Why, that's the Admiral, Dan," cried one of the other boys, coming up swiftly.

"That's who it is, Billy Speedwell," rejoined another.

"One of us ought to go for a doctor," suggested a fourth boy.

The Admiral burst out with:

"Don't ye bring no sawbones here, ye lubber!"

"Better make a trip to the lumber yard," chuckled Billy Speedwell. "See, it's his timber leg that's busted all to flinders. Buck up, old hero. We'll get you home, and find you a crutch."

"You've got some sense in that head o' yours, lad," declared the Admiral. "Two of ye give me a flipper each and I'll hop home all right. Lucky I've got another leg. That feller'd run inter the house and busted that leg, too, if he'd knowed of it, I s'pose."

But Dan Speedwell, the leader of this party of youths belonging to the Riverdale Outing Club, who were on a Saturday afternoon run, was still serious over the affair.

"What did the leg cost you?" he asked.

"A five dollar bill, my lad."

"It would have been the same, Monroe," Dan said, turning to Monroe Stevens. "It would have been just the same to Chance if he had really broken the old man's bones. He would have driven on, and laughed. He did drive on, and laugh, without even finding out how badly his victim was hurt. He'll have to pay for the wooden leg, at least."

"He's a scoundrel," admitted Monroe and Wiley Moyle, together.

"He's that," growled Biff Hardy, a burly young fellow who was riding a new Flying Feather, the pet make of the Darringford Machine Shops, of Riverdale, in which Biff worked.

Billy and Jim Stetson lifted the old sailor to his feet. They had collected his basket of clams and picked up the hoe, and now the two younger lads helped the Admiral to hop along toward the little red house.

Dan went to his wheel again and righted it.

"I'm going to catch that car," he said, "and Chance Avery is going to settle for this right now."

"I'm with you!" ejaculated Monroe, who was a very peaceable young fellow, but who was stirred by this meanness of the brother of the superintendent of the Darringford shops, just as Dan was.

"I reckon the rest of us can keep those college cut-ups off while you settle old scores with Chance," said Hardy, grimly, as Dan mounted and rode off.

Dan and Billy Speedwell were famous riders of the motorcycle in their county. In a former volume of this series, entitled, "The Speedwell Boys on Motorcycles; Or, The Mystery of a Great Conflagration," are narrated some of their adventures, and speed trials at the Compton Motordrome, and elsewhere.

Later, the brothers, who were sons of a small dairy farmer living on the outskirts of Riverdale, obtained possession of a racing automobile and the story of how they won the thousand mile endurance test is told in "The Speedwell Boys and Their Racing Auto; Or, A Run for the Golden Cup."

In "The Speedwell Boys and Their Power Launch; Or, To the Rescue of the Castaways," is related the story of the regatta of the Colasha Boat Club, and how Dan and Billy obtained their launch, the Red Arrow, and the many adventures they had in her.

Chanceford Avery was a youth who had long shown his enmity to the Speedwells, and had tried to rival them on the motorcycle, in driving a racing auto, and on the river. He had never shrunk from seeking, in underhanded ways, to take advantage of Dan and Billy.

Dan Speedwell was not quarrelsome, and thus far he and Chance had not come to blows. There had been a single former occasion when Dan was tempted to personally chastise the mean-spirited Chance—or, at least, attempt the feat. Chance was something of an athlete, and a skillful boxer.

But now, the cruelty of the bully—the manner in which he had deliberately knocked the old sailor down, and left him helpless in the road—had roused Dan Speedwell's anger. He was bent, when he started from the little red house, on trailing the racing auto along the shell road, and forcing Chance Avery to—in part, at least—pay for the damage he had done.

Dan and Billy, with their fellow members of the outing club, had gone to Barnegat on an informal run. While in that seaport town they observed Chance and his chums, who had borrowed an automobile; but they had carefully kept away from the hilarious crowd of would-be "sports."

When the Speedwells and their comrades were some distance out of Barnegat the automobile passed them at racing speed; but although the car had more than five minutes start when Dan Speedwell left the spot where the Admiral had been bowled over, he had no fear that he could not overtake Chance and his friends.

Dan was soon traveling almost as fast on this country road as ever he had on a track, and it was not long before he saw ahead the auto guided by Chanceford Avery. Some of the fellows in it looked back and saw the racing cycle. They called to Chance that they were being pursued, and the reckless chauffeur let the auto out to the limit.

Dan was already going at a pace that spelled peril in every yard he traveled. Suddenly he heard an explosion and a series of yells. The auto started to climb an embankment beside the road as Dan shut off his own engine and pulled out to the other side.

Chance had the presence of mind to put on brakes and the auto struck a small tree, glanced from it, and then rolled back into the road. One of its forward tires had burst. The race was over.

Dan stopped his motorcycle directly beside the car.

"Hullo!" ejaculated Chance Avery, with his usual lowering look. "What do you want, Speedwell?"

"I want you," Dan returned.

"Huh! what's the matter now?"

"You know what you did to that old man back there. You're not going to escape scot-free this time—not if I can help it."

"Who made you a constable, I want to know?" demanded Avery.

"I'm not a constable. I'm just a fellow who has seen you do so many mean tricks that he's made up his mind that you shall pay for this one, Chance Avery. I want five dollars for the Admiral's wooden leg—and I want it now!"


II. — THE ADMIRAL'S TALE OF TREASURE

BILLY SPEEDWELL and Jim Stetson managed to get the wrathful old sailor to his door, which he unlocked with a huge key, and then into a big armchair in the tiny kitchen. Everything inside the house was arranged as snugly and compactly as though it were a ship's cabin.

"Come along, Billy!" said Jim, hastily, wishing to get away before they could be thanked, and likewise eager to follow the other boys. He ran hack to the road and got astride his motorcycle at once; but Billy waited to see if he could do anything more for the old man.

The Admiral was unstrapping the shattered remains of his wooden leg. Billy asked:

"Where's your new leg, Mr. Billings?"

"Avast there," rumbled the Admiral, in his deepest tones. "Don't ‘Mister' old Dick Billings. He ain't used to it. He don't like it. 'Specially from a little chap what's done him a good turn."

"All right, Admiral," laughed Billy. "If you like that better."

"I'm Admiral by brevet," said the sailor, gravely. "Them that likes me round here calls me that. I don't mind."

"But the leg, Admiral?"

"It's stowed in the lazarette, son," said the sailor. "Jest open that hatch yonder and ye'll see a ladder. There's a ship's lantern already lit yonder—I keeps it so, my lad. Never know when ye might need to go below—and there ain't no winders in the lazarette."

Billy knew that he meant the cellar. There was an iron ring in the middle of the floor, which floor was holystoned to the whiteness of chalk. Billy took hold of the ring and pulled up the trap. A musty odor arose from below.

"Jest swing down there with the light, son," went on the Admiral. "You'll find a new timber-toe lashed to the for'ard bulkhead."

The spare "timber-toe" hung in the bights of two tarred ropes. The boy secured it and came back through the hatchway to the "main deck" of the cottage. The wooden leg was merely a round stick of timber, worked on a lathe, with a ferrule at the small end, and the large end hollow.

When Billy came up with the wooden leg he saw that the Admiral had finally kicked off the broken one and that he sat in the armchair with several legal-looking documents, and a much-worn old wallet in his hand. These he thrust into the hollow of the new leg before he proceeded to strap that implement upon the stump of his amputated limb.

"That's a safer place than any dunnage bag to keep your private papers in, lad," the Admiral declared, cheerfully. "There ain't likely to be any thief or other landshark get your money and your papers, out of that place."

"I should think not," agreed the amused Billy.

"And ye mustn't think old Dick Billings ain't carried a-plenty of vallibles in that same place, neither. It were in this here werry leg that them sculpins busted all to flinders, that I carried my share of the Dardanelles emeralds, in '76. My share warn't much, mind you; we shared accordin' to our standin', and I warn't rated high on the Fannie Hendricks. Jest the same, my emeralds bought this sand lot and built this trim cabin for my old age. Ah," added the old seaman, "them emeralds was beauties."

Billy Speedwell's eyes began to grow big, and lie sat down.

"Tell us about it, Mr.—er—Admiral," he urged.

"Didn't I ever tell ye? No! you ain't one o' these ‘long shore sawneys,' air ye?"

"I live in Riverdale," said Billy. "I never was in your house before."

"Well, I like you and your mates," said the Admiral, heartily. "Where'd the rest of 'em go?"

"My brother says he's going to catch that car and make the fellows who ran you down pay for your leg," declared Billy.

"Eh? I hope he does. He oughter be keelhauled and then warmed up with the cat some," growled the Admiral, savagely. "Come, pass me that 'baccy jar, boy. I'll fire up. Then I'll spin ye a yarn that'll make yer hair curl more'n it does now," and the Admiral chuckled as he stuffed the tobacco into the bowl of his very black pipe.

"Ye see, it was afore my last enlistment," he pursued. "I never sarved but one term on these here iron-pots they call warships now. Don't like 'em. Give me the old wooden frigates—a reg'lar ship of the line. Men aboard them old boats was sailors; now a navyman is a machinist, or a boilermaker—I dunno which," added the Admiral, in a very much disgusted tone.

"Well! I'd just been paid off from the old Yorktown and thought I didn't want no more marking time in these here man o' war vessels in time o' peace. We'd a chief gunner paid off at the same time, and a slather of others. This chief gunner was named Marksman.

"This Marksman was never a commissioned officer; but he come from highclass folks, jest the same. There was something wrong with him; but we liked him, and so did the brass buttons as well. Why, almost everywhere we touched in the old Yorktown (and we made two clean voyages around the world in her) the consuls and such, at foreign ports, seemed to know Marksman, and had him to dinner, and the like. He was as close mouthed about himself as a clam.

"Howsomever, he was paid off same as me and the others. He got us together in a room in a seaman's lodging, and he put a project before us. It was all about a bucketful or more of jewels that he knew about, hid on a little island at the mouth of the Straits of Dardanelles.

"He didn't tell us all the particulars of how he knowed so much about them. Some scientific sharks had been digging in that island to find a buried city, or the like. Mebbe you, sonny, going to school, know something about such things," said the Admiral. "I never got so I could much more than sign my name to the ship's papers."

"They do excavate old cities and get wonderful pottery and ancient records, and coins, and such out of the diggings," said Billy.

"Yes. Well, while the Yorktown was around them waters, Marksman had gone with a party into one of these excavations," continued the old sailor. "He had got lost from the rest of them, and with a workman's pick he had started to dig a way out. He had broke into a sort of secret chamber, or the like, in one o' them old, old houses, hurled so many ages, and he'd come across a great vase filled with emeralds. They was beauties. He showed us a handful he had taken before he closed up the hole he had made and then pulled down some rubbish before the wall, to hide it.

"Marksman was eager to go back. He said it had to be done secret, and there would be some fighting. The Turks who owned that part of the world made them scientific sharks give up everything of any value that they found in the diggings. At least, that's what Marksman told us.

"Well," said the Admiral, puffing away at his black pipe, while Billy's eyes grew rounder, "his idea was to charter a steam sloop that was then lying at Naples. He knowed all about her. We was to travel steerage from New York to the Italian seaport on one o' them big emigrant steamships, get the steam sloop there, provision her, get clearance papers for Alexandria, or Suez, or some place that we hadn't no intention of going to, and slip around to the Dardanelles.

"I warn't a young feller then, nor I warn't an old one. But I was a jolly reckless one, just the same," declared the Admiral. "The thing looked good to me. It looked good to all of us but Sim Pettengrew. He wanted to get married and buy him a farm, and he done it with his paycheck. The rest of us went along with Marksman.

"He made us get old and queer duds to travel to Italy in, and we went aboard the steamer separate, and made out we didn't know each other. I tell you it was a hard voyage. I'd never sailed in any ship before that I didn't have to help work. And being kept under hatches, as it were, was tough. Why, I was as sick as any sawney I ever see—and so was most of the others.

"I dunno as we'd have passed for a crowd of dagoes, what we was meant to represent," went on the old seaman, reflectively, "but I'm sure them officers never thought we was old tar-handed, salt-junk eaters from Uncle Sam's navy. We acted more like a party of farmers taking our first voyage.

"We crawled ashore at Naples, and we'd had such a hard voyage that we made Marksman gives us freedom ashore for a while. Of course, during that freedom we spent every cent we'd brought off the Yorktown with us.

"We was to share according to our stations," continued the old sailor. "My part was one-fiftieth of the whole. We got it, I tell ye—yes, sir-ree! I sold my emeralds and bought this place and had some money left. I made pretty near two thousand dollars out of the emeralds, and got cheated at that."

"Then the treasure in all was as much as a hundred thousand dollars!" gasped Billy.

"I shouldn't wonder if it was more. We never counted all them emeralds. I got mine by grabbing for them, like you'd try your luck in a grab-bag," declared the Admiral.

"Grabbed for them!"

"Aye, aye," said the old sailor. "Give me that jar again, lad. I'll tell ye about that—and how we found the cave in the lost city, got the bucket of emeralds, and tried our luck runnin' of the Turkish patrol-boats with that same steam sloop."


III. — THE MYSTERY OF ROCKY COVE

"I HAD a timber-toe in them days," said the Admiral, "but I was lively on it. Marksman was glad to have me go along as bo'sun. Everhard—Tom Everhard—was mate o' the Fannie Hendricks, which was the name of the steam sloop Marksman chartered at Naples.

"She was a mighty fine craft—had belonged to an English lord who'd had a bad time in her in the Adriatic, and come into Naples and put her in the hands of an agent to be chartered, or sold, while he went home overland. He'd got enough o' blue water, I reckon," pursued the Admiral.

"We got away just as Marksman planned. He was navigator—and a good one. I never knew what brought that man down in the world; but he was a fine skipper and knew all the ropes, I tell ye! The Fannie Hendricks made a quick v'yage around Sicily and the Boot of Italy and up through the archipelago. We touched at night at a little fishing port on Ambros. The island where the scientific sharks had done their digging wasn't a dozen miles away.

"Here Marksman took up a feller who, it seemed, knew all about the excavations. He was a snaky Greek; but Marksman trusted him and seemed to have some hold on him. Some said the Greek was a bandit, or a political refugee. Anyway the Turks wanted him, and he hated the Turks.

"So we hid the sloop by day and then shot over to the right island the next night. It was a black night—now I tell ye, lad! When we went ashore in two boats, the Greek had 'em fastened together with a cable so that they wouldn't get parted in the darkness. He went in the bow of the first boat, passed the course back in a whisper, from man to man, the feller steering the first boat whispering to the bowman in the second, and so back to Marksman, who held the ropes in the starn of the second boat.

"We got ashore all right—on the blackest kind of a shore, all rocks it were, over which we scrambled. The Greek had made us wrap our gun-butts in rags so't they wouldn't rattle on the stones, and we went up that shore and into the interior of the island like a troop of cats crossing hot ashes," chuckled the old seaman.

"It seemed the Greek knew a secret way into the buried city—a tunnel known to the old inhabitants of the island long before the scientists opened their main shaft. This tunnel was digged right from the hut of a goatherd who lived back from the water a piece. And we got to this hut all safe.

"The Greek and Marksman went forward to spy out the lay of things. Good they did. That goatherd, all unknowin' that his friend was comin' visitin' with about two dozen Yankee treasure seekers, had a Turkish soldier in to supper. Or, the Turk had happened along and invited himself to supper. We never knowed the rights of it.

"When the Greek and Marksman peeked into the window and seen the soldier, they made up their plan mighty quick. The Greek made a disturbance among the goats and the herder come out in a hurry. The soldier was left tied and gagged.

"We'd brought lanterns and tools and I dunno what-all. Marksman was a man of forethought as well as of courage. That trick was bound to go through under his management—and so it did. The Greek led us to the part of the diggings where Marksman had burrowed through the wall and then hidden the traces of his work. The place had not been disturbed, although his previous visit was eighteen months before.

"We dug through the rubbish and found the loose bricks—four-square bricks they was, all cracked and seamed, and made of blue clay. We got 'em out with bars. We broke into the chamber Marksman had found by accident, and there was the tall, lean-necked vase, just as he had told us about it. The emeralds was in it, too. Nobody had disturbed them, for the scientific sharks, nor yet the hungry Turks, hadn't found the place.

"We picked up some odd coins, but there was nothing else. It looked as though the ancients had cleaned out the treasure chamber, all but the vase, when they deserted their city for whatever cause. The emeralds had been overlooked. We didn't overlook 'em," added the Admiral, grimly.

"Well, lad, we stole out of that place so them Turks didn't either see or track us. Not till after we got back to the goatherd's cottage, anyway. Then it seemed that this soldier we had tied up should have met another guard along the beach a ways. The soldiers girdled the island at night, and this feller not turning up, his mate come to the hut for him.

"We got out just in time. Our man and the other guard exchanged shots with us, and then the Turk ran for reinforcements. We legged it for the beach. A file of Turk soldiers came and riddled the goatherd's hut before they found out we were out. We got the boats off by the flashes of their guns.

"Then we pulled out of gunshot before they scrambled around and got a patrol boat. She was a fast one and the Fannie Hendricks had to do her best. They chased us till morning, and then a fog came up and we dodged them. But the whole archipelago was alive with Turkish craft, and the thing that finally saved us was the fact that they didn't know just what sort of a boat we had, nor what flag she was sailing under.

"And as soon as we got out of the archipelago into the reg'lar Mediterranean Sea we changed our flag," said the Admiral.

"We run up the British jack instead of the stars and stripes, and streaked it for the far end of the Mediterranean just as fast as the Fannie's engines would take us. We sailed through Gibraltar Straits and made a Portuguese port.

"We was all for waiting till we got to the States before we divvied up. Marksman's share was to include the sloop, and I was going to stick to her as bo'sun," said the Admiral. "So we sails our pleasant voyage, makes a good landfall, and comes poking up this very coast one windy night in June, '76."

"Not right here—not this bay shore?" gasped Billy.

"Not far from it. We made the light below Port Luther at sundown. Marksman knowed Rocky Cove——"

"Right back of Wild Man's Island!" cried Billy.

"That she is," agreed the Admiral.

"Why, Dan and I have been there in the Red Arrow," said the boy.

"You know how the land lies there now," said the old sailor. "But Rocky Cove was different in '76."

"How different?"

"Them cliffs, jest like Wild Man's Island," said the Admiral, "is all honeycombed with caves and the like. Washed out by the water long ago, they say."

"Yes," agreed Billy.

"Well, lad, in the day I speak of, Rocky Cove warn't jest as it is now. Ye know where's what they call ‘The Slide'?"

"Yes, I've heard my father tell about it. There really was a shifting of the earth there. The edge of the cliffs on that side of the cove broke away and the land slipped into the water. The cove used to be a whole lot bigger than it is now."

"That's true as gospel," said the Admiral, nodding his head gravely. "And the steam sloop Fannie Hendricks, and Marksman, her skipper, is under that slide!"

"Oh, Mr. Billings, you don't mean it?" cried Hilly.

"Yes, I do. I'll tell ye, lad," pursued the Admiral. "We run into Rocky Cove that black and windy night. We anchored in a deep pool under the overhanging cliff. Them that was going to leave her agreed to leave in the morning; and then Marksman was going to dock the sloop, have her repainted, change her name, and just wipe out all record of her flight across the Mediterranean and the Atlantic. That was the scheme.

"But we was disturbed by the rocks sliding before midnight. We was kept awake, and was on deck. The wind fell finally and it became almost a breathless night. It seemed as though the sloop was perfectly safe there, for we all thought the queer sounds foretold a hurricane.

"Then the first crack came, a part of the cliff pitched forward, and came rumbling down into the sea, and the Fannie was shut into that little pool 'twixt the wall and the reef o' rocks, and there was no escape for her.

"The smashing of the rocks, and the fountain of water that was splashed up, was something awful. It scared every man Jack of us," said the old seaman, nodding. "The deck was a-wash three foot deep with the waves. She rocked like the falling stones had hit her, although not one fell upon her deck.

"And all the time the rocks above were growling and threatening, and we knowed more was coming down. The men was mad to get ashore. There was still a chance to escape. Marksman didn't stop 'em, but he said he'd stick to the sloop himself.

"‘I have failed in everything I ever attempted but this,' I heard him say. ‘I've accomplished this. I got the emeralds, and I got 'em home. Now I stays by 'em! You fellows can take your share and go.'

"But many of us was too scared to wait for the jewels to be divided. You can't realize how awful the grinding of the rocks sounded, lad. Some of us, I reckon, would have give up our share of the treasure if we could have wished ourselves in Port Luther, or even at Rickett's Light. But the others wanted a part of the loot. And Marksman wouldn't go ashore.

"‘Every man grab a handful and go,' he said, finally. We agreed, and we warn't long a-doin' of it. But the mouth of that vase—or, rather, the neck of it—was mighty small," and the Admiral held out his big hand, clutching the air, and grinning.

"There was them that grabbed afore me," he said. "When it come my turn I tried to get all my fist would hold, and then I'd had to break the jar to get my fist out. So I had to content myself with a small handful, and so did the others. Them emeralds was strewn along the deck like they was marbles, whilst we thrust our fistfulls into our pockets and ran for the boats.

"We couldn't get Marksman to leave, so he and the Fannie Hendricks was right there when the bulk of the cliff fell," said the Admiral, after a moment, and speaking more gravely. "We was then half a mile up the beach and running as last as our legs could carry us. There warn't no use telling about the craft and her skipper. Besides, we didn't know what the authorities would say to us and the emeralds. So we give out that we'd lost our boat, and the folks around there thought it was just a fishing craft.

"That's all the story, lad. Marksman and the Fannie are buried under thousands and thousands of tons of rock, and the emeralds are with him. For we brought away with us a mighty small share of what was in the vase. Yes, sir, right nigh here—not thirty miles away—lies a fortune for the one that can l'arn how to get it. Some day, like them scientific sharks was burryin' inter that uncient city on the island at the mouth of the Dardanelles, other folks will dig inter the Slide at Rocky Cove and find the sloop, and the emeralds—and Marksman" concluded the old fellow, shaking his head.

The end of the story of lost treasure left Billy Speedwell as excited as though he had been a participant in the reckless adventure just related by the old sailor in the tiny kitchen of his little red house.


IV. — A SPECIAL BY WIRELESS

MEANTIME there was quite as exciting an incident transpiring some miles away upon the road to Riverdale, and Billy's brother, Dan, was an important character in this happening.

"You are going to pay for that leg, Avery—or take a thrashing," Dan Speedwell declared, as Chance Avery stumbled out of the automobile.

"Get out of the way," growled Chance, making a threatening motion with the wrench he had taken from the toolbox. "I haven't time to fool with you. We've got to get another tire on, boys," he said to the seminary students, who likewise piled out of the borrowed car.

"You can put on a new tire later," said Dan, firmly. "You'll attend to me, just now."

"What's the matter with this fellow, anyway, Chance," demanded one of his friends. "Why don't you hit him one?"

"I will if he keeps on getting fresh around here," declared Chance.

Dan deliberately stepped into the other's path again.

"Don't waste time threatening, Avery," he said. "You will pay for the old man's wooden leg right now."

"Why, he's guying you, Chance," cried one of the lads. "If you don't whang him one, I will."

This fellow swung a blow for Dan's head, but the latter side-stepped and avoided it.

"You fellows can afford to stand by and see fair-play," Speedwell observed, with scorn. "There are enough of you."

"Oh, get out!" snarled Chance Avery, and he pushed Dan away with his shoulder.

"I am going to make you pay for that leg, Avery," declared the captain of the Riverdale Outing Club. "Get out your money."

Chance lunged with his shoulder again, as he half bent over the exploded tire.

"Stand up!" commanded Dan, sharply, seizing the other by the collar and jerking him around.

Chance uttered an angry yell, sprang at his opponent, and swung the heavy wrench above his head. Dan did not flee, but stepping in close to him, so that the cowardly blow passed beyond his head and Avery's arm crashed down upon his shoulder, he delivered a short-arm jab that landed with a hard jolt directly under Avery's left ear.

Chance crashed against the wheel of the car. His mates yelled. He lost his hold upon the wrench, but two of his friends sprang to seize Dan before the latter could repeat the blow.

At the moment, however, in a cloud of dust, Biff Hardy and Monroe Stevens reached the spot. Biff leaped from his wheel, caught the two attacking Dan from the rear, and swung them around, throwing one in one direction and the other in another—and with force enough to bring them to hands and knees on the hard road.

"One on one!" roared the big fellow. "Take a lad of your size. Don't two of you pitch on one chap, for I won't stand that!"

"Hey, Fred!" exclaimed Dan, speaking to Hardy, the space about himself and Chance having thus been vigorously cleared; "don't make it one against two, yourself. And please keep out of it, you fellows. This is strictly between Avery and me. He is going to pay for the old man's wooden leg—five dollars. He is going to pay for it now, or there's going to be trouble."

"I don't want to spoil my hands with you, Speedwell," choked Chance, feeling tenderly of his neck where Dan's sturdy fist had landed.

"Then the way to keep your hands clean," said Dan, scornfully, "is to pull out your wallet and make good for the leg. And you're getting out of it easily at that. If I was the Admiral I'd have you in jail for reckless driving."

"Whoever made you collector for the old duffer?" snarled Chance.

"Me—myself," laughed Dan. "Come on, find the money. There must be five dollars left among a bunch of sports like you and your friends here. And we're going to have the price of a new leg for the Admiral if we have to pick you all up and shake it out of your clothes."

"You're right, Dan!" cried Hardy.

"I'm with you," said Monroe, and so said Wiley Moyle and Jim Stetson, who had just ridden up.

Chance Avery plainly shrank from any game of fisticuffs. Dan Speedwell seemed altogether too willing to try issues with him in that way. And the members of the Riverdale Outing Club looked to be quite able to back Dan up and polish off the whole crowd from Greenbaugh Seminary. Chance slowly pulled out his pocketbook and handed over the five dollars.

"All right," Dan said, crisply. "I'll ride back and give this to the old fellow right now. Billy and I will overtake you fellows later." Then he added to Chance: "I'm almost sorry you didn't try conclusions with me, Avery. Some day it has got to come, and although I'm not looking for trouble, I advise you to steer clear of me in the future—and try, in addition, to behave yourself along the public road."

Dan Speedwell raced back to the little red house, reaching it just about as Billy was bidding the Admiral good-day. The old fellow was delighted to get the price of his broken leg so easily, and so quickly, and he warmly invited the brothers to come and see him again.

"I'll tell ye some more yarns, lad," he said to Billy, chuckling. "You seem to take to 'em."

Billy, excited over the story of the Dardanelles emeralds, repeated it to Dan as they wheeled homeward, and it was, indeed, the principal topic of conversation between them for some days following.

"Well, whether the Admiral made up the yarn, or it is true, it's mighty interesting," was Dan Speedwell's comment. "Next time we get a chance to run outside in the Red Arrow, I'd like to go around to Rocky Cove and look over the Slide. Maybe he made it all up; but it sounds very realistic," he concluded.

"True? Of course it's true!" cried Billy. "That old sailor is all right, I tell you. And any, wouldn't it be great if we could find some way of getting at that vase of emeralds in the cabin of the sloop!"

"Blasting out the rock and rubbish that fell down from the cliffs in 1876; eh?" laughed Dan.

This was on the Monday evening following the day Billy had heard the wonderful story of the treasure of Rocky Cove, and Dan had so thoroughly cowed Chance Avery. It was a warm, delightful evening, the boys had done the chores, and were sitting on the grain-room steps. They suddenly heard the popping of a motorcycle coming up the road from town, and in the moonlight there soon appeared a rider rapidly approaching.

"It's one of the fellows," declared Billy, jumping up. "And he's turning in here."

"It's Wiley Moyle," said Dan.

It was Wiley, and Billy hailed him the moment he leaped off his wheel and came running to them.

"I got something for you," he cried.

"Out with it," advised Dan, seeing Wiley tugging at something in his pocket.

"It's a message," explained their chum. "Jim Blizzard, of the Riverdale Star, sent it. He said it was a wireless from Rickett's Point; the operator at the station there repeated over the long distance 'phone to Mr. Blizzard, who wrote it down."

Wiley worked in the newspaper office after school hours, and now that the long vacation had begun he was putting in most of his time there. That was how he had earned his motorcycle.

He thrust the envelope into Dan's hand. Dan ripped it open and the moon was so bright where they stood that it was easy for both he and Billy to read what was written on the paper. It was rather startling:

"A. C. wants you immediately. Message rec'd at Ricketts' 6:50."

"Hullo!" ejaculated Dan.

"There's something doing," whispered Billy, eagerly.

"I believe you," responded his brother.

Wiley was looking on with great interest. He said:

"I reckon that's from Wild Man's Island, isn't it? I thought so. Is Mr. Craig going to astonish the world at last? My father says he's just as crazy as he can be. Is he?"

"Not so you'd notice it!" growled Billy, while Dan started for the house. "Going to fix it with the folks, Dan?"

"I'll speak to father. You get out my motor and your own. We'll have to go, of course. We promised."

"What is Mr. Craig doing over there?" asked Wiley Moyle, with curiosity. "He's leased Wild Man's Island from the estate that owns it, and won't allow anybody on it, so they say."

"It isn't our secret," said Billy, gravely. "We only do errands for him in the Red Arrow."

"Seems to me he bosses you around a good deal," said Wiley.

"And why shouldn't he?" demanded Billy, with some warmth. "He gave us our power launch."

Meanwhile he was getting out his own, and Dan's, motorcycles. They had been cleaned and put in perfect order since their Saturday afternoon run to Barnegat.

"Do you fellows really mean to run clear out to Wild Man's Island to-night?" queried Wiley.

"Yep."

"Will your father let you? What'll he do about the milk route in the morning?"

"He and the hired man will 'tend to it," said Billy, hastily. "Father knows that Mr. Craig has a right to call on us if he needs us."

"And we'd be mighty ungrateful if we did not respond," added Dan, who had returned in time to hear this last. "He says his need is urgent, so we must hurry."

"I've half a mind to ask to go with you," said Wiley.

"Think better of it, old man," laughed Dan. "We couldn't take you—not this time. We have promised never to bring anybody to the island in the launch without Mr. Craig's permission."

Already the Speedwell boys were astride their wheels and before Wiley Moyle knew whether or not to be offended by this refusal, the popping of the engines showed that Dan and Billy were well under way.

They shot out of the yard and took the crossroad toward the river. It was not far to the Colasha, and the dock where they kept the Red Arrow, the power launch that Mr. Asa Craig had given them; and it was down hill for a good part of the way, too.

So it was that Dan and Billy came to John Bromley's wharf, running so silently that nobody could have heard them. Old John had rigged a stockade fence and gate at the head of his dock, and nobody could get out upon it from the landward side without ringing him up, unless they possessed a key to the gate, as the Speedwells did.

Dan and Billy, not wishing to arouse the old fisherman, who was likewise their boatkeeper, opened the gates softly and ran the motorcycles out upon the wharf. John's little cottage was all dark, and it seemed as though nothing was stirring about the place.

But suddenly Billy, who had gone ahead, while Dan softly closed and locked the gate again, halted and said:

"Hist!"

"What for?" chuckled Dan. "Who'll I ‘hist'?"

"Sh!" exclaimed Billy. "Don't you hear it?"

Dan waited a moment; then he heard plainly the creaking of oars in a boat. The noise drew nearer while they waited.

"Somebody coming to the dock," whispered Billy.

"Old John has been out, perhaps, and is just coming in," said Dan.

But the boys remained very quiet, nevertheless. They leaned their wheels against a pile of lobster-pots and stepped softly down the long wharf. They heard the oars cease, and then came a little bump and jar as the rowboat collided with one of the spiles.

"Right beside the Red Arrow" whispered the anxious Billy.

As he spoke the boys were startled by the appearance of a tall figure on the stringpiece of the dock just ahead of them. It did not rise out of the boat that had bumped against the wharf, although it stood poised above this strange craft. And, in a few seconds, both Dan and Billy realized that what made the figure seem so tall was the fact that it held something above its head at arms' length.

Out of the shadow of the fish-house this figure had sprung. It held the heavy object poised above its head for a moment only. Then the weight was sent crashing into the bottom of the rowboat, while the hoarse voice of Old John roared:

"Take that now, ye consarned river pirate! I got enough of you, sneaking about my wharf and trying to board that launch!"

The occupant of the boat, without a cry or an answering word, scrambled away from the dock—the boys could hear the uneven beat of his oars and the splashing of the water as he pulled away. Dan and Billy ran forward and asked the old fisherman what had happened.

"Hullo, boys!" returned Bromley. "It's them fellows after the Red Arrow again."

"Not trying to injure the launch?" gasped Billy.

"Trying to board her, anyway. I dunno what for," said Bromley; "but not for good, you may be sure."

"Who is it?" asked Billy.

"Now you've asked me a hard one," said the fisherman. "But he was here Saturday night and I chased him away. Last night I watched, but he did not come. To-night I jest heaved a stone into his old boat. I bet she started the planks in her bottom!" and Old John began to chuckle.


V. — DAN GOES OVERBOARD

EXCITED as the Speedwell boys were over the prospect of their night trip to Wild Man's Island on the Red Arrow, the fact that some ill-disposed person was hanging around the dock where the launch was kept disturbed them not a little.

"And you have no idea who the fellow was, John?" asked Dan Speedwell, seriously.

"I didn't get a fair look at him," returned the old fisherman.

"I guess I know who it is," said Billy.

In fact both boys immediately suspected the identity of the marauder.

"We can't prove it was Chance," said Dan, calmly.

"That feller's a bad egg," said Old John Bromley. "But I'll catch him yet."

They cast off, and Old John shoved the launch away from the wharf. The outgoing tide caught her and she drifted rapidly away. Billy went to the steering wheel, while Dan attended to the motor.

He turned the switch and revolved the fly-wheel.

The screw began to turn, and the launch gathered headway. Billy pointed her nose more directly down stream and the voyage was begun.

Before they had gone half a mile from the dock Billy suddenly yelled to his brother:

"Shut her off, Dan! I hear something."

"What's the matter now?" demanded the older Speedwell, obeying Billy's request.

Then it was that both boys heard the cry repeated—a shout from somewhere out on the river—and not far from the launch.

"Somebody in trouble out there, Billy," cried Dan.

"So I thought."

"We'll go over yonder and see who it is," declared the older lad. Billy swerved the launch to port, while, above the staccato explosions off the engine they heard the voice again.

"Help! help!"

It was a cry of real distress—no doubt of that. Dan darted into the cabin, and came out again with a megaphone which he used in replying to the hail:

"Ahoy! hold on; we're coming!"

Again and again Dan shouted. The replies grew louder as the Red Arrow rushed on. Suddenly Billy whirled his wheel, and the launch changed her course sharply. He likewise cried to his brother:

"Dead ahead, Dannie! Look out for it!"

His brother leaped up and tried to pierce the gloom. There was a white speck ahead. Something waved above the river's surface, and again the tremulous voice cried:

"Help! Help!"

It ended in a gurgle. Dan knew that the wave cast up by the flying launch had gone over the struggling victim. He had sunk.

"Stop her, Billy!" yelled Dan, and without waiting to more than kick off his canvas shoes, the Speedwell lad went overboard.

He had dived deeply. The blood began to pump in his ears and the pressure on his lungs was painful. Therefore he had to kick his way toward the surface again.

And, as he did so, shooting up like an arrow from tile depths, his outstretched hand came in contact with an object that he gripped tightly. It was the sleeve of a man's jacket. In diving he had gone deeper than the drowning person.

Dan dragged the victim to the surface with him. Being a strong swimmer he found no difficulty in doing this, and he held the victim's head above water.

Dan shouted again and again, and Billy was able to bring the Red Arrow directly to the spot where his brother was struggling. He shut off the power once more as the launch ran alongside the two in the water, and then sprang to the rail with the boathook.

"All right, Dannie?" gasped his brother.

"Yes. Steady, boy! Take this chap first."

"Who is he?" demanded Billy, as they got the unconscious victim of the accident alongside the launch.

"Ask—ask me an easier one!" exclaimed Dan.

Between them—with Billy lifting and Dan shoving from below—they got the half-drowned chap over the rail. Dan, pretty well blown himself by that time, swarmed inboard, too, and lay panting on the deck.

Before Dan himself was able to sit up, the fellow he had rescued struggled into a sitting posture. He cried:

"Oh! the boat's gone!"

Billy uttered an ejaculation and exclaimed:

"See what you pulled out of the river, Dan. It's Chance Avery!"


VI. — "THREE IS A CROWD"

DAN was as surprised as his brother over the discovery of the identity of the victim of the river accident. But he only said, when he got his breath:

"Take the wheel again, Billy. Let her run slowly until I can shift into some other togs. He'll have to have some dry duds, too."

"He won't put on any of mine," exclaimed Billy. "Why, Dan, he's the one who has been around Bromley's wharf. The rock John heaved into his boat set it aleak."

This the younger boy whispered in Dan's ear; but all Dan said aloud, was:

"Your clothes won't fit Chance, anyway, so don't worry. I'll find him something to put on."

"Where are you fellows taking me to?" suddenly demanded Chance.

"We ought to be taking you to jail," growled Billy.

"We're running outside on important business, Avery," explained Dan, gravely. "You'll have to go along. We can't stop to put you ashore at Riverdale now."

Avery evidently knew who it was who had rescued him. He never uttered a word in gratitude; but when Dan found him some of his own clothes that he had in the cabin lockers, the fellow stripped, put them on, and was evidently glad of the chance.

As soon as he could, Dan got back to the engine and the Red Arrow increased her speed. Billy aimed her directly for the light on the end of the breakwater.

"Say, Speedwell, you can put me off at Barnegat," growled Avery, coming out of the cabin, after spreading out his saturated clothing to dry.

"What do you think this is—a pleasure boat run for your benefit, Chance?" snarled Billy, who overheard the remark.

"Where are you going?"

"To Wild Man's Island. We'll bring you back as soon as we can, but we've got an errand there and can't stop."

A little later Dan stepped up beside Billy and whispered:

"I don't know what Mr. Craig will say to our bringing him out there. But what can we do?"

"Land him along this other shore," said Billy.

"That wouldn't be right. There's no railroad, and mighty few houses. He might get lost in the woods. It wouldn't be fair."

"Fair!" sputtered Billy. "Was he ever fair to us?"

"What's that got to do with it?"

"Aw, shucks!" growled the younger lad. "You make me tired sometimes, Dan."

Billy gave his attention to the steering wheel while Dan went back to the engine. Their speed increased soon, for there were no lanterns of craft ahead of them, save the riding lights of the boats at anchor behind the breakwater.

The light Billy had been laying his course by was now a big, brilliant glow against the hurrying clouds. The lighthouse stood upon the very end of the breakwater, and the Red Arrow passed it and breasted the rollers coming in from the broad Atlantic at a few minutes past ten o'clock.

The boys could not see the wireless station as they approached Wild Man's Island; yet when they were quite near, and the bulk of the island had broken the stiff breeze for them, and the launch was shooting through the more quiet water, they were startled by several sharp, snapping reports, and looking upward among the rocks, the blue flashes of the electric spark were visible to their eyes.

"He's repeating his wireless message to us, Dan," shouted Billy.

"I believe so. It is eleven o'clock and after. He'll think we are never coming."

"We ought to have a wireless outfit on the Red Arrow," said Billy.

"She wouldn't carry such a heavy top-hamper," objected Dan.

When the wireless sparks began snapping, Chance Avery sat up and began to pay more attention to what was going on.

"There's somebody on that place," he said to Dan.

"I reckon so."

"That man Craig, eh?"

"I don't know as it's any of your business, but Mr. Craig is there," responded Dan.

"Huh! he's a chump," said Chance.

"That's a matter of opinion, I reckon," Dan said, some curiosity aroused in his mind now, because of Chance Avery's speech. "How is he a chump?"

"Oh, he has been having some kind of a machine made at the shops. Frank was telling me about it. And they can't seem to suit him in the pattern department. Robert Darringford is away and you can bet that Frank isn't taking any ‘slack' from a fellow like this Craig. So, when Craig objected to the work when the job was done, Frank told him he could take it elsewhere."

"I reckon so. That sounds just like your brother," grunted Dan. "Some day Mr. Darringford will put his superintendent out of the Darringford shops by the slack of his trousers—and I've a full length photo in my mind of his doing it mighty soon."

"You make me laugh!" returned Avery. "Why, the Darringfords couldn't get along without Frank."

"I know he acts so, and you think so," said Dan. "But you'll both wake up some day."

This he said as he shut off the engine and ran forward to carry a line ashore. Billy put the nose of the launch into a familiar dock between two ledges. The Speedwells had become past-masters in the art of landing here, mooring the launch with two lines, and leaving her safely bobbing on the tide, unable to even scratch her varnished sides against the rugged rocks.

When the mooring was accomplished Billy joined Dan on shore. He walked up to his brother and whispered:

"Now what the dickens are we to do with that fellow? If we leave him here, free, he'll get to snooping about and perhaps meddle with some of Mr. Craig's affairs. Why, Dan, you'd no business to ever drag him out of the river!"


VII. — THE SUBMARINE BOAT

OF course, Billy Speedwell did not exactly mean this; but he was inclined to exaggerate his statements when he was excited. And the fact that he and Dan had brought to Wild Man's Island a fellow like Chance Avery, when Mr. Asa Craig was particularly anxious to keep the general public away from the place, now loomed big in Billy's mind.

He would not have had Dan leave Chance to drown; but the fellow's presence on the Red Arrow was awkward, to say the least.

"What'll we do?" asked Billy. "Crickey! there never was a time, or a place, that Chance Avery wasn't a botheration."

"We can lock him in the cabin, and I'll disconnect the machinery so that, even should he escape, he will be unable to run away with the launch," said Dan. "We'll try to make it impossible this time for him to make us trouble," and he leaped aboard the Red Arrow again.

He went directly to the motor and removed a certain part that he could easily slip in his pocket. He knew for certain that the launch could not be started until he had returned that part to its place.

Then he turned his attention to Chance Avery, who had, all this time, sat grumpily on the deck without apparently paying any attention to the Speedwells.

"Avery," said Dan, firmly, "we are going to ask you to turn in. You can take either of the berths—you'll find them comfortable. We'll wake you in time to put on your own clothes and go ashore. This is the best we can do for you."

"What are you fellows going up to?" demanded Chance.

"We are going ashore."

"And leave me here; eh?"

"That is our intention," said Dan Speedwell. "I reckon you're not afraid of the dark; are you?" and he laughed.

"It doesn't matter what I am afraid of," sneered Chance Avery; "I'm not going to bed——"

"Why, you may take your choice about that," Dan interrupted, still with cheerfulness. "There are some books and papers below. You can amuse yourself with them if you prefer."

"And suppose I don't care to do either?" snarled Chance.

"That makes no difference to us. You can sleep or remain awake. But into that cabin you are going," declared Speedwell, confidently.

"I'll do nothing of the kind!" yelled Chance, getting wildly excited. "How do I know what you are going to do, now that you have brought me clear out here?"

"He's afraid!" scoffed Billy, from the landing.

"I'll punch your head for you, Billy Speedwell!" exclaimed the angry Chance. "You fellows are carrying things too far——"

"We did when we carried you clear out here to Wild Man's Island, I admit," cried Billy. "We'd ought to have dropped you back into the river."

Now, this wasn't nice of Billy Speedwell, but he was grouchy himself—and Chance Avery's presence here was, as Billy had pointed out, very unfortunate.

Whether Chance had any intention of leaping ashore, and trying to chastise the younger boy, or not, Dan stopped him. His hand was on Avery's shoulder, and he switched that young man suddenly toward the cabin door.

"Down you go, Avery!" he declared. "I am determined to shut you into that cabin."

Chance whirled on him and struck out with his fist; but Dan was in no mood now for a game of fisticuffs. He caught Chance by the wrist and stopped the blow.

"And I haven't time to fight you," Dan Speedwell declared. "Into that cabin you go—and you'll stay there till I choose to let you out—or, so I think."

"I won't!" yelled the fellow, struggling to hold his position on the deck.

"You will!" repeated Dan, and suddenly whirling him about, he seized Chance by the collar of his shirt and the waistband of his trousers. Thus holding him, Dan ran him to the cabin door, which was open.

"In you go, my hearty!" ejaculated the elder Speedwell, with a last vigorous shove.

Chance, roaring in anger, fell forward on his hands and knees and Dan delivered a final push with his foot and so got him into the cabin. He instantly banged too the door, snapped the lock, and so held Chance prisoner.

Billy held a pocket electric torch in his hand. He led the way quickly along the ledge to and past the head of the natural dock in which the launch lay moored. Within a few yards they turned sharply from the sea, dodged under an overhanging boulder, and entered a cavity in the sheer wall of the cliff which here rose so high that, in the darkness, one could not gain any idea of its magnitude.

"Is this the place?" whispered Billy in Dan's ear.

There was no reason for silence, but the night was so dark, and the cave so rude and wild, that the lad could not fail to be impressed by both circumstances and surroundings.

Dan was feeling along the wall at one side. He said:

"I'm sure this is the entrance; but shoot your light this way—Ah! never mind; here is the wire."

Billy, however, focused the electric lamp on the spot and revealed in its white ray an insulated wire which ran out of a narrow crack in the rock and up overhead, where it disappeared in the darkness.

"Now, we'll find the button," muttered Dan.

He crept along a bit farther and finally, stooping down, poked his finger into the same crack just where the wall of rock met the floor, and pushed an electric button.

Billy was waving the ray of light around the cavern, which was some ten yards square. It looked like a water-worn cave, and that was all.

"Nobody would ever suspect that this was the ante-room of Aladdin's Palace," he chuckled "Would they, Dan?"

"Or, where the Admiral says the Dardanelle emeralds are buried," and Dan laughed.

"Never you mind. I'm going to have a look at that place where the sloop is wrecked with the emeralds in her cabin," declared Billy.

"Suppose that story is true, Billy?" asked his brother, with some interest.

"Of course it's true!" declared the enthusiastic younger lad. "The Admiral didn't have any reason for telling me a falsehood."

"Excepting that some of these old sailors are prone to tell whoppers," chuckled Dan. "Especially to land-lubbers, you know."

"No. He wasn't fooling me. I believe the Fannie Hendricks is buried under the Slide, just as he says, and that the emeralds are in her cabin."

"Boat and all are flattened out like a pancake at the bottom of the cove, if all that avalanche of dirt and rocks fell on her," said Dan.

"We might dig down," said Billy, thoughtfully.

"No. What struck me when you spoke of these caves," said Dan, quietly, "was the fact that there are many subterranean passages in those cliffs over there, just as there are on this island. The sandstone is honey-combed with them. Suppose we could reach that wreck through the caverns in the cliffs?"

"Glory!" yelled Billy. "That would be great."

At the moment there was a sudden grating, jarring noise. The seamed wall of rock before them yawned—a section of what had appeared to be solid stone, swung back on a pivot—and in the aperture appeared the figure of a man.

"Well, boys, have you come at last?" demanded a pleasant voice, and the man they had come to see stepped forth and shook them each by the hand.

"We came as quickly as circumstances would allow, Mr. Craig," explained Dan; "but you became impatient, and sent a second message; did you?"

"No. Not to you. That was to Fred Gedney, my cousin. I need him—or shall need him shortly—as well as you boys."

"Then the wonderful boat is ready to launch!" cried Billy, in delight.

"Come in," said Mr. Craig, smiling. "You shall judge for yourself."

The boys, who had been into this tunnel (partly of natural formation and partly the result of much work and ingenuity on their friend's part) pushed through the opening after Mr. Craig. That gentleman stopped to push the lever that controlled the massive door. It slid into place creakingly; but without a knowledge of the way to open it a burglar would have had a hard time making an entrance into that cave.

Mr. Craig then found a button somewhere, pressed it, and the tunnel for some yards ahead was flooded with light. He had hung incandescents from the roof of rock and, as he had a big dynamo running in his workshop, he easily supplied the necessary light.

"We came as soon as we could, Mr. Craig," Dan repeated, as they walked on with the inventor.

"That's all right," returned Mr. Craig. "I have some important work for you and Billy to do. There are certain drawings I wish taken to Compton, a pattern made, and the pattern brought back to me in the quickest time possible. You boys can do it—that is, you can get to Compton—by to-morrow noon, eh?"

"Why," said Dan, slowly, "sooner than that."

"Maybe," returned Mr. Craig. "I'd like to have the pattern to-morrow, but I know that is impossible. Ah, here we are, Billy. Now take a look at the Monster of the Deep."

As he spoke the three came suddenly out of the narrow passage into a great cavern. It was so huge a subterranean apartment, and its roof was so high, that the clusters of electric lights, under their big reflectors, looked like mere sparks in the distance. The trio had come out of the tunnel upon what seemed to be a gallery of rock that ran completely around the great amphitheater.

It was not the monstrous cavern, nor the electric lighted gallery, nor yet the fact that a good part of the floor of the cavern seemed to be covered with a lake of water, that was the surprising thing to view. On the edge of the water were the remains of a vast scaffolding, and wooden "ways"; while floating in the water itself, with perhaps six feet or more of its whaleback deck showing, was a long object that seemed more like a water-logged hull than anything else—and a hull seemingly made of plates of silver.

This shining object, with a low conning tower built of thick glass, and two hatches at present open and giving entrance to the interior of the hull, was the object to which Mr. Craig had called Billy's attention.

This was the submarine boat; a masterful invention which, its builder believed, would, in time, revolutionize naval warfare. It was upon this invention that Mr. Craig had spent all his fortune and many years of his life. And now, for the first time, the Speedwell boys saw the craft afloat and, to all appearances, ready for sea.


VIII. — QUICK WORK

"SHE'S launched!" gasped Billy Speedwell, gazing with wondering eyes upon the marvelous craft which floated so buoyantly upon the still pool in the vast cavern of Wild Man's Island.

"And you got her off the ways all by yourself, Mr. Craig?" inquired Dan, who had been quite as interested in the building of the submarine marvel as was his brother.

"She launched herself when I knocked the wedges out from under her," said Mr. Craig.

"But, she is done!" cried Billy. "The wonderful thing is accomplished."

"Not quite. Otherwise I should not have sent for you boys in such a hurry. The trial trip of the submarine has to be deferred for a time."

"But, Mr. Craig!" exclaimed Dan, "however will you get her out of this cavern? Shut in on all sides by walls of rock——"

"I know!" ejaculated Billy. "Mr. Gedney told us that you would blow out one of the walls."

"Exactly," said Mr. Craig. "That is his work. I am sending for him now to do his part. And when the wall is blown out the submarine will be free to leave this place where I have built her."

He turned quickly and ran down to a little shack built beside the "yard" in which the submarine had been constructed. Out of this he came quickly with a leather case—in fact, what is known as a "music roll." The leather case he gave into Dan's hand.

"There are my drawings and instructions to the man whom I wish to make me the part I need. I have already lost valuable time by experimenting with the Darringford people. Some day that fresh superintendent they have in those shops will throw down a big order for his proprietors and then they will wake up to the fact that his being in control is a detriment to the shops."

"It isn't Mr. Robert's fault," Dan hastened to say, for the Speedwells had reason to know that the younger Darringford was their friend. "The old gentleman considers Mr. Francis Avery a really wonderful man. That is why he remains superintendent of the shops. He has wormed his way into his employer's confidence."

"Just as Chance does," growled Billy. "And when he wormed his way into the river to-night, we ought to have left him there."

"How's that?" demanded Mr. Craig.

"I wanted to tell you about it," said Dan, quickly. "We were obliged to bring Chance Avery to the island with us."

"What, Dan! You brought somebody here?" cried Mr. Craig.

"But he's locked in the cabin of the Red Arrow," Billy hastened to put in. He then went on to tell of their adventure on the way to the island, and how Chance had been rescued.

"You could do no differently, boys, as I can see," said Mr. Craig. "But as time goes on I feel more and more nervous about the submarine. If my plans should be stolen, or if certain mechanics should examine my work, my chance to sell my invention to the United States Government would be small indeed.

"Now, I want you both to hasten away on this errand. There is the address of the old fellow in Compton who has made patterns for me before, and will do it again, under stress. I have explained in my letter to him what I want Get there as soon as you can; take your auto and run to Compton, and wait for the thing to be done. I have promised in a week's time an exhibition of what the submarine can do. I have the Navy Department interested. To you boys I will confess the secret: an assistant secretary of the Navy will be at a certain place a week from to-morrow, ready to have the submarine shown him and to follow her trial trip in the torpedo boat Yankee Doodle."

"Oh, Mr. Craig!" exclaimed the impetuous Billy. "I'd give a dollar to go on that trip."

The inventor laughed and shook his head.

"What do you suppose your mother would say if I should take you on my submarine down under the sea? Perhaps—sometime—when you are grown—Well, that's not the point we are discussing. Can you two boys do that errand for me?"

"Certainly we can, Mr. Craig," declared Dan, quickly.

"Of course. I can always depend upon you. And you will get back by day after to-morrow? It is almost midnight now, you know."

"We will do better than that—if your man at Compton will do the work at once."

"It will not take him more than four or five hours," declared the inventor.

"Then we will be back to-morrow night," rejoined Dan.

"Huh!" cried Billy. "We'll have to travel in the Red Arrow quicker than we did to-night, then."

Dan grinned and kept his own counsel. All he said was:

"We won't have to stop to save a chap from drowning, this time. Now, let's be off."

With some final instructions, and admonitions to make the best time possible, Mr. Craig parted with them at the mouth of the cavern. The Speedwells almost ran back to the spot where they had left the Red Arrow. It was safe and there was a lamp burning in the cabin.

Dan peered into the window as they leaped aboard.

"He's taking captivity philosophically," he said to Billy.

"How's that?"

"He's reading. Now we'll get right under way. No loafing, Billy-boy."

"You've promised a whole lot for us to perform, Dan," complained Billy. "We are fifty-eight miles from John Bromley's dock if we're a foot. Then we will not be half the distance to Compton. There'll be delays—there's bound to be."

"Hold your horses. I have a plan. We won't stop to discuss it now, but you attend to the engine and let me have the wheel."

Dan had already brought the hawsers in board. Billy gave the fly wheel a few turns, and the motor throbbed, echoing against the rocks like a series of musket discharges. The Red Arrow backed out of the inlet, turned on her heel under Dan's skilful ministrations, and then darted away from Wild Man's Island.

But in less than a minute Billy was yelling at the top of his voice:

"Hi! how are you going, Dan? You're hearing away from the breakwater."

"Never you mind, son," returned Dan, easily.

"Your old Uncle Dudley knows what he's about."

"I'm not sure that Uncle Dudley does," protested Billy. "Why, you're aiming for Rickett's."

"That's just about the spot I'm bearing off for," admitted Dan, for Billy had now come to stand beside the wheel.

"How will that help us make time going home? Surely, you don't mean to go by train?"

"There isn't any train at this time of night," returned Dan.

"That's so," declared his puzzled brother. "Then why are you aiming for that light?"

"Because I am going to land her in the cove behind the wireless station."

"But, Dannie——"

"Wait. We'll send Chance home by train—in the morning."

"Huh! what's he got to do with it?" demanded Billy. "I wouldn't trouble my head about him."

"Perhaps not. But we must take him into consideration a bit."

"Well?" growled Billy, still puzzled and ruffled because Dan was guying him a bit.

"Now, boy, we're out for quick work, aren't we?"

"That was our aim when we left the island," admitted Billy.

"More than that, we're due to make a record," added Dan, with continued cheerfulness.

"Maybe; but I'm not so sure of it now," said Billy, doubtfully.

"Don't trust your Uncle Dudley—eh?" jeered Dan.

"By crickey, Dan! I don't see what you're going to do," cried the younger lad. "It seems to me as though we were going a long way out of our course——"

"How far is it—approximately—by sea to Riverdale—to our house?"

"Near sixty miles."

"Yes. And about the same by land?"

"It is," agreed Billy.

"How fast can the Red Arrow travel?" demanded Dan.

"She might make seventeen or eighteen knots to-night. Wouldn't dare do more."

"Again correct!" exclaimed Dan. "And our wheels are aboard."

"Our motorcycles!" gasped Billy, light suddenly flooding in on his mind.

"Now you're waking up. What time can we make over the roads between Rickett's Point and Riverdale?"

"By crickey!" ejaculated the suddenly excited Billy, "over some stretches of road I wouldn't be afraid to do a flat sixty miles an hour."

"Then——"

"I see, Dannie! I see!" interrupted Billy. "We can beat the launch all to flinders on our motorcycles."

"That's the ticket. If we have good luck we'll be a-straddle of them in an hour. It's quick work we're after, and close connections. We want to help Mr. Craig if we can. I gather that much depends upon our, errand and our quick return with the article he wants. I'm going to cut corners, boy—I'm going to cut corners."


IX. — CUTTING CORNERS

BILLY SPEEDWELL agreed instantly to his brother's plan. He could see the advisability of getting ashore as soon as possible and taking to the motorcycles if they wished to make good time and please Mr. Craig.

The Red Arrow was a swift little craft; but she could not, of course, travel as fast by water as they could drive their motorcycles over the roads between Rickett's Light and Riverdale.

Before the launch passed the light and the wireless station, and ran into the cove, Dan cried:

"Shut her off!" Billy obeyed. "Now open that cabin and tell Avery he's free to land with us—in fact, he must land. I am going to put a man aboard the launch as boatkeeper while we are gone."

There was a gasoline torch flaming on the boat landing. The boys had been there before in the launch and they knew the proprietor of the place—a man named MacCormick. He had two sons.

When Dan and Billy, with the grumpy Chance Avery in tow, stepped ashore, one of these MacCormick boys came yawning out of the boathouse.

"Hullo, Mac!" said Dan Speedwell. "We've a job for you."

"Give it to us," said the red-headed Irish lad. "I see the both of ye are well lookin'. But what's your haste?"

Billy was hoisting one of the motorcycles ashore, and he said:

"We're in a hurry, Mac. There's a hard run before us, and Dan says he's going to cut corners," and he laughed.

"And this other fellow?" queried the boatman's son.

"We don't want him around the launch," said Dan, bluntly. "There's a dollar in it for you if you sleep aboard and watch her till we get back, Mac."

"And not let this laddy-buck aboard, eh?" queried MacCormick, eyeing the scowling Chance unfavorably.

"Surest thing you know," said Billy. "Here's your machine Dannie."

He hoisted out Dan's motor. Both Speedwells started up the landing trundling their cycles.

"You know where the railroad station is, Chance," said Dan, briefly. "There is a train going up to Riverdale somewhere about six o'clock. You can take that."

He and Billy hurried on to the highway which ran not far from the boat landing. It was already nearly one o'clock. Both boys were eager to be astride their motorcycles.

In a very few seconds the explosions of their engines startled the echoes along the shore of the cove. Dan and Billy kept side by side and bent over the handlebars of their steeds of steel. The music roll, with Mr. Craig's plans in it, was slung around Dan's neck. They crossed the railroad at Rickett's Station in short order; but it would be a long walk for Chance Avery to this point. On and on the boys sped over the smooth bits of macadam, lowering the pace for rough stretches of road, and for corners; and finally the lights of Riverdale lit up the clouded heavens just ahead. They climbed the last hill and came into the lower end of town.

At a few moments past three they ran into the yard of their homestead and shut off their engines. Their father and the hired man were busy with the chores.

"You'll have to use the old wagons this morning, father," Dan said. "We have to go to Compton for Mr. Craig and we will have to use the car."

"All right. The milk isn't in the rack yet. The wagon body can easily be lifted off the trucks," returned Mr. Speedwell, cheerfully.

"But why can't you keep on with the motorcycles if you are in so great a hurry, Dan?"

"The article we have to bring back is too heavy for transportation on our wheels," returned the lad.

Mrs. Speedwell was already up, and she came to the door and called the boys in to breakfast.

Mr. Speedwell soon ran the truck of the motor car out of the barn.

"Is she all right, father?" asked Dan, with anxiety.

"She is, my boy," returned the farmer. "Now be off with you. When will you come home?"

"Can't tell you that," said Dan, as he cranked up. "We shall not come this way on our run back to Rickett's Point. There is a nearer way by Clifton and the high trestle."

"Be careful on that bridge, Dan," warned his father in a low voice. "I understand that she is shaky."

"That's only an idle report I think," responded his oldest son as the engine began to speak. Billy had already hopped in. Dan slid to the steering wheel and cried:

"All ready?"

"Let her go," said Billy, eagerly. "There are no strings on us that I see."

Dan let in his clutch and pressed his foot upon the accelerator pedal. The automobile responded with a leap that carried her out of the yard and she tore up the road at top speed.

It was then four o'clock. They were only about half way to their destination, for Compton was sixty miles further across the State.


X. — RACING AGAINST TIME

IT was impossible for the Speedwell boys to make the time between Riverdale and Compton in their car that they had made on their motorcycles from the landing behind Rickett's Light to their own home. But, as Dan had explained to his father, they could not carry on their wheels the article Mr. Craig wished made at the pattern shop in Compton.

They drew in to Compton at about seven o'clock and Mr. Craig had expected them to arrive at their destination by noon; but they had gained five hours over that time, and when they found the pattern shop of the old German to whom the inventor had sent them, they likewise found him just arrived at his door, and signing the book of a telegraph boy who had met him there with the message.

"Vell! vell! was iss?" grumbled the old fellow, wiping a pair of huge spectacles preparatory to reading the telegram.

Billy, impetuous as usual, leaped from the car the moment it stopped and ran to the machinist.

"You are Mr. Troutman, aren't you?" he demanded.

"Yah—yah!" grunted the German, nodding vigorously. "It is my name."

"Well, we've got a job for you—a rush order," cried Billy, turning to beckon Dan from his seat.

"Veil, it looks like this vas mein ‘rush order'—yes?" returned the old man, shaking the telegram that he had not yet read, in his hand. "I vill do noddings to-day, I guess."

"Oh, Mr. Troutman!" exclaimed Billy. "This is very important. We come from Mr. Asa Craig. You know him?"

"Yah—yah! I know him," replied the man, impatiently, setting the glasses astride his nose. "But I cannot bodder mit him now."

"Why not?" asked Dan, earnestly, coming likewise to the door. "This is a very important matter he has sent us on."

"Vot iss imbordant like dot?" cried the old man, in some heat, shaking the telegram in the air. "I got von from de old country when mein brudder, he died. Undt I got me anudder telegram ven mein wife's sister died in Jacobsburg, Pennsylvania yet. Den, when mein parn burn oop undt de horse, he vas dead, too, undt I wrote by de fire insurance beoples about idt, idt is anudder telegram vot gomes tellin' me mein insurance run oudt de day pefore de fire yet!"

The old fellow continued to shake the envelope and his own head in commiseration of his bad luck.

"My gracious!" groaned Billy, "do open the telegram, Mr. Troutman. Let's know the worst."

"Or the best," suggested Dan.

The old man opened the envelope at last and pulled out the message. He read it once with a very glum face. Then he read it twice, and scratched his head, tipping his old wool cap in a ludicrous way over one eye.

The boys had waited with something like dread, too, up to this point. If the old man had received bad news they were prepared to feel sorry for him; but the expression on his face gradually changing, Billy finally burst into a shout of laughter.

"Hi, you boy!" growled Mr. Troutman. "You think this iss funny—no?"

"I think it's funny—yes!" gasped Billy. "Somebody's left you money in their will."

"Nothing of the kind, nothing of the kind," declared the German, sternly. "I don't know vedder you iss de poys dot vos sent here by mein goot friendt, Herr Craig, or not. Vas iss your names?"

"I am Dan Speedwell, and this is Billy Speedwell, my brother," explained the older lad, confidently. "Have you received a message from Mr. Craig?"

"Dis is idt," said the German, handing forth the telegram. "It says it iss repeated at Rickett's Point, ‘from wireless.' Vas iss dot ‘wireless', yes?"

"Mr. Craig is on Wild Man's Island," explained Dan. "We have just come from there—by boat and motor car. He tells you we are coming."

"Sure! here iss his name signed to it," declared the old man, confidently.

"And he tells you to expect the Speedwell boys with some drawings?"

"Yah. Ve vill come the shop in. Meppe I do this t'ing for Herr Craig right away."

"I hope so!" murmured Dan, as the boys followed him into his queer little shop.

Troutman worked all by himself. He had no assistant. Although he was so simple minded, he evidently was a good workman. Otherwise Mr. Craig would not have trusted him so implicitly.

The boys stayed long enough to see the old man study out the drawings and read the instructions; then he turned on his power and began to work. Dan and Billy went out to buy them something to eat, for like healthy boys they were hungry again. They had to replenish their stock of gasoline, too, and after doing these errands they gave the engine another look over. There was a run of more than a hundred and twenty miles before them on the return journey to Rickett's, and as far as it lay in their power they headed off the possibility of accident.

They kept their eye on the old German, too. Few people came to his shop, and it was likely that that was another reason why Mr. Craig had chosen Troutman to do this piece of special work.

The old man kept steadily at the job and at a few minutes past eleven the boys heard his power shut off. The whir of machinery ceased, and they ventured into the shop.

"Veil!" growled Mr. Troutman. "Dot iss a day's vork done in von forenoon—ain't idt? You tell Herr Craig dot I don't like such chobs."

"And is it ready for us?" cried Billy.

"Idt iss done. I haf done mein best," said the solemn old German. "No man can do more—yes?"

Dan and Billy wrapped the odd shaped apparatus in heavy paper and carried it out to the car. Five minutes after Mr. Troutman told them the work was done, the Speedwell boys had started their auto and were traveling out of town at as high a rate of speed as they dared.


XI. — A NARROW ESCAPE

A trip over the hard, well-made country roads by broad day was much different from the run the Speedwell boys had made in the early morning, first on their motorcycles from Rickett's Point to Riverdale, and then in the car to Compton.

"Crickey!" ejaculated Billy, as they sped along the broad highway, "we can see what we're doing now, Dan."

There was less likelihood of peril to themselves or to other people by daylight, that was sure; but Dan, manipulating the mechanism with skill, got the car to high speed between towns, and sometimes held her there so that, in rounding a curve or corner, the auto took it on two wheels only.

Soon they branched off, leaving Clifton on their right hand, and went up the steep hill leading to the trestle bridge behind Rocky Cove. There was a deep gulf here between the hill on which Clifton was built and the rugged promontory overlooking the landlocked bay known as Rocky Cove.

Across this gulf, and winding for a distance along the steep shoulder of the more seaward eminence, was a plank bridge, set up on a high trestle. The bridge had been built originally by a private corporation that had tried to make of Rocky Cove a summer resort. The proposition had failed—had died in its infancy, in fact. The county had never assumed responsibility for the road approaching Rocky Cove from this direction, nor for the trestle itself; but the way was a short cut to Rickett's and the Light and was often used.

Dan remembered that report had it the trestle was shaky. And his father had warned him regarding it that very morning; but two weeks previous the boys had been over the old plank bridge and had seen nothing wrong with it. However, as they made the approach to the trestle that straddled the deep gully, Dan slowed down.

"Some day somebody is going to get caught here," he said to Billy, peering ahead sharply. "This old thing will go down—a slice of the hill and all, perhaps—just as the Slide went, away back in 1876."

"I'd hate to be buried under it as the Admiral says that sloop and her sailing master are buried," responded Billy.

The heavy car trundled out upon the bridge. It seemed to Dan as though the structure really did shake more than usual.

He was tempted to slow down, and his hand sought the clutch.

Suddenly there was a loud snap, a thunder of falling timbers, and the whole trestle sagged. Dan and Billy instantly realized what had happened. The sleepers over which they had passed had broken away from the bank. The end of the bridge nearest Clifton had given way.

"She's going!" yelled Billy Speedwell, half rising in his seat.

They were at least forty feet from the solid ground at this spot. If the trestle fell with the car on it the boys would certainly be dashed to their death among the rocks below.

But Dan recovered his presence of mind in a flash. He felt the trestle sagging, and almost on the instant his foot pressed on the accelerator.

Like a bolt from the bow the car shot ahead. The end of the shaky old bridge went thundering down into the chasm. Its weight tore loose the next section; but the motor car had passed over it in season.

On and on she sped, over the creaking, shaking structure, and in a very few seconds the danger was passed; but the boys looked back from the far end of the trestle to see a most remarkable phenomenon enacted behind them.

The entire side of the hill had slipped. Trees, rocks, stretches of greensward, earth and rock together, had slid downward into the gulf—was still sliding as the boys halted the car.

"We just missed it, Billy," whispered the older lad. "A little more and Mr. Craig would not have seen his pattern that he is so very anxious for."

"Crickey! I never thought of his old pattern," grunted Billy. "We came as near as can be to getting in the same fix as the sloop the Admiral told me about. Let's get out of here, Dannie. Maybe some more of the hill will fall."

Whether there was danger or not in their lingering in this spot, the necessity for their continuing on their way at a good rate of speed was impressed upon both their minds.

They saw persons running toward the scene of the accident; but they did not stop to discuss the occurrence. Dan let the car out again and they ran down and skirted the cove, where they could get a clear view of the sloping bank known as the Slide. The new avalanche of earth had been upon the shoreward side of the same cliffs—directly behind the old avalanche.

As the car whirled along the farther shore of Rocky Cove Billy looked back and saw the place on the hillside, where the recent slide had uncovered the rocks.

"Gee! that's a barren looking place now," he shouted to Dan. "And there's a hole there—looks like a cave."

"The cliffs are full of them—we know that," replied Dan.

"Suppose a fellow could find a passage down through the cliff and under the old slide that buried the Fannie Hendricks! Wouldn't that be great?"

"It would have to lead under water, too," chuckled Dan.

"Well, we could get into diving suits," said Billy, stoutly.

Meanwhile the motor car was speeding down the rather sandy road toward the light, and the boat landing behind it. This was really the worst five miles of highway they had had to travel since leaving Compton; but the car did well. She spurned the sand beneath her tires and pounded on down to MacCormick's landing.

There lay the Red Arrow, safe and trim! Mike MacCormick—he of the red head and broad smile—lay on her deck like a watchdog, and welcomed the Speedwells cordially when they stopped the car.

"We'll change with you, Mac," declared Dan, as he and Billy hurried aboard the launch with the article they had brought for Mr. Craig. "You watch the machine till we get back from the island, will you?"

"Sure thing," returned the young Irishman. "Was you looking for anybody to be disturbing of the automobile? That lad ye brought ashore here, for instance?"

"Didn't he go away?" asked Dan, quickly.

"Oh, yes. But in the cabin yonder is a screw driver he must have borrowed out of your toolkit, Master Dan. And I see he's had one of the cabin lights out. You had him locked into the cabin, I take it, for he tried the screw driver on the lock of the door, too."

"I told you, Dan!" cried Billy. "I bet he had that light out while we were over there talking with Mr. Craig."

"Suppose he did?" growled Dan, but somewhat disgusted with his own short-sightedness. "He couldn't have found his way to Mr. Craig's workshop."

Nevertheless, Dan warned MacCormick to keep a sharp eye on the automobile, and after he and Billy got aboard the launch and started her away from the landing, the older Speedwell said:

"He must have taken that screw driver when I wasn't looking. He expected us to imprison him in the cabin. That Chance Avery is certainly a sharp fellow."

"And he got out through the window and spied on us," said Billy, in disgust.

"That couldn't have done him much good," Dan returned, slowly.

"Why not?"

"It would be impossible for him to find his way into Mr. Craig's cavern. Even if he found the door, he could not enter."

"But suppose he spied on us?" cried Billy, eagerly.

"When?"

"While we were waiting for Mr. Craig to appear."

"What good would that do him, Billy?" demanded Dan, in wonder.

"He would have heard us talking about the emeralds," replied his brother. "He'd know as much about them as we do!"


XII. — THE CAVERN IN THE CLIFF

THEY got across to Wild Man's Island in the Red Arrow in short order, after leaving the auto at the landing behind Rickett's Light. It was hut mid-afternoon then, and Mr. Craig had no reason to expect them so soon. The boys landed on the apparently deserted isle and went through the same formula of summoning the inventor from his subterranean retreat.

He was delighted to see them so soon, and the part of his machinery the old German at Compton had made for him proved to be exactly right.

"You have done my errand more promptly than I could have hoped, boys," said Mr. Craig. "Things seem to be going on nicely just now, too. I have heard from Mr. Gedney; he will be here before the end of the week to aid me in blowing out the wall of my cave to release the submarine. Now I want to reward you for what you have done, boys——"

Here Dan broke in with some eagerness. He and Billy had already discussed a certain matter and the older Speedwell put it to the inventor bluntly:

"Mr. Craig, don't think Billy and I wish to be paid for doing this for you—for we don't. We can never thank you enough for giving us that beautiful power launch in the first place. But there's something you can do for us that will not cost you a cent, but will reward us (if you wish to call it that) far more satisfactorily than in any other way."

"My! my!" exclaimed the inventor, with his usual pleasant smile. "This must be something of moment when you are so earnest in it, Dan."

"It is, sir—of great moment to us," and the lad looked at his brother and both nodded seriously.

"Out with it!" laughed the gentleman. "If it is even to the half of my kingdom——"

"We want to see you burst out that wall and float the submarine into the sea," cried Billy, impatient because of Dan's slowness.

"Whew!"

"Yes, sir. We want to be here when the wall comes down," Dan said. "You have trusted us a whole lot, Mr. Craig, and we're deeply interested in your boat. Billy doesn't desire to go down in her any more than I do, I can assure you."

"Aren't you afraid to trust yourselves in such a contraption?" asked the inventor, smiling.

"You're not afraid yourself, sir."

"Well, you are plucky lads. But we'll talk about your going diving in her at some later date. Your parents, I fancy, might have something to say about it," Mr. Craig said. "Now, about coming over here the day Fred blows out the wall of the cavern—Well, that's another matter. I might want you on that day, anyway."

"Bully!" exclaimed Billy.

"We have got to put some heavy charges of nitro, or some equally dangerous explosive, into that wall. Some of the holes are already bored in the rock. The explosion may shake things up a bit, and I had been thinking that it would be a whole lot better for Fred and me to be aboard your launch at the moment when the charges are set off, than anywhere on the island itself."

"That's fine," declared Dan, in delight. "You'll surely let us know in season, sir? You see, we are out of school now and we can get down any day in the Red Arrow."

"Your car is over at MacCormick's," the inventor said, thoughtfully. "Wouldn't it be a good thing to leave the launch there for a few days? Fred can use it to get over here when he comes down. It will save me going after him in the turbine."

Mr. Craig had a wonderfully fast turbine launch which he used in going back and forth to and from the mainland.

"You fix it with the MacCormick boys. They will look out for your launch and I'll send you word when to run down to the landing and come over here. The Red Arrow is much more roomy and comfortable than the turbine, and we can cook a meal on her. You couldn't cook anything on the turbine any more than you could on an iceboat."

So it was arranged. Dan and Billy were perfectly delighted with the plan when they pushed off from the island once more and ran over to the landing. They were to see the grand transformation that was to tear down the cavern wall and release Mr. Craig's wonderful submarine craft from the hidden place where she had been built.

The Speedwell boys left their launch at the landing in the boatkeepers' care, and sped home in their automobile, arriving in good season for supper. They were much excited over the forthcoming activities on Wild Man's Island; but they had to keep quiet about them, for they were under promise to Mr. Craig never to mention his invention to any person.

There was one matter, however, that they could discuss to their hearts' content. At least, Billy could not keep his tongue still about it. That was the treasure of emeralds he believed was hidden under the great slide at Rocky Cove.

"You won't believe until you hear the old Admiral tell about it," he said to the doubting Dan. "Come on! Let's go down and see the old fellow and ask him all about it."

"I can see very plainly that there will be no contentment in this family until we do that," laughed Dan. "I agree."

Therefore, it was the very next afternoon, after their work was all done, that the Speedwells got out the car once more and ran the distance to the little red house on the shell road in less than an hour. The Admiral was mending a mackerel seine, being in partnership with two other 'longshore men in a fishing boat. At Billy's request he told more of the story.

"Ye see, lads," he said, "after the rest of us escaped that avalanche over to Rocky Cove, leavin' poor Marksman in the cabin of the buried sloop, we scattered. Some of 'em had bigger fistfuls o' emeralds than me; but I reckon most of them frittered their gains away like sailor-men will.

"I was different. Tell ye the truth, what had happened to Marksman scared me—yes, sir! I was afraid to stay ashore, for fear something would happen to me, too! So I put them emeralds in a safe place and shipped again for Uncle Sam. I went right back in the old Yorktown, was exchanged when she was made a target, into one o' these steel pots, finished my 'listment, and left the navy then an' there for good and all.

"I tried sea-going a bit in the merchant marine; but that ain't what it used to be. The skippers is all college-bred, and there ain't no smart seamen. Besides, they thought I couldn't get around lively enough with my timber-toe. Ha! I had forgotten more about sailin' craft than most o' them merchant skippers ever l'arn.

"So I drifted about and finally cast anchor here. My share of the Dardanelle emeralds bought this snug outfit. It beats the Sailor's Snug Harbor all to flinders, don't it? I'm independent and am skipper, cabin boy and doctor—all by myself.

"Well, as I says, I settled here; I'd seen the spot a day or two arter we seen poor Marksman buried under the Slide. And bein' anchored so near to Rocky Cove I got to thinkin' more o' them emeralds. I 'lowed that mebbe a shaft might be sunk into the Slide," said the Admiral, waxing earnest, "and mebbe a coffer-dam builded down to the deck of the Fannie Hendricks. Of course, she'd be sunk fathoms deep by the weight of the rock and soil what fell upon her. That little inlet we moored in is filled completely over by the Slide.

"But, o' course, I couldn't undertake no such thing. 'Twould cost money—and a whole lot of it. So I'd taken a gentleman out fishin' a score o' times—Colonel Sudds he was——"

"Abram Sudds, of Riverdale!" exclaimed Dan.

"That's the gent," admitted the Admiral.

"Chance Avery's uncle," growled Billy. "If it hadn't been for Colonel Sudds, Chance and Mr. Frank Avery would never have come to Riverdale."

"I reckon you're right, Billy," agreed Dan.

"Howsomever," said the Admiral, "I told the Colonel about them emeralds. He thought 'twas too wonderful to be true. But I had figured out just where the Fannie lay and he agreed to sink a shaft down to her."

"And you did it!" gasped Billy, in vast disappointment.

"Well, we went at it," admitted the Admiral, rather gloomily. "He had some men dig where I said—and I knowed I was right as far as the latitude and longitude went," said the old sailor. "But nothin' ever come of it."

"How was that?"

"We dug down some forty feet and struck solid rock," declared the Admiral, gravely.

"Solid rock!" exclaimed Dan.

"You sunk the shaft in the wrong place!" cried Billy.

"No. I'm sure of the spot. He uncovered a ledge of rock twenty feet square and then Sudds got mad with me and give it up, and the hole was filled in."

"That certainly is mysterious," said Billy, shaking his head.

"No. I got it figgered out later," said the Admiral, with confidence. "Ye see, the dirt and rock is piled there seventy or eighty feet over sea-level. When the avalanche happened a monstrous boulder slid down with the rest of the rubbish and it rests right over the narrow basin where the Fannie Hendricks was moored. Perhaps it rests on the reefs on either side. D'ye see? That's what stopped us. It would take a ton of dynamite to blast through it," and the Admiral shook his head.

"No. I couldn't blame Colonel Sudds. Them emeralds is where nobody will touch them till Gabriel blows his trump—and mebbe not then!"

The old man was so earnest in his statement, however, than Dan was impressed as was Billy with his truthfulness. The boys spent the remainder of the afternoon with him; the Admiral insisted on making them an old-fashioned fish-chowder for supper, and the Speedwells did not start back home until the sunset gun was fired by its wooden-legged owner and the colors were run down for the night.

This was on Wednesday. When the boys arrived home they found an invitation from the Greenes to join an auto party to Rocky Cove the next day.

The newspapers had been full of the landslip in which the Speedwells had so nearly been caught while crossing the Clifton trestle. Of course, the fact that Dan and Billy had been on the spot at the time of the catastrophe was not known; but some of their young friends were desirous of seeing the place. It was, in fact, a good excuse for a picnic.

"You might as well call this week your vacation, boys," said Mr. Speedwell, laughing, when Dan and Billy preferred their request. "The doctor's daughter and Mr. Parker's girl were both over on their motorcycles this afternoon to make sure that you would take them in your car."

"But we can deliver the milk first," said Dan. "The note from Betty Greene says we are to meet at the square at half-past ten."

And this they did, running back in town to join the picnic party with the satisfied feeling of having their day's tasks well performed. Mildred Kent, the doctor's pretty daughter, and the vivacious "bronze-haired" Lettie Parker, were waiting for the Speedwells. They picked up Jim and Ruth Stetson to make up the party, and then ran to the Court House square where they found the Greenes' big automobile already in waiting. Beside Perry, Betty and Fisher Greene the big touring car held five other of their school friends. So it was a very nice party indeed that sped out along the country roads towards the ocean shore.

The Speedwells, knowing the way so perfectly, led the procession, and Dan set a pace that brought them to Clifton before one o'clock. They ran through the town and took the shore road around the foot of the promontory and across the Slide. Dan and Billy ran slowly here for a special purpose. They were looking for the spot where the Admiral had said Sudds' men dug the shaft.

There was still a mound of earth there. The hole had not been entirely filled in. Jim Stetson pointed this pile of dirt and rock out to the others.

"See that hole yonder?" he said. "Why, do you know, some fellers dug for treasure there years ago. Captain Kidd's millions, I s'pose. And you never could guess whose money paid for the work."

"Colonel Abram Sudds," suggested Dan, grinning.

"Ah! you've heard about it," said Stetson.

"That's who did it. Think of Colonel Sudds digging for pirate gold."

Dan and Billy glanced at each other again, but said nothing. They drove around the promontory, and up the other road to the end of the trestle that was still intact. Many tons of earth and rock had fallen the day Dan and Billy had run an automobile across the trestle for the last time.

The party stopped here and ate their lunch. It was perfectly safe to walk across the scarred hillside now; no more earth and rock could fall. And what attracted the young folks particularly was that gaping hole Billy had observed in the rock after the landslip—it was the mouth of one of those tunnels that were so common in these sandstone rocks.

"Let's explore it!" cried Lettie Parker, always ready for some madcap scheme. And when Mildred and Betty objected that they might get lost in the darkness, Miss Parker said: "What nonsense! Take the auto lamps. Of course we can't get lost. Come, Billy. I double-dare you."

"Oh, we'll all go, or none will go," said Betty Greene. "And I don't know but it would be fun. Is it dry in there?"

"Dry as a bone," declared Fisher, who had already been inside.

Therefore the party, with four lamps, ventured into the tunnel, which led downward into the rock. The slanting floor was quite steep in places and Dan (who led the way with one of the lamps, Mildred clinging timidly to the tail of his jacket) was confident that they would soon reach the sea level.

There were few obstructions in the wide passage, and very few cross tunnels. At least, it was an easy matter to follow the main passage without going astray. Suddenly Dan came to a wider opening. A draft of cool air blew upon his face. He shot the strong ray of his lamp into the opening, and he and Mildred stepped out upon a ledge, or gallery, which ran along the sidewall and not far under the roof of a vast cavern—a subterranean apartment as big as that on Wild Man's Island in which Mr. Craig had built his submarine boat.

Mildred exclaimed with delight as the lamplight flashed upon the stalactites pendant from the roof of the cavern. All the party hurried from the tunnel with murmurings of awe and delight and ranged themselves along the ledge where they could look about. The lights were reflected a thousand times in the pool of still water that filled the bottom of the cave, and everywhere hung the glistening stalactites.


XIII. — THE UNDERTOW

"ISN'T it the most beautiful place you ever saw?" cried the irrepressible Lettie Parker.

"The rays of lamplight broken by those stalactites give us all the colors of the rainbow," said Mildred Kent.

The surface of the calm pool was suddenly broken, and the light shone prismatically upon a fountain of drops that jetted into the air.

"A big fish jumped that time!" cried Dan, eagerly, as the splash of the finny creature echoed again and again from the subterranean lake.

"Then there must be an inlet from the ocean," Jim Stetson said.

"That's salt water all right," Fisher Greene said. "You may be sure."

A moment later both Dan and Mildred, still in advance of the others, uttered a simultaneous cry of surprise.

"A stairway!" ejaculated Mildred. "Did you ever see anything so strange in your life?"

"What wonderful things the water did in these rocks ages ago," Perry Greene remarked, coming forward. "I believe we can get down, though some of the steps are pretty high."

"Let's not try it, if we girls are going to have difficulty getting back again," Mildred said.

"We won't get you in any trouble," Dan said. "We can walk clear around the lake, I believe, if we get down to its edge."

They started to descend the rough-hewn steps and the girls found it much easier than it at first appeared. As they went down the air blew fresher and Billy cried:

"Let's put out the lights. There is a place across the pool where the sunlight is pouring in. There must be a hole in the cliff right there."

He was right. The party hastened along the edge of the water and reached a narrow opening through which they obtained a view of the sea and sky. Some loose boulders blocked this entrance to the huge cave, and it did not take the boys long to roll these out of the way so that they could all step out upon the rocky shore at the foot of the promontory, and not far above the highway over which they had ridden in their autos a couple hours before.

"We ought to have picnicked here!" cried Betty Greene.

"And none of us knew the tunnel was here beside the road," said her brother Fisher, scornfully. "This is a great old hide-out, Billy."

"Sure," agreed the younger Speedwell.

"Regular pirate's cave," said Jim Stetson.

"Mebbe there is some of Captain Kidd's money buried around here," Fisher said, seriously.

Before his sister and Lettie were through laughing at the youngster for saying that, Dan and Perry, who had gone back into the cavern, called to the others to come in. Dan had some bits of stick in his hand and the single lamp that was alight shone upon the black surface of the water where he threw in the bits of wood one after another.

"See them sucked into that eddy yonder," he said, eagerly. "See, down they go, one after the other. The tide's going out, isn't it?"

"Of course," said Billy.

"Then there's a submarine passage into this lake, just as Jim said. That big fish wouldn't have been here otherwise. And the current is sucked right down yonder. See those chips go!"

"Then I've got an idea," cried Lettie. "Billy, let us have that soda bottle—the one I brought lemonade in. I saw you put it in your pocket when we left the auto. Now, Dan, you surely have a pencil—and Perry always carries a notebook. We'll write a message, and all sign it, put it in the bottle, seal it, and throw it into the lake here."

"Good!" interrupted Fisher. "And we'll say we are shipwrecked on some island and if anybody finds it the yarn will be in the paper and folks will go hunting for the castaways."

"No we will not!" exclaimed Mildred, with a shudder. "We really were castaways last spring—at least Lettie and I were. We don't want anything to do with such a wildcat scheme."

"I didn't mean that at all," declared her friend. "We will send some message by the bottle—ask whoever finds it to send us word where it was picked up and the date. Then maybe we can learn something about the submarine opening—the hidden door of this cavern."

Perry supplied paper and a fountain pen. Mildred wrote a polite note asking whoever found the bottle to communicate with Dan and Billy Speedwell, at Riverdale, relating where and when the bottle was found.

"And offer them five dollars for the information," said Dan, suddenly. "I'll pay it."

"Oh—oh! five dollars!" gasped Lettie. "How extravagant!"

"What for, Speedwell?" asked Perry Greene, curiously.

"Well, I am willing to pay for just that information," Dan returned, smiling, but refusing to explain farther.

"It will probably be smashed against the rocks in being sucked down through that submarine passage," Perry said.

"Hold on!" cried Dan, before the bottle, now tightly sealed with its rubber flange and metal stopper. "I know a way to get over that."

They had written the message by lamplight in the cavern. Dan ran out of the place and leaped down the hillside, crossed the road, and ran out upon the sands where the ocean surf was rolling in with a soughing sound pleasant to hear. Cast above highwater mark was a good sized piece of grass-matting—the kind that comes around tea-chests. He secured this and ran back to his friends.

"I happened to notice this when we were looking out of that hole we made," Dan said. "Now, search your pockets, fellows, for some real strong cord. We'll wrap this bottle in the matting; it will thereby become an object more easily seen, it will float higher in the water, and it will save the bottle from being smashed the way Perry suggested."

So they finally entrusted the bottle in its mummy-looking wrappings to the black pool inside the cavern. The unseen, gripping current seized it almost instantly. The young folk followed along the edge of the lake for some distance until the floating bottle began to whirl round and round in the eddy. Suddenly it was sucked under and did not reappear.

The party rode home in the cool of the evening, after a most delightful day. Waiting for the Speedwell boys when they arrived at the farm was another telegram from Mr. Craig. It read:

"Meet the Red Arrow at MacCormick's at ten in the morning."


XIV. — THE 'QUAKE AT WILD MAN'S ISLAND

INTERESTED as the Speedwell boys had become in the lost treasure of Rocky Cove, the fact that they were to have an important part in the secret bringing forth of Mr. Craig's wonderful invention, excited them beyond measure. This wireless message, repeated from the station at Rickett's, set Dan and Billy on the qui vive. In due course they were at the dock.

"On time, as always, boys, I see," said Mr. Craig, as Dan and Billy lifted their cycles aboard and then shook hands with the gentleman. "And you are just in season, too. I have left Fred making the final arrangements. He was at work all day yesterday and all last night. He says that when we arrive at the island he will be ready for us."

"Aren't you afraid," asked Dan, as Billy took the wheel and he relieved the inventor at the stern of the launch, "that the explosion of so much nitro-glycerine will bring down the roof of the cavern upon the submarine?"

"Fred says not. He knows what he is about when it comes to explosives—no doubt of that. The only peril which menaces the submarine is the possible inrush of waves after the explosion. But we have anchored her securely, her hatches are battened down, and I do not believe she can be cast upon the rocks."

"If the rock-wall should be blown inward instead of outward, it would make a bad mess," Dan observed.

"No danger of that, I am sure. Yet I cannot help feeling some nervousness. No accident must happen to my boat now. In four days we must give an exhibition of her powers to the Assistant Secretary of the Navy. Until that trial trip comes off successfully I cannot feel sure that my boat is really perfected—and I have given fifteen years of my life to her!"

"Oh, it's bound to be successful," cried Dan, cheerfully.

The Red Arrow dashed up to the dock between the two great ledges, which the Speedwell boys always used because it was near the entrance to Mr. Craig's wonderful workshop. Mr. Gedney, the inventor's cousin, ran out along one of the ledges as the launch shot into the dock. He leaped aboard and Dan backed her instantly.

"You have set it off!" cried Mr. Craig, nervously.

"I touched the fuse when I saw you close in, Asa," returned the other, laughing. "How are you, boys?"

He spoke as calmly as though he had not just set burning the fuse of a blast that was expected to tear the side of the island to pieces. Mr. Craig took him to task for his recklessness as the Red Arrow moved at top speed away from the shore.

"Suppose something had happened to our engine? Suppose the launch had not reached the rock in safety?" he exclaimed.

"Then I should have leaped into the sea and swum for it," laughed Mr. Gedney. "For I don't mind telling you, A. C., that I wouldn't care to be on the island—not even at the far end of it—when that blast is fired."

"How long will it take?" asked Dan.

"Fifteen minutes at least."

"Hadn't we better run down to the end of the island so that we can signal to seaward and warn any vessel that may approach the island from that side?"

"I was in the lookout cave just before you appeared, and there was no sail near. The nearest craft is that launch yonder."

His words attracted the attention of the Speedwell boys to a black gasoline boat that was slipping through the sea at a good clip, but much nearer the mainland than the Red Arrow. She was considerably larger than the Speedwells' craft, too, and she flew the pennant of the Colasha Boat Club.

"Whose boat is that, Dan?" demanded Billy, from the wheel. "She's making for Rocky Cove; isn't she?"

"I judge she's going to run in there," returned Dan, giving the black craft another searching look. "Why, Billy I That's the Shoshone."

"The Shoshone? Colonel Abram Sudds' boat?" exclaimed Billy.

"Sure it is. It's too far away for me to read the name; but I am sure that is the boat."

"Colonel Sudds, eh?" growled Billy. "I wonder what he's going to Rocky Cove for now?"

Dan began to chuckle. He knew what was in Billy's mind. Colonel Sudds was the capitalist whom the Admiral had interested in the Dardanelle emeralds—the lost treasure of Rocky Cove.

At that moment Mr. Craig interposed: "You're far enough, Billy. Shut her off, Dan. Put her about so that she's bow on to the rock, Billy."

The Speedwells obeyed. The Red Arrow soon was courtesying to the swell very prettily, but under no headway. Mr. Craig pulled out his watch and looked at it nervously. The fifteen minutes must be up.

"Oh, don't be in a hurry, A. C.," chuckled Mr. Gedney. "She'll go off with a bang——"

His speech was halted suddenly. The atmosphere between the launch and the bald rock, which the moment before had been seemingly as clear as crystal, now vibrated and a tremor was felt through the launch.

The bare rock, some thirty feet above the sea which lapped its foot, opened clear across—yawned, indeed, for fifty yards.

Like muttering thunder the sound began; and rolled out from the island, rocking sea and air in a mighty wave of increasing, ear-wracking noise. A discharge of big guns, close at hand, could have shocked the aural nerves no more!

Before the face of the rock a curtain of spray and mist, or smoke, had suddenly formed. The crack in the rock was hidden; but the second series of sounds that reached their ears consisted of the plunging of the splintered rock into the sea. The cloud rose higher, hiding the entire face of the cliff. Sea birds darted out of it, screaming in terror, and winged their way over the heads of the watchers in the Red Arrow.

It was several minutes before the cloud of smoke and spray was dissipated. Then, to the eager eyes of those aboard the launch, appeared a yawning cavity in the face of the cliff. A good sized ship (or so it seemed) might have sailed into the cavern thus laid bare to the sun of noonday.

"Start her up, Dan!" gasped Mr. Craig. "I believe Fred has done it for me."

"We may have to blow out some of those chunks that have fallen in the channel," said Mr. Gedney, quietly. "But the sea is very deep right here, and there is no shelving beach. The rock drops right away into deep water. Underneath the surface there was already a passage through the rock; but it was not big enough for the submarine to pass out at. I reckon she'll get out now, all right."

As they ran the Red Arrow in closer she began to feel the heave and thrust of the agitated waters.

"Quite a combobberation kicked up about here," cried Billy, hanging to the wheel spokes and with difficulty keeping the launch on her course. Dan had slowed down so that the Red Arrow barely had headway. They were getting close in to the gaping hole in the cliff and there was danger.

"Look out for snags, Billy!" Dan called out.

As they passed along the rocky shore of the island the seabirds shrieked above their heads and the air seemed to still vibrate from the awful shock of the explosion. At the usual dock nothing was disturbed; but when the party had landed and made their way to the outside cave, they found that the explosion had reached farther than they at first supposed.

"I left the rock-door open," said Mr. Gedney. "And I think it is fortunate I did so, eh?"

The floor of this small cavity was covered with bits of shattered rock. The solid boulder, which Mr. Craig had arranged to swing on a pivot, was split in twain and could never be used to close the opening again.

When they tried the electric contrivance, it would not work; they could not turn on the lights in the tunnel. So, with hand lamps, they pressed on into the gloom. Every incandescent light in the entire string was smashed. The compression of air in the caves must have been enormous the moment after the explosion. The way into the great cavern was clear, however; but when they came out upon the shelf overlooking the yard where the submarine was built, and the boat herself, they found plenty of traces of the terrific shock.

The dynamo was stopped and Mr. Craig did not think it wise to try and start it without going over all the wiring. The roof of the cavern seemed to be quite intact; Mr. Gedney carried a powerful storage battery lamp and the white ray it shot about the cavern was almost equal to a searchlight. This did not satisfy Mr. Craig, however; there was an acetylene searchlight in his plant. They got it out, put it aboard the submarine (which seemed not to have been in the least injured by the blowing-out of the rock-wall) and rigged it forward of the conning tower.

When this lamp was in order they examined the surface of the lake and the roof of the cavern near the opening. The sun streamed into that end of the cave now, but before the inventor ventured to start the mechanism of the boat, the ray of the searchlight was made to course over every foot of the jagged roof just above the new exit from the cavern.

"It looks as secure as the dome of St. Peter's," declared Mr. Gedney. "Come, the boys and I will row down there and view the channel at closer quarters, while you start your dynamo below."

There was a metal lifeboat that belonged to the submarine, and which when not in use fitted into a pocket in the craft's bow. This boat could be got at from outside, as it was intended for an emergency when the submarine was at the surface, and to land in. Mr. Gedney and the boys were soon in the buoyant little tender and rowing toward the mouth of the cave.

The channel was clear. Mr. Gedney sat in the bow with the leadline and measured the depth of the lake every five yards; therefore they moved but slowly. The channel by which they intended taking the submarine out of the cavern had already been buoyed, and most of those floating marks were in place. Therefore it was easy enough to re-chart the course to the very entrance of the cavern.

The various charges of explosives, distributed with great judgment along the wall, and discharged at the same instant, had blown out a passage of ample width—and, it seemed, had blown it out cleanly. There were no reefs in the way; there seemed to be no loose pieces of rock left in the roof. In the broad sunshine of the outer cove, upon which the cavern now opened, the way seemed clear.

When they rowed back to the submarine they knew by the trembling of the long, whale-backed craft, that her mechanism was at high pressure. Mr. Craig came up from below with his face shining.

"Not a thing misplaced!" he cried. "No adjusting to do. Everything true to a hair. Is the way clear?"

"As far as we could see," replied his cousin.

"Then get aboard. We'll run her outside."

Dan and Billy were delighted. They hurried aboard the submarine, and the inventor and Gedney hoisted the tender into its socket and clamped down the plates which covered the small boat. Then Mr. Gedney looked curiously at Dan and Billy.

"How about these lads, A. C.? What would their folks say?"

"We are not going to make a descent, Fred," declared the inventor. "She's safe enough, anyway. They can run out with us, at least."

It was the first time the boys had ever been allowed to descend into the interior of the submarine boat. They went down, the hatch was closed, and the Speedwells followed Mr. Craig into the glass-enclosed conning tower, from which point he could control all the mechanism of the wonderful craft.

They sat upon a seat behind the inventor and watched him working the various levers. Before they were aware of the fact, the submarine approached the exit of the cave. Her searchlight was turned off and the nose of the craft, that had been built in the privacy of the great cavern, was first thrust into the light of day.


XV. — A RESCUE AND A FIND

THE submarine floated with her deck just awash. Her conning tower was about all that could be seen from a distance, and that was like a big glass cheese-cover floating upon the water.

She was governed entirely (as has been said) from this conning tower. One man could sail the wonderful craft, and every part of her was actually under the control of the inventor as he stood before the table which carried the various levers. There was a compass before him in a case that could not be magnetized by the surrounding metals. There was a speed indicator, an instrument that measured the depth of the machine when it dived, and another indicator with two clock-faces which showed the amount of water let into either the forward or the stern tanks, and by weight of which she was sunk.

There was another tier of instruments above these that would be connected with the powerful torpedo tubes with which it was planned to arm her if the United States Navy Department approved of the submarine monster.

The inventor, assured by his cousin that the channel was clear, brought the craft to the new exit of the cavern, and out into the daylight. Her sharp nose did not as much as rub against a reef.

The boys cheered when she was completely clear and speeding along in the open sea. There were no other craft near to observe the strange-looking glass room just awash. Even the black launch the boys thought was Colonel Sudds' boat, had disappeared between the crab-claws at the mouth of Rocky Cove.

Mr. Craig sailed the submarine around Wild Man's Island. He went fast and slow, sailed her in circles—in fact tried her out in every way but one. He did not sink beneath the surface.

"Time enough for that later. My first diving will be done back in the cavern and I shall be alone in the shell, while Mr. Gedney remains ashore to aid me should there be any trouble. I apprehend none; but I could not conscientiously take you boys down in her at present," he said.

Nevertheless, Dan and Billy were delighted to have been allowed to sail at all in the wonderful boat. It was mid-afternoon when they landed in the cavern again. Then Mr. Craig insisted on their waiting for supper. It was therefore nearly dusk when the Red Arrow got under way and the boys left the island, presumably bound for their home.

But Billy had something on his mind and he broached it the moment they were under way.

"Dan, let's go over to Rocky Cove first," he suggested.

"Eh? What's troubling you?" demanded Dan.

"That black launch is troubling me," growled his brother. "I haven't seen it come out of there yet."

"Colonel Sudds has a perfect right to go in there and contemplate the spot where he spent money to dig for treasure," Dan chuckled.

"Yes; but Colonel Sudds isn't at home. Last I heard he and his family had gone to visit his married daughter in St. Paul. What do you know about that?"

"Well, he's loaned the Shoshone to somebody."

"That is what I suppose. But I'd like to know who the somebody is," observed Billy.

"If it will do you any good, Billy, why, we'll run over," agreed Dan.

"Whether it does me any good, or not, I want to peek into the cove."

They did not reach the entrance to Rocky Cove before dark, however, for a small accident happened to the Red Arrow's engine. As the launch finally pushed her nose into the inlet, darkness had actually fallen. Sheltered on the shoreward side by the cliffs, the cove was already under a pall of blackness.

"We can't tell whether the Shoshone is here or not, if she hasn't riding lights lit," complained Dan, as he set their own lanterns aglow.

At that moment there was a report like the explosion of a heavy mortar, somewhere in the cove, the echoes of the blast thundering in their ears from all sides. Instantly the explosion was followed by a ball of fire that seemed to bulge from the surface of the water, somewhere about the middle of the cove. Instantly, too, there were terrified cries. The flames edged out and lengthened until they covered and flared up from the full length of the hull of a twenty-five foot launch. The Shoshone was afire.

The flaming launch was half a mile from the entrance of the cove; but Dan and Billy Speedwell could see two dark figures poised for a moment at the rail of the burning boat. The shouting came again; then the figures vanished. It was plain that those aboard the Shoshone had been driven into the sea.

Instantly Dan sprang to the lever and opened her wide. The Red Arrow pounded away across the intervening water at racing speed. From the other side of the cove there sounded voices, too—encouraging halloos as the fishermen living there put out toward the circle of light cast by the flaming launch.

The fishing boats were near, but the Red Arrow traveled the faster and it was first to break into the circle of light. A cheer went up from the other rescuers. Dan shut her off, for he saw two bobbing black heads in the tide.

"Easy, Billy! Swing her to port!" he cried.

The younger Speedwell obeyed. Dan grasped the shoulders of the first swimmer, who seemed to be almost exhausted.

"Get Chanceford in first, boys!" cried the other person in the water.

"What did I tell you, Dan?" yelled Billy, from the wheel.

"Come here and give us a hand," commanded Dan.

The Speedwells lifted Chance Avery over the rail. Then they turned their attention to the second victim of the accident. It was Mr. Francis Avery, the superintendent of the Darringford Machine Shops at Riverdale.

"You boys were very fortunately in the way," said the older Avery; but Chance said nothing. It was the second time the Speedwells had saved him from drowning.

"Uncle Abram's launch is a total loss, I believe," went on Mr. Frank Avery. "But we had no idea the carburetor leaked until just now. Then, when I went to search for the leak with a lamp, the gasoline fumes caught fire and the tank exploded. Fortunately neither of us caught fire from the flames."

Dan, however, paid little attention to what Mr. Frank Avery said. His gaze was fastened upon something floating on the surface of the cove, and within the circle of firelight.

"Go back to the wheel, Billy," he said, quietly. "Steer half a point off. See that thing bobbing up and down there? I want it."

He had given the fly-wheel a flip, and the screw had started slowly. The Red Arrow moved straight for the object he desired. Dan leaned over the rail, drew the floating article toward him with the boathook, and quickly got it inboard. The Averys looked on curiously.

"What is it, Dan?" demanded the amazed Billy.

His brother brought the object up to him and in the light of the binnacle lamp he displayed a mummyfied-looking bundle, done up in straw matting.

"Our bottle!" whispered Billy, in amazement.

"It looks like we owed ourselves five dollars," chuckled Dan, ripping open the bundle and bringing the sealed soda bottle to light.

"She was sucked out of the cave yonder on last evening's tide," murmured Billy. "The submarine opening cannot be far out in the ocean if it floated in here since then—only two tides, Dan."

"If she ever got to sea at all, Billy," returned his brother.

"What's that?" demanded Billy, sharply.

"How do we know the submarine passage from the cave in that cliff, opens into the ocean? Why not here in the cove?"

"By crickey, Dan!" ejaculated Billy, in an awed whisper. "Then if it's a straight passage it would come right out under the Slide, wouldn't it?"

"It looks that way," admitted Dan.

"Maybe the old Admiral is right. Perhaps some huge ledge of rock fell and covered the narrow inlet where the Fannie Hendricks lies, and there is an open water-way under a part of the Slide."

"Hush, sharp ears yonder," advised Dan, nodding at the Avery brothers.

"You're right," growled Billy. "And they weren't snooping around here for nothing, either. You remember that Mike MacCormick said Chance must have taken out the cabin window that time we imprisoned him aboard the Red Arrow. I believe he followed us ashore and heard us talking about the emeralds."

"It may be," admitted Dan, slowly.

"But do you believe it is possible that there is a passage here under the fallen rubbish of the Slide?"

"How can we tell? How did that bottle get here in the cove so quickly, if that is not a fact?" demanded Dan.

"Gracious me, Dan! Maybe we're on the brink of a big discovery. Could we dive down there and find the passage?"

"How long do you think you can hold your breath?" chuckled his brother. "Do you think you could dive into the lake in the cavern there, and swim clear through the passage to the outer air?"

"Well," grumbled Billy, "how about a diving suit. We might get one and try it. How does that strike you?"

"Not so bad for a first effort," laughed Dan. "But I believe I know a trick worth two of that."

"What is it?" cried Billy.

"Mr. Craig's submarine boat," whispered Dan. "Let's take him into partnership and really make an attempt to find the wreck of the Fannie Hendricks—if she's where the Admiral says she is."

"And the Dardanelle emeralds!" cried Billy, in delight.

At that moment a voice spoke right behind them. It was Frank Avery. For the time Dan and Billy had forgotten the presence on the launch of the brothers.

"Say, are you fellows going to stay here all night?" he demanded. "Suppose you put us aboard the fishing boat yonder. I believe she has an auxiliary engine and we can get Uncle Abram's launch towed ashore and beached."


XVI. — DAN SPEEDWELL'S GREAT DIVE

"DO you suppose he heard?" whispered Billy to Dan, as the latter turned to go back to the engine of the launch.

"I don't know—and I don't much care," returned the older Speedwell.

"I tell you, Dan, they're both wise to the story the Admiral told us. Maybe they had heard something about the emeralds before from Colonel Sudds."

"Keep still. We'll get rid of them both first of all. At least, I don't think they heard anything about the bottle," and Dan chuckled, hiding the glass flask under his coat.

But the older Speedwell was now quite as excited over the possibilities surrounding the incident as was Billy. If the Admiral had told them the truth there was a fortune concealed in the wreck of the old sloop, under the Slide. And if the bottle had come through a submarine passage from the cavern in the adjacent cliff, that passage might be utilized in reaching the wreck of the Fannie Hendricks. Of course, the possibility was a far-fetched one; nevertheless Dan could not help giving the thing a deal of thought.

They were both glad to get rid of the Averys. Francis and Chanceford went aboard the fishing boat without as much as thanking the Speedwells for what they had done for them; but that did not surprise Dan and Billy. They had not expected gratitude from either the superintendent of the Darringford Machine Shops, or from his brother.

"I guess they were hanging about the cove with some scheme in their heads about those lost emeralds," declared Billy, as he steered the Red Arrow for the light that now sparkled on one crab-claw which separated the quiet cove from the sea.

"Perhaps not," said Dan, quietly.

"And perhaps Chance didn't hear us discussing the Admiral's story?" exclaimed the younger lad, with scorn.

"We have no way of proving our suspicions, one way or another, have we?" returned Dan.

But it was only two days later that even Dan had reason to accept Billy's suspicions of the Averys as very probably true. Mr. Speedwell had been true to his promise—he gave his sons most of their time for a week or two, and Dan and Billy took a party of their boy friends out on the Red Arrow only two days after the blowing-out of the rock-wall on Wild Man's Island. The other two lads were anxious to see the place where the submarine boat had been built.

For Mr. Craig's secret was a secret no longer. The papers had long articles in them—displayed prominently on the first pages—about the monster of the sea that had been building at Wild Man's Island, and was now about to be tried out by the Government.

So the Speedwell boys were much sought after by their school chums, and on this particular day half a dozen of them, beside the owners of the Red Arrow, boarded that launch for a voyage as far as the inventor's isle.

But Billy had another scheme in his mind, too, and he broached it on the quiet to Dan as the launch sped down the river and out into the open bay.

"We want to see the Admiral again, Dan," he whispered. "Why not try and get him to go along with us? And after we have been to the island, run over into Rocky Cove?"

Of course, at present it was useless to think of discussing the matter of the shipwrecked Fannie Hendricks and the lost emeralds with Mr. Craig. The Speedwells did not even know where the inventor was on this day—perhaps making his trial trip under the sea for the Assistant Secretary of the Navy.

"I don't mind," agreed Dan, after a moment's thought. "Only you go ashore and interview him, Billy, and warn him to speak only to us about the emeralds—and not in the hearing of the other fellows."

"Trust me for putting the old gentleman wise," returned Billy, with great confidence.

And it did not prove a hard matter to secure the Admiral for a day on the Red Arrow. He promised to make one of his famous fish-chowders for dinner, if the boys caught the fish, and this was hailed by the Riverdale lads with great rejoicing.

But Billy found time to take Dan aside as they sped out past the breakwater, and aimed the nose of the Red Arrow for Wild Man's Island. He confided to him something that the Admiral had told him when he had gone ashore to engage the old seaman for the day.

"Those Averys have been smelling around about the treasure—I told you so!" whispered Billy, eagerly.

"How do you know?" demanded Dan.

"The Admiral told me so."

"You mean that Chance Avery had the nerve to go to the Admiral, after running the old man down that day?"

"Why, he made that an excuse for calling on the old fellow," said Billy. "And he came with his brother. At least, I suppose it must have been Mr. Frank Avery who was with him in a hired automobile. They were there yesterday—after having been over to the cove, you know, and nosing about there. By the way, I wonder what Colonel Sudds will say to them when he finds his launch burned to the water's edge?"

"We haven't got to worry about that," Dan observed. "But what more did the Admiral tell you, Billy?"

"The old fellow gave Chance the sharp edge of his tongue, I reckon," chuckled the younger lad.

"I expect Billings would not be too tender with Chance."

"I guess not. But Chance made the bluff that he had come to beg the Admiral's pardon—and incidentally to learn if you had really given the old man the five dollars you made Chance disgorge for a wooden leg. The cheek of the fellow! He tried to make the Admiral believe that he had sent that five dollars to him of his own free will."

"That's like Chance," responded Dan, nodding. "As you say, he's foxy."

"I should say he was," exclaimed the eager Billy. "And then he began to try and pump the Admiral about the Fannie Hendricks."

"The Admiral says so, does he?"

"He wanted to know who we had been telling the story to, and I told him we hadn't even mentioned the matter at home."

"And we haven't," agreed Dan, nodding.

"So I assured him. Then the Admiral said that Chance and the man with him said they had heard about Colonel Sudds trying to dig down to the wreck, and they asked if there really was treasure hid in it?"

"What did the Admiral tell them?"

"The old fellow says he was wary about it. He began to smell a rat right away, and not knowing who they got their information from, or how, he ‘battened down his hatch'—so he says—and told them nothing."

"They're after the emeralds, just the same," murmured Dan, thoughtfully.

"And you can wager that Colonel Sudds didn't give them their first idea about the treasure," Billy declared. "We did that ourselves. Chance fooled us the night we had to imprison him aboard the launch."

"I am afraid you are right, Billy," admitted Dan. "But we can't help that now."

"No. But it's up to us to get a move on if we are going to make the first try for the wreck," declared Billy.

"And how shall we go about it?" asked his brother, curiously.

"There's no better way than you suggested—get Mr. Craig interested in the story. Get him to take us down in the submarine with him, and see what the bottom of the cove looks like, on that side where the old sloop is buried."

They could talk no further on this topic, for the other boys were becoming suspicious of their whisperings. The Admiral, however, kept the whole crowd amused by tales of his adventures at sea and in foreign lands, until they came to the island.

The boys marveled at the great hole blown in the cliff. Mr. Gedney ran out of the cavern in his cousin's turbine launch, to warn them away from the leased island; but when he found that it was the Red Arrow with the Speedwells and their friends, he readily gave them permission to land upon the seaward side where the fishing was good from the rocks.

As soon as the dinner was eaten, however, the boys wished to do something more. The island's resources were already known to them all, and when Billy suggested running over to Rocky Cove (with a wink for Dan's benefit), they all clamored for it.

"And maybe we'll pick up our bottle that we set adrift," said Jim Stetson. "It ought to be somewhere between the island and the cove, eh?"

The Speedwells had agreed to say nothing regarding the finding of the bottle; at least, not at present. This was a secret between Dan and Billy alone.

And there was so much fun and skylarking going on aboard the Red Arrow that the Speedwells' guests did not notice the secret conferences of Dan and Billy, with the Admiral as a third party.

"We want you to take the wheel, Admiral," whispered Billy to the old seaman; "and tell us when to drop anchor at the very nearest point you can take the launch to the spot where the Fannie Hendricks lies."

"Aye, aye, me lad!" returned the Admiral, hoarsely. "I can lay her by that steep shore where the Slide stopped on reaching the water. That's right at what was the mouth o' the inlet where we anchored the sloop, back there in '76. There was a deep hole there then, and there's a deep hole there now. I know, for I was castin' the lead-line when we crept into that there moorings on the night I tell you of, and I've measured the depth of it since."

"When Colonel Sudds was thinking of trying for the treasure?" asked Billy.

"Yep—and since. I tell ye what, there's times when I've believed something might be got out of yon wreck," growled the old seaman. "Of course, you boys can't do nothing; but men with money——"

"Will you give us all the help and advice you can about securing those emeralds?" demanded Billy, bluntly. "We to give you a share of them if we find them?"

"Bless your heart, lad," chuckled the wooden-legged man, "I'll do that much for a mighty small share of what them emeralds was wuth. Bet you I would."

"We may hold you to that, Admiral," said Billy, seriously.

"How you going about getting under that heap of rubbish?" demanded the Admiral, pointing to the Slide, into view of which the party had already sailed.

"That would be telling you more than we know ourselves," said Dan, quickly. "But Billy and I have agreed to try."

"You're great boys," chuckled the old fellow. "Go in and win, says I."

The Red Arrow was sailed to the spot the Admiral indicated, and there, close in shore, the anchor was dropped and the launch swung at her moorings in quiet, deep water. It was an almost breathless afternoon, and the sun had been hot all day. It was Monroe Stevens who suggested a dip in the cove—and it was just what Dan Speedwell had been waiting for.

Dan was a wonderfully sure swimmer; he was something better, too—Billy and the other fellows declared he was a regular fish in the water. It did seem as though the older Speedwell boy was thoroughly at home in the sea, and never seemed to tire of the sport of swimming.

Now he was one of the first stripped and with bathing trunks on. The water was warm in this cove, and after a plunge or two Dan felt that his own blood was attuned to the temperature of the water.

One of his favorite tricks was to sink under the surface and remain beneath for many seconds longer than any other boy in Riverdale. This feat he had tried again and again. But, on certain occasions, when Billy and he had been swimming by themselves off old John Bromley's wharf, Dan had gone down with a weight in each hand, and remained so long that his younger brother had been actually frightened.

Now, while the other fellows were skylarking in and about the launch, and the Admiral was smoking a pipe, Dan stuffed his ears and nostrils with medicated cotton, seized one of the ballast weights in both hands, and leaped overboard. Billy, aware of what he intended doing, watched eagerly for results. A full minute went by—and it passed quickly. Then followed thirty seemingly slower seconds—then thirty more that dragged most awfully. The younger Speedwell always felt some anxiety when Dan exhibited this feat. And it would have been exceedingly dangerous for another boy to try it.

Suddenly something light in color flashed into view deep down in the water. For a breath Billy thought it was a fish. Then, as it shot toward the surface, he knew that it was Dan's body, relieved of the weight he had carried, and Billy stretched down both hands to seize him as he broke from the sea.

But Dan came up with his face shining. He seized Billy's wrists and helped himself aboard, but breathing deeply and strongly.

"That certainly is a deep hole," he said to the Admiral, when he could speak. "And I believe it's as wide as a ship channel!"

"As to that I can't say, my lad," returned the seaman. "But I knows it is deep down."

"How about the submarine passage?" whispered Billy.

Dan's eyes fairly snapped, and his face was alight with triumph. "I believe I've found it," he returned, in a low tone. "I'm going to dive this time—it will carry me farther in. I know the direction now. Just watch out for me when I come up."

"Be careful, Dannie," murmured his brother, with unwonted caution.

"That's all right, old boy. Be ready to grab me. The tide is running out; if the worst should happen, I'd be sure to be carried back into the cove here, and you'll see me."

"For pity's sake, don't try it!" gasped Billy, much frightened.

"Nothing venture, nothing gain!" quoted Dan Speedwell, putting the wads of cotton back into nostrils and ears. "Now, stand by me, Billy."

He clasped his brother's hand warmly, took in and discharged several deep breaths; then, springing to the rail, he leaped head first, describing no graceful curve, but shooting away from the boat's side like a dart.

He took the water at a long slant, and they could follow his course as he went down into the depths. But within a few seconds the shadows swallowed him; the ripples the passage of his body had made, ceased to disturb the surface—and he was gone.


XVII. — WHAT WAS IN DAN'S HAND

DAN SPEEDWELL'S body cleaved the water on a long slant when he dived from the deck of the Red Arrow. The other boys (all but Billy) were gamboling in the water on the other side of the launch, and did not notice his departure.

He felt the force of the out-sucking tide through the under-passage before he was his own length beneath the surface; but it was not as yet an unsurmountable current. The momentum he had gained was sufficient to carry him deep down into the water, without swimming.

But the moment he felt that the current was too strong for this momentum he began taking swift, strong strokes, downward and slanting in the same direction. Dan opened his eyes; but the light was so dim that he could see nothing but a brown wall, with streaks of white in it, ahead of him. Through this wall of shadowed water he cleaved his way until suddenly—quite startlingly, indeed—he reached the bottom.

He seized upon a stone and clung to it. The buoyancy of his body was so great down here that he would have instantly shot to the surface had he not got this grip on the rock.

Half lying on the sandy bottom he looked up. He knew, from former experiences, that he should be able to see the sun—a ball of pale fire—on a cloudless day like this, provided the heavens still overarched him.

But that glowing ball was invisible. Dan had left a glorious and unflecked blue arch above the launch when he dived from her deck. Where was the sun now?

And as the question flashed into his mind the answer followed instantly on its trail: The roof of a submarine cavern interposed between his view and the sky.

It was true. Here was the passage he and Billy had suspected existed under the great mass of fallen rock and debris which made up that awful avalanche that had fallen from the cliffs so many years before. Some huge ledge of rock, slipping down with the avalanche, formed the roof of this cavity. The wash of the tide into the cavern Dan and his young friends had found a few days before, had cleared the loose material from a wide space under this ledge.

The facts were now assured. Into Dan Speedwell's mind came the final and most important question:

Was the wreck of the Fannie Hendricks still here, and could she be got at?

It had taken Dan less than a minute to reach the bottom of this gulf. He still had a full minute to stay and plenty of reserve force to take him to the surface again. Besides, he calculated on the out-suck of the tide to carry him in the right direction.

He wasted little time clinging to the stone, and gazing up and backward. He knew he was in the mouth of the tunnel at least. Somewhere before him lay the wreck of the old sloop, if the Admiral's statement was a fact. Dan felt that—if possible—he must learn the truth about this wreck, here and now.

There was the tug of the out-going tide to fight as well as the natural uplift of the sea. But Dan Speedwell was a strong swimmer and he knew how to take advantage of his position here on the bottom of this submarine tunnel.

He scrambled on for a few yards and then cast himself forward with strong and long strokes, rising but little from the bottom of a passage. He could see nothing; but of a sudden he bumped into some great bulk, around which the water swirled and eddied.

He knew it was not a rock by the touch of his hands. It was metal—and it was of huge size.

Seconds were precious. Dan began to feel the pressure in his lungs that warned him he must return to the surface. There was a ringing in his ears, too; and the plucky youth knew his time was about up.

Once more, however, he flung himself forward. He slid along the length of this strange bulk. And then—in a flash of comprehension—he understood what it was. It was the copper sheathing of a ship's hull.

He had found the Fannie Hendricks.

The boy was half unconscious now, however. He scarcely knew what he did, and with a stubbornness that was likely to prove fatal, he sought to remain beside the hidden wreck.

The lift of the water was bearing him up, however; he could not fight against it longer. Besides, he could not cling to the metal sheathing of the sunken hull; it was too slippery.

He grasped at it. He fought to remain on the bottom. There was nothing but mud and slime to seize, however, and he knew that he was being swept away from the wreck. The out-going tide bore him out of the submarine passage.

Dan really lost consciousness then. He had overstayed his time!

On the deck of the Red Arrow Billy was driven almost frantic by his brother's delay. Monroe Stevens suddenly scrambled over the rail from the other side, and demanded:

"Where's Dan, Billy? Where'd he go to?"

"He dived down there," muttered the younger Speedwell, pointing. "He's—he's been gone a long time."

"You don't think anything's happened?" cried Wiley Moyle, joining them.

"He never stayed down so long," gasped Billy.

"We'll try for him," declared Monroe, and instantly dived over the rail. Wiley followed; but Billy did not dare do so. If Dan bobbed up to the surface now, the younger lad knew that he would need assistance.

Monroe and Wiley Moyle disappeared, too. Billy was half over the rail, trying to peer down into the sea, when a cry sounded from beyond the launch, and farther out into the cove. The old Admiral rose up himself and shouted:

"He's got him! There he is, boy!"

Billy sprang up and ran to the other side. Monroe was bearing up the head and shoulders of Dan Speedwell, not many yards beyond the launch.

The other fellows rushed to the rescue. They bore Dan alongside the Red Arrow. Billy and the Admiral seized the half-conscious youth and drew him aboard, while all the others scrambled over the rail.

"He's all right—or he will be in a minute, Billy," Monroe declared, with confidence.

"He looks bad," whispered Billy. "Lay him down flat, boys. Put his feet a little higher."

"Don't you fear," repeated Monroe Stevens, "Dan's far from being drowned. There, his eyes are open."

But they closed again. The color did not immediately return to his cheeks. His breathing was very labored. And as he lay there on the deck surrounded by his young friends, it was suddenly noticed that his hands were tightly clenched. He seemed to have squeezed some of the mud at the bottom of the cove in both fists.

Billy, on his knees, seized one hand and tried to open it. The fingers were clenched tightly—so tightly that Billy could scarcely unclasp them. But, suddenly, the half-drowned lad's muscles relaxed. His hand opened. The dirt he had seized upon in his last attempt to remain on the bottom, fell from his opening hand—and with it fell something that brought a chorus of excited cries from the spectators.

"Look at that! What is it?"

"See that stone, Billy!"

"It's a piece of green glass!" declared Wiley Moyle. "Where did Dan get it?"

But Billy had seized upon the object with a great cry. The Admiral likewise grasped at the green stone in Billy's open palm, and dropped his pipe upon the deck.

"Keel-haul me!" ejaculated the ancient mariner. "He's found it!"

Billy could not speak. He had never had in his hand so large a gem before. But he had seen emeralds, and he knew that this strange green stone, with the sparks of glittering fire in its heart, must be an emerald of great value.


XVIII. — "THE SPEEDWELL COMPANY, LTD."

DAN began to splutter a little then. He gasped, rolled his head back and forth on the deck, and then sat up.

"More salt water in your system than you ever got before—eh, Dan?" cried Monroe Stevens.

But Billy was staring at the wonderful gem in his hand. He knew that Dan was all right again and had promptly forgotten everything else but the emerald.

"What's the matter with you, Billy?" demanded Jim Stetson. "Is there something odd about that chip of a glass bottle?"

"Is that all Dan could bring up with him off the bottom of this cove?" exclaimed Wiley. "See here, Dannie; where'd you get this thing?"

But the Admiral reached out and took the great emerald between his thumb and finger.

"It's a real one," he stammered. "It's bigger than any o' mine—a deal bigger. Why, boys, this is one o' the finest of the whole lot, I declare!"

"Whatever are you talking about, Admiral?" ejaculated Monroe Stevens.

Dan's own eyes were, fixed upon the glittering stone, in a most astonished expression.

"What's the matter with you Dannie?" exclaimed Wiley Moyle.

"Where did that thing come from?" gasped the older Speedwell.

"Why, Billy just took it out of your hand," said Monroe, "Don't you know where you got it?"

"It's an emerald!" exclaimed Dan.

"It's more likely a piece of broken glass," snorted Wiley.

"It is an emerald," cried Monroe, drawing nearer. "You know it is, don't you, Mr. Billings?"

"It's one of the Dardanelle emeralds—sure as we're not all fish I" exclaimed the Admiral, emphatically.

"And Dan don't know where he got it," scoffed Wiley. "Why, a mermaid must have given it to him while he was down there."

Jim Stetson had taken the gem from the old mariner and was scrutinizing it closely.

"My aunt has a string of small emeralds. They used to be very fashionable and I heard her say the other day that they were coming in fashion again and were worth as much as diamonds."

"Worth as much as diamonds!" gasped Wiley. "You're fooling."

"No. She said perfect stones, and well matched, would be worth as much as diamonds of equal size."

"Why, that thing there is worth five thousand dollars then!" hooted young Moyle. "It's ridiculous!"

"Hush up, Wiley," commanded Monroe Stevens, seriously. "If this is a real emerald——"

"And if it isn't a real one it's a mighty good imitation," put in Jim.

"I believe you there, Jim," agreed Monroe.

Here the Admiral took a turn in the discussion: "Who says it isn't a real emerald?" he demanded, in disgust. "Why, you lads never see no emeralds to speak of; but I've seen a bucketful to wunst."

"Whew!" exclaimed Wiley, under his breath. Wiley was certainly a doubting Thomas.

"I don't know just what the Admiral is getting at," said Monroe Stevens, with gravity; "but like Jim, I believe that to be a very fine emerald. Dan, that certainly was a lucky dive for you. If the stone doesn't sell for five thousand dollars, it will sell for more money than any of us ever had in our hands at one time."

"An' it ain't a patch on what is still down there," rumbled the Admiral.

But Dan began to recover his composure, as well as his breath, now; he gave the old seaman a warning glance, while he said:

"I picked that stone up off the bottom of the cove. There can be no doubt of that; but I was not conscious that I had done so. It was just by chance that I seized it. I can tell you fellows, honestly, I saw nothing down there that looked like an emerald—or anything else of value."

"Wonderful!" exclaimed Monroe.

"It beats anything I ever heard of!" Jim Stetson exclaimed. "And aren't you Speedwells the lucky chaps? If the emerald is flawless you'll have a pot of money."

"If it is an emerald," put in Wiley.

"That's all right, Wiley," said Jim. "How'd you like to dive down and see if you can find another?"

"If it's worth anything I'd like to have it, all right," admitted Moyle. "But I'd never be able to find one on the bottom of this cove—for I couldn't get down so deep. Dan's half fish, anyway. And, besides, if we raked over the whole cove with a fine tooth comb, we probably couldn't find another thing like that green stone."

"Wiley doesn't want to admit it's a gem," said Jim, slily.

"If I'd been the one to find it, it would turn out to be nothing but a piece of an old bottle, I know," grumbled Moyle. "The Speedwells do have the luck, I admit. Maybe it is worth good money."

The three in the secret gave no further information to the other boys; but for the rest of that afternoon, and until the Red Arrow reached Riverdale again, the main topic of conversation was Dan's lucky find.

The Admiral took the Speedwells aside before he left them near his own little red house on the Barnegat road, and said:

"Now, my lads, if you propose to do anything towards the findin' of them emeralds, strike while the iron's hot. There's more than you will know: about the findin' that there gem before midnight. Understand me, lads?"

"I know," said Dan, quickly. "All these fellows will tell their folks, and it will be all over Riverdale in an hour."

"Quite so, my lad. And them that is already a-lookin' for the treasure will hear of your find, too."

"The Averys!" exclaimed Billy.

"That's the ticket," said the Admiral.

"I tell you what we'll do," said Dan. "We'll come down after you in the Red Arrow to-morrow morning, and will you go over to. Wild Man's Island with us to see Mr. Craig? Mr. Gedney said he expected him and the submarine back tonight."

"I'll do so, my lads," declared the Admiral. "For if there's any way of helpin' you beat them sculpins that come nosin' around me the other day, for news of the Dardanelle emeralds, I'm the lad that's heart and hand ter help ye, believe me!"

With this agreement the old seaman had gone ashore. When the Speedwells got rid of their other guests at the Colasha Boat Club float they ran the Red Arrow to her usual moorings at John Bromley's dock—which was a point not far from the Speedwell farm.

Dan placed the beautiful jewel he had found that day in his mother's hand and told her and Mr. Speedwell just how he had come by it. He did not go into all the particulars of his great dive, or of the peril he ran; nor did he relate all the details of the old Admiral's story about the loss of the Fannie Hendricks.

He spoke of his own and Billy's desire to try and get at the wreck in Mr. Craig's new submarine boat, by the use of diving suits. Mr. and Mrs. Speedwell did not take very kindly to this, fearing for their sons, and Mr. Speedwell warned them to be very careful if they made the trip.

The single emerald Dan had found, however, was most surely a very valuable jewel. If they recovered no more of the lost treasure of Rocky Cove, the sum realized from the disposal of this gem would be sufficient to give Dan and Billy a splendid start in life.

This talk occurred in the evening of the day Dan had found the emerald. Before mid-forenoon next day they were at the Admiral's place and found the old sailor ready and eager to sail with them.

"Ahoy, my lads! Dick Billings is the lad that's as eager for this ventur' as ever he was for anything he undertook," he hailed. "When him and the others j'ined Marksman on that trip to the Dardanelles, Dick warn't no more willin', I tell ye. The blood's coursin' some strong in my old veins yet. We'll git them emeralds, lads—I feels it!"

He was ready to go with the Speedwells and stay a week, if need be. He had engaged another pensioned sailor to stay at the little red house and to fire the sunrise arid sunset guns and raise and lower the flag as per schedule.

"And if he don't do as he's told, I'll know it," declared the Admiral. "There's a man as lives down the road a piece, and he's to Mark down on paper the exact minute them guns are fired. Then we'll compare his logbook with the almanack, and if they don't agree, I'll stop that sea-sarpin't plum duff and 'baccy for a week!"

The Red Arrow got under way again and soon passed out of the bay. Dan aimed her sharp prow for Wild Man's Island. On this trip they did not seek to land at the old docking place, but drove the launch directly to the wide entrance to the cavern. There Billy shut off the power and Dan hailed as loudly as he could.

Mr. Craig himself came out in the tender of the submarine and, seeing that there were only Dan and Billy with one old man, rowed to them and came aboard.

"So you have come out to congratulate me?" he said. "That is mighty nice of you. I have every reason to believe that I shall finally be repaid for all my work and worriment. The Navy representative expressed himself as completely satisfied. He will make a favorable report to the Naval Board. My submarine will be adopted by the Department, I believe."

The Speedwells, although so full of interest in the emeralds and the possibility of getting at them with the aid of Mr. Craig's wonderful boat, could not fail to be much delighted by their friend's good fortune. They did indeed congratulate him heartily.

When the inventor was introduced to the old seaman, the boys gained Mr. Craig's attention and told them all about the lost treasure of Rocky Cove. Whether the inventor believed the Admiral's tale of the emeralds, or not, he was fain to believe in the genuineness of the single gem that Dan had found, and that he had now brought to show Mr. Craig.

"It is, indeed, a fine emerald," declared the inventor. "Mr. Gedney could tell you more about the value of if than I can. He's interested in such things. But he's gone to the mainland to-day in the turbine. Now, boys, what is it you want me to do?"

Dan went into details then. He showed Mr. Craig how he thought that by the use of the submarine they could get into the passage under the Slide at Rocky Cove and learn, perhaps, in what condition the wreck lay.

"She's there, I know," he declared. "But how she lays, and what we would have to do to get into her, I cannot say," Dan observed. "We'll have to get diving suits, I suppose——"

"I have a diver's outfit," said Mr. Craig, briefly. "I had to know something about that work before ever I thought of launching the submarine. The entire paraphernalia is here."

"Bully!" exclaimed Billy Speedwell.

"Then what we want, sir, is to have you go in with us for the hunting of this treasure," said Dan, eagerly. "Will you put your knowledge, the use of your boat and diving apparatus, and so forth, against the Admiral's first-knowledge of the treasure itself, for half of the proceeds of the venture? Billy and I will share the other half. Maybe you think that is too big a share for us——"

"No. You are the promoters," said Mr. Craig, with gravity. "Without your interest and work, the Admiral here, and I, would never have come together, and if we find any treasure I am willing to share it as you suggest."

"Me, tool" exclaimed the seaman. "Why, bless yer heart, lads, Old Sudds was only goin' to give me ten per cent, on all he found."

"Then it is settled, exclaimed Billy, with joy."

"And we can get right to work on it, Mr. Craig?" cried Dan.

"We certainly will, my boy. The firm of ‘Speedwell Company, Limited; Treasure Seekers' is actually launched; and, being launched, it will proceed to get immediately to the work it has been formed for. Sail her up into the cave, Billy. The submarine is ready for sea. We'll go over to Rocky Cove at once, and make a preliminary sounding."


XIX. — DEEP BELOW THE SURFACE

THE boys were delighted with Mr. Craig's prompt agreement to their desire; and as for the old Admiral, he grinned broadly. They ran the Red Arrow into the old docking place of the submarine. There were lights lit at the end of the cave and they could plainly see the shining, cigar-shaped hull of the wonderful boat, riding high out of the pool.

"Never thought I'd ever go aboard one o' them iron-pots again," declared the Admiral. "But this ain't jest exactly a navy vessel, is she?"

"Not yet," returned the inventor. "She is mine still."

They went aboard after mooring the launch. The tender was shot into its pocket on the port bow of the submarine, and the plates clamped down over it. Mr. Craig explained that, on the other bow, and in a somewhat similar pocket, but arranged only to open from within, was another boat having chambers 'fore and aft that could be filled with compressed air, and which could be easily entered from the interior of the submarine.

"If anything should happen while the submarine is below, so that it should become necessary to leave her and escape to the surface, the crew of the submarine will enter this second tender, open the pocket by means of a mechanism of my own invention, and the small boat would shoot up to the surface. There the closed hatch of the tender can be opened, a mast stepped, and the crew would be able to escape, even in mid-ocean."

The quartette went below and the hatch was sealed. Not a drop of water—or air, while the boat was on the surface—could get into the submarine. The atmosphere of the passages and the conning tower was fresh enough, however; and Mr. Craig showed them how he governed the supply of pure air throughout the boat from certain great tanks where it was held under compression.

Electric bulbs gave plenty of light throughout the craft. The long central cabin—the officers' quarters when it became a naval boat—looked really cheerful. Out of this cabin opened the sleeping rooms. The submarine could comfortably house four officers and ten men—a particularly large crew for such a craft. Yet, Mr. Craig assured them, one man could govern all of the movements of the submarine perfectly.

This fact he proceeded at once to prove. They all went into the glass room. The heavy plate glass was strengthened by many bands of aluminum, and was braced in such a way that the pressure of the water at an enormous depth could not crush in the walls.

The Speedwells and Mr. Billings sat down out of the way and Mr. Craig gave his undivided attention to the manipulation of the levers before him. As before when the boys had voyaged in the wonderful craft, she started without their knowing it. Suddenly they were out of the cave in the bright sunshine.

Mr. Craig scrutinized the sea all about, took a look at the indicator which would warn him of the approach of any other craft with sufficient metal about her to affect the magnetized needle, and then turned to speak to his guests.

"I do not claim any particular speed for this craft; but she is silent, safe, and—I believe—wonderfully efficient," he said. "And the Secretary of the Navy agrees with me. She will be able to creep up on an enemy, torpedo her, and get away without making any more ripple or disturbance at the surface than a fish."

"But how about one o' the cruiser's big guns ketchin' yer propellers?" asked the sailor, hoarsely.

"It would have to be a big gun indeed whose shot would dent this armored hull—even at the surface. And she does not have propellers—not in the ordinary sense."

"No propellers?" ejaculated Dan and Billy.

"No. Propulsion is obtained on the "squirt-boat" plan—a scheme of operating a submarine which, I believe, I have finally perfected. There are no propellers to be shot away. Water is taken into tubes on either side of the lower hull, and near the stern. This water is forced out by pumps run by two engines, each of fifteen hundred horse power. These engines are run by kerosene. The engines and their fuel tanks constitute most of the weight in the boat when she is at the surface."

"But if they should take a pot-shot at your glass cage?" suggested Dan.

"That certainly would finish us, wouldn't it?" said Mr. Craig, chuckling. "But this 'glass cage', as you call it, Dan, is merely for time of peace. In time of war it is removed, it being really a superstructure. All this paraphernalia in front of us," pursued Mr. Craig, pointing to the two-tiered table holding the instruments and levers, "you will notice is below the level of our deck. This conning tower of glass is removed in time of war and a hatch, with a small aluminum tower, with narrow, visored ports in it, is battened on in place of the glass house."

"By crickey!" exclaimed Billy, "it is just the most wonderful thing I ever heard of—isn't it, Dan?"

"It certainly is that," admitted his brother, quite as enthusiastically.

"Now, boys, come here both of you and watch me. I will teach you how to run my boat—and that is something that nobody else knows as yet, save Mr. Gedney," said the inventor, kindly, knowing full well how much interested Dan and Billy were in anything of a mechanical nature.

While they were working their way between the island and the mouth of Rocky Cove, both Dan and Billy Speedwell tried their hands at running the smoothly working submarine. They learned to steer her, to go fast or slow, and to stop or start the boat.

As they approached Rocky Cove, however, the inventor took his place before the table again.

"There are several fishing boats in the cove this afternoon. And I saw the auxiliary schooner, Midget, of Riverdale, go in early this forenoon," said Mr. Craig. "We might as well go in without attracting any attention."

"Who do you suppose has hired the Midget to come down here in?" exclaimed Billy. "Her owner never goes fishing unless there is a good price in it for him."

"There she lays over yon now," said the Admiral, whose eyes were keener than even the boys' own, in spite of his age.

"Is that her by the Slide?" cried Dan.

"That's the schooner," grunted the Admiral. "And she's lying about where your launch was anchored yesterday."

Billy was already excited. "She's there for no good purpose!" he exclaimed. "The story of that emerald you found was all over town last night, I believe. If those Averys know as much as we do about the treasure, I bet they'll have a try for the wreck."

"But they haven't the help of Mr. Craig's submarine boat," returned Dan, with confidence.

"And we will see if the submarine is of any practical use in seeking out this old wreck," said the inventor, calmly. "Now, boys, we're going below. You have been just as hermetically sealed from the outside air for half an hour and more as ever you could be at the bottom of the sea. You have felt no ill effects from such a condition, have you?"

"No, sir!" they chorused.

"Then we will go down. The channel into the cove is deep enough to float a ship of war."

"It is that," agreed the old Admiral. "I know all about these soundings."

The Speedwell boys did not really see when Mr. Craig touched the proper lever; but suddenly Billy cried:

"We're sinking! See the water, Dan!"

They were Indeed sinking. The submarine was scarcely under headway, and they were sinking into the depths of the sea on an even keel.

The little waves lapped against the "glass cage," as Dan had called the conning tower. They came higher and higher until with a murmur which was almost born of fear, Dan and Billy fell back upon the bench and saw the headlands of the cove, with the life saving station on one hand and the lighthouse on the other, utterly blotted out by the sea.

The greenish, and white-streaked mass, always in motion, rose over their heads. It washed over the roof of the conning tower. The submarine continued to sink.

Dan and Billy unconsciously squeezed each other's hands. This was what they had been longing for—what they had looked forward to for months. But the actual realization of their hope was so different from their expectation that they really were shaken by something akin to fear.

There was no physical change in their feelings.

If they had shut their eyes they could not have told when they began to descend into the sea, for instead of diving, the inventor was allowing both the forward and stern compartments to fill with water in equal parts, and the keel was kept even.

But the water into which the boys stared seemed so different from the air.

There was plenty of light from above—the light of the brilliant June sun shining upon the sea. Mr. Craig had shut off the electric lights in the conning tower when they had first come out of the island cavern. As the submarine sank it began to grow dusky in the glass room where the boys and the Admiral sat in silence with the inventor of the submarine.

Suddenly the old sailor uttered an exclamation and started back from the glass partition against which he had been leaning. Even Dan utter a cry of fright.

A head, with huge, goggle eyes, and a strange looking appendage nodding before its huge mouth, had appeared like a goblin—the product of some nightmare—close against the glass. Mr. Craig chuckled.

"It's only a fishing-frog," he said, quietly. "You boys have often caught them, I warrant. But the glass slightly magnifies everything outside, and that creature is a particularly large one."

A flash of a dark body, with a streak of light underneath, startled them on the other side of the room.

"A baby shark. They do lots of damage to the fish-pound nets along the shore here," again explained Mr. Craig.

His matter-of-fact tone, and his natural explanations put the boys on their mettle again. They began to breathe more freely and to stare about them for other wonders.

Suddenly the submarine seemed to settle down with a little jar. They realized that she was no longer moving. The light from the sun above was now very dim. They were deep below the surface.


XX. — WILL IT BE A RACE?

"WE are now lying immediately within the two claw-like capes at the mouth of Rocky Cove," said Mr. Craig, quietly. "I believe we are about equally distant from both points of land. You followed the course, Billings?"

"Aye, aye, sir," answered the startled Admiral, who, like the Speedwells, was a good deal shaken by what had just occurred.

"You can tell me how to steer from this point to the place where Dan found the under-water tunnel yesterday?"

"Aye, sir, that I can," repeated the sailor.

"Come here and take the wheel, then," said Mr. Craig, briskly.

"The wheel, sir?" ejaculated the Admiral. "By Joshua! I don't see no kind of a helm on this uncanny boat—that I don't."

"Come here and I'll show you as I did the boys," returned the inventor of the submarine craft, chuckling. "And there's the compass. You know the course, I am going to raise the submarine a trifle off the bottom—just a few feet—and we'll go ahead cautiously."

Again, with scarcely a jar, the wonderful boat was started forward. As they passed between the capes, the water-way seemed to grow darker. Perhaps, too, the channel was deeper.

The Admiral, with his bald brow all puckered into a frown—wrinkling his whole face indeed like a withered pear—stood leaning over the table watching the needle on the card and occasionally glancing ahead into the semi-transparent sea.

"It bothers you not to be able to see about you and get your bearings by actual sense of sight, eh?" asked Mr. Craig.

"It ain't like handling a craft on the top-blue of the sea—like Christians should," grumbled the Admiral.

"We'll fix that, then," said the inventor, smiling.

He stepped to a switch and lever far down in the metal bulkhead forward. There he stooped and swung back the creaking lever. From somewhere forward in the craft they heard the grating of metal against metal. Then Mr. Craig moved the switch.

A sudden glow suffused the water through which the submarine was slowly traveling. The boys, staring ahead with the Admiral, saw this strange light slowly permeate all their watery surroundings. A ledge, or huge boulder of rock, loomed unexpectedly on the starboard bow, and all three of the guests were simultaneously startled. It seemed as though the submarine had barely escaped a collision.

"I knew it was there," said Mr. Craig, drily. "You see, I have been in this channel before in the boat, and I believe I know the soundings even better than our very good friend, the Admiral."

"By Joshua I" grunted the sailor. "I believe ye do, sir. I never suspected that rock bein' here. If we'd bumped it——"

His voice trailed off into silence. Mr. Craig had touched the switch of the searchlight again and a ray of powerful illumination shot straight out from either side of the boat's nose, revealing clearly all that lay before the submarine for a hundred yards and more in advance.

"That's better," exclaimed the Admiral with more confidence. "Now a feller can see somethin'. I don't mind a-steerin' any boat if I kin use my own proper sight for it."

Along the bottom of the cove the submarine moved slowly, the old sailor studying the compass and looking about through the huge plate-glass windows with serious, puckered face. The searchlights showed him every ledge and boulder in the track, and the submarine went on without as much as rubbing her keel.

At last the Admiral muttered:

"About here, Cap'n. Here's where the Red Arrow lay when Dannie dived overboard."

Mr. Craig stopped the boat instantly, reversing the mechanism which propelled her a little so as to keep her hanging in position.

"Yonder's the reef betwixt which we sailed the Fannie Hendricks back in '76," declared the old seaman. "What did I tell ye? The litter of that avalanche just dropped a little betwixt them ledges. We could run this boat into that opening."

"And we'll do it," said Mr. Craig, confidently, starting the submarine forward once more.

The searchlights made the interior of the passage so clearly revealed that all four of the occupants of the submarine boat could see plainly what they were heading into. The debris that had fallen at the mouth of this narrow inlet into which the Fannie Hendricks was sailed so many years before, had been pretty well cleared away by the action of the tide. In great storms the current probably sucked out of this tunnel from the cave in the cliff back of the avalanche with such force that great boulders had been rolled away and deposited in deep water. At least, the submarine found no difficulty in nosing her way into the passage.

Its roof was twenty or thirty feet below tide mark. The height of the tunnel itself must have been sixty feet—a great, flat-roofed passage in which three vessels the size of Mr. Craig's invention might have sailed abreast.

It seemed to Dan and Billy, bearing in mind all that the Admiral had told them of the wreck and the circumstances surrounding it, that the old sailor had guessed just right when he explained the presence of the ledge of rock at the point where Colonel Sudds dug down for the treasure of emeralds. Without doubt, when the avalanche occurred, the face of the cliff, in one great, solid mass, had fallen across the reefs which now made the two walls of this marine tunnel.

This great mass of rock now roofed the cavity into which the submarine had pushed her nose. It upheld tons of the looser earth of that avalanche that had occurred in 1876. It had undoubtedly driven the sloop beneath the surface of the water and made her a wreck—and pinned her captain, Marksman, and his vase of emeralds, under it all.

The submarine was now her entire length into the passage. Dan Speedwell had certainly taken a great risk the day he dived and swam into this place to find the wreck, and had brought to the surface the single emerald that had doubtless been dropped by one of the fleeing crew when they left Marksman and the Fannie Hendricks to their fate.

Suddenly Mr. Craig seized a lever and stopped the forward course of the submarine boat. The Admiral, too, cried out:

"There she be! there she be! She's st'arn on and bad smashed, she is."

"The Fannie!" queried the excited Billy.

"It is the hull of a vessel for sure," declared Mr. Craig.

"It was her metal sheathing I touched when I came down here," stammered Dan. "Do you suppose I came in as far as this? My!"

"You certainly are some swimmer, lad," said the Admiral, with admiration.

They could see the hull of the wreck but dimly, for a huge boulder partly filled the passage. Indeed, it was quite evident that the submarine could not clear this obstruction.

"If it wasn't for that rock," Billy said, "we could hitch onto the wreck and tow her out with the submarine."

"I doubt it," Mr. Craig replied. "More likely, we'd tear the wreck all to pieces. She's settled badly into the mud and sand."

"Then we've found it, and yet we haven't found it," grumbled Billy.

"We will have to search her right here. We have a big job before us," said his brother.

"But she's here!" exclaimed the Admiral. "Are you lads satisfied that I've been giving you a straight tip?"

"We were satisfied before, Admiral," returned Dan, kindly. "But of course, we don't know that the emeralds are still in the wreck."

"You found one of them," said the sailor, stubbornly.

"That's right. But somebody may have found this opening and attacked the wreck before us," Mr. Craig said, quickly.

"I'd like to know who came into the Cove a while ago on the Midget," interposed Billy.

"We must look into that," agreed Mr. Craig.

The inventor was somewhat excited now. Perhaps he had but half believed the old sailor's yarn before. Now the wreck itself before them had clinched in his mind the belief that there was a possibility of getting the gems lost when the old craft was wrecked under the Slide.

"How will you get out of this place?" asked Billy, suddenly. "You can't turn around."

"We can back the submarine about as fast as we can drive her ahead," replied the inventor. "Now watch."

He reversed his propulsion pumps. The submarine drew back from dangerous proximity to the rock which more than half filled the passage. Mr. Craig turned off the searchlights in the bow, too.

The boys, turning to look astern, beheld the white, uncertain glow that announced the open cove. In a minute they were out of the tunnel—clear of it entirely. Overhead, however, was a good sized shadow.

"A boat is anchored here," Mr. Craig explained. "Close in to this side of the cove, too."

"It's that Midget!" exclaimed Billy.

"We'll rise in a minute—at least, we'll rise far enough to make sure. We need not show the submarine here in the cove so as to attract attention," spoke Mr. Craig.

"Secrecy! That's the word!" grumbled the old Admiral.

Billy pinched Dan's arm. "Isn't it great?" he whispered. "It beats all the treasure-hunting stories I ever read to just be acting out one!"

Dan chuckled. "Probably the Midget came down here with a party after black-fish," he said.

"Wait!" breathed his brother, as though the enemy was right at hand to hear them.

Out from under the roof of the tunnel and some cable lengths beyond the shadow of the anchored craft, the submarine was stopped by her inventor.

"Now, we'll go up," he said, quietly, and manipulated several levers.

A faint hissing noise followed and the boys saw bubbles rising through the water all about the glass house. The water was being discharged from the weight tanks. The submarine began to rise toward the surface, keeping as horizontal a keel as it had on sinking the first time.

As they went up the light became stronger. Soon they were able to see up through the water—out into the open air. Yet the roof of the conning tower was still not awash. Mr. Craig stopped the upward motion.

"That's the schooner!" cried Billy.

"It really is the Midget," agreed Dan, for they could see the craft anchored by the steep shore quite plainly.

"And by crickey!" ejaculated his brother, "if that isn't Chance Avery looking over the rail yonder, I'll never eat another supper!"

"It is Chance," agreed Dan.

"It is sure the young sculpin that come to try and pump me about the Dardanelle emeralds," said the Admiral.

"And what are those men doing on the shore?" queried Mr. Craig, who had looked beyond the schooner.

"They are digging into the bank. They have commenced an excavation about where Colonel Sudds fell down on the proposition; eh, Admiral?"

"That's jest as sure as shootin'," agreed the sailor, in a trembling voice.

"They are after the emeralds," declared Dan Speedwell. "It will be a race between them and us to see who will get into the old wreck first."

"Then, if that's the case, we've no time to fool away," cried Billy.

"None at all, gents," said the Admiral.

"I agree with you all," said Mr. Craig. "They're going at it from above. They doubtless mean to use explosives. If we are to go at it from below, we must get the diving apparatus and beat them out."

"A race it is," cried Billy, with delight. "We have raced Chance Avery many a time—and we've always beaten him out!"


XXI. — DAN IN DIVING TOGS

IN spite of Billy's expression of confidence, however, the quartette of treasure-seekers in the submarine were so sure of success that none of them wished to delay the attempt to get at the wreck where it lay in the submerged tunnel. Mr. Craig sank the boat a few yards—sufficiently far to escape collision with any ship's keel—and headed out of Rocky Cove at as high speed as the submarine could make.

He trusted Dan to govern the steering apparatus after they had passed the reefs at the mouth of the cove, and getting the course laid for Wild Man's Island, the inventor left the boys alone in the conning tower while he took the Admiral to the kitchen and set him to work getting a simple meal.

It was a wonderful experience for the Speedwell boys, although they were alone in the conning tower of the submarine for a few minutes only.

They were not far enough down below the surface of the sea to need the searchlights in the bow, for the day was bright and the sunlight penetrated the ocean for some distance. All about them was the pale green, white-streaked water. In it swam schools of small fish, with now and then a greater one; or a troop of big fellows swimming from one bank to another in search of food.

Mr. Craig soon came back and took charge in the conning tower. He brought the submarine to the entrance of the huge cavern on the island, and then rose to the surface of the sea. The hatch was opened just as the Admiral announced that supper was ready.

"We'll eat first and then get to work, boys," said the inventor, briskly. "We will turn night into day—that's where we will probably beat out the men digging through the Slide. It will not matter to us whether it is day or night, for we shall work under the sea."

"But we shall have to float some kind of a raft to work the air pumps on, and descend from," said Dan, quickly.

"No indeed. I told you the submarine carries a plentiful supply of compressed air. You felt no need of fresher air below; did you?"

"That is very true, sir," the older Speedwell said. "But how about getting down into the water in the diving suits?"

"Ah, my boy, I see what you're at," laughed the inventor. "We are going treasure hunting in a modern way. I had sometimes thought that if I perfected my submarine and could not interest the Government, I might turn attention to some of the famous wrecks strewn along both the Atlantic and Pacific coasts, and try and reimburse myself for my labor from their sunken coffers. There are millions of money strewn along the bottom of the sea, boys."

"And you mean that there is some way of getting out of this submarine onto the bottom of the sea, without descending in a diving suit from the surface?" cried Billy.

"That is what I mean, young man."

"It's like a diving bell," Dan declared.

"Only better. You shall see. Indeed, Dan, may try it first. We have but one diving suit. If we can accomplish our purpose without hiring an experienced diver, or getting other help, you boys will have to do the actual searching for the treasure."

"Bully!" ejaculated the younger lad.

"This old sailor is not fit to make the attempt, and I cannot leave the boat while she is under water. Are you afraid to try it, Dan?"

"I don't know, sir," said the older Speedwell, seriously. "I'll have to try it first to learn whether there is anything to fear."

"Good! Now let us eat. Then there are some preparations here to make. I will send a wireless to your folks, if you like, too, so that they will not be worried about you. We should be able to get under way for Rocky Cove again by midnight."

Dan and Billy knew that their parents would not be anxious about them as yet; nevertheless they were glad to be able to send home a word of cheer at this time. Both lads followed the inventor to the wireless station.

"This rigging was somewhat disarranged by the explosion the other day; but Fred Gedney fixed it for me and I have both sent and received all right. We'll see if we can call Rickett's," observed Mr. Craig.

He sat down at the table, put on the receivers and began tapping the key for the nearest wireless station. As the sparks crashed, their violet rays almost dazzling them, the Speedwell boys waited to see the message sent. But the moment he "got" Rickett's Dan knew that Mr. Craig was receiving instead of sending a message. In five minutes the inventor tore off his "earlaps" and shook the message before the wondering boys' eyes.

"What do you think of that?" he cried, with more excitement than he usually showed. "It's all over Riverdale, so your friend Blizzard, of the Star, says."

Dan read the transcript of what Mr. Craig had received. The message said:

"Schooner Midget sailed for Rocky Cove with dynamite and electric battery aboard. Reported in town that Mr. Francis Avery is to try to blow the way into a treasure vault under the Slide. The emerald has started all manner of rumors; but the Averys mean business.—J. Speedwell."


It was from the boys' father and Dan and Billy—as well as Mr. Craig—knew that the information must be correct or Mr. Speedwell would not have sent the message through the Star office and the wireless operator at Rickett's.

"What shall I say, boys?" demanded Mr. Craig.

"Just ask them to let Wiley Moyle run out to father's and tell him we are all right," said Billy, quickly.

"And that we have received his message," added Dan.

The inventor nodded, and turning again to the instrument, obeyed the request of the Speedwell boys.

Then they wended their way back to the workshop and the pool in the cavern where the submarine lay. There was, as Mr. Craig said, much to do. The diving apparatus had to be unpacked and overhauled. The inventor examined every inch of the suit and of the airpipe especially for any break or weak spot.

"When a man goes down under water in a rig of this kind," he said, gravely, "there is only a thin sheet of rubber betwixt him and a sudden and awful death. That rubber must be flawless."

As he went over the apparatus he explained it all to the Speedwells until both Dan and Billy felt assured that they would know just what to do in almost any emergency while at the bottom of the sea in the diving suit, or engaged in governing the air-feed pipe and the signal lines.

The suit and all seemed in perfect condition. Dan and Billy did not yet understand how the matter was to be worked from inside the submarine; but Mr. Craig did not explain that part of his plans to them.

They put the apparatus aboard. The pumps had been going during this time and the indicators showed that the tanks were well supplied with air and kerosene. The mechanism of the submarine was working perfectly in every part as well. With the Admiral, who had been busy all this time cooking, they entered the boat and started for Rocky Cove again.

This time they kept on the surface of the sea. As the craft swept out of the cavern the boys were astonished to find that it was already night.

They had lost track of the time there in the cavern.

An arch of star-flecked sky was over them. The sea was calm. In the distance the twinkling lights of several craft drifted between the sea and sky. On the point blazed the lighthouse, while the lesser beacon on the south claw of the cove entrance sparkled radiantly.

It was a perfect night—warm, and peaceful. Yet the boys, and their friends on the submarine, were going into grave peril, and were about to venture upon a course that would have made the sturdiest person shrink and hesitate.

The spirits and high courage of Dan and Billy Speedwell, however, were kept up by their excitement. It really was a race for the treasure of emeralds, as Dan had suggested. The Avery brothers were bent upon trying to get through the mass of earth and rock that had fallen on the Fannie Hendricks, while those in the submarine were attacking the problem from an entirely different direction and by different methods.

The submarine raced across the open sea to the entrance of the cove. There was not even a wandering fishing smack, or a coasting schooner, to cross her path. If the glow of light in her conning tower was seen from the lamp ashore, or from the life saving station on the other point, it was probable that the 'longshore men, used to viewing the sea with most practical eye, thought the drifting and uncertain light to be phosphorescent.

Once in the strait between the crab-claws, however, Dan cried:

"They're at work! See yonder?"

Flaring gasoline torches lit up the deck of the Midget where she lay before the Slide, and likewise a space of open ground upon the shore itself.

"Why, those fellows are digging by lamplight," murmured Mr. Craig.

"That's the way to hunt for pirate gold," chuckled Billy.

"The swabs!" growled the old Admiral. "They don't let no grass grow under their feet, do they?"

"Nor will we," rejoined Mr. Craig, grimly. "Now, boys, we'll drop below. Say good-bye to the open world—to the sky and air. If we have any luck at all, before you see either again, we shall know all about the secret of the buried wreck."

"Do you mean it, Mr. Craig?" gasped Billy.

"I do. Let them go on with their excavating. We'll get to the wreck and satisfy ourselves one way or the other before those fellows can blow a hole down to her."

He spoke eagerly and with confidence. Al-ready he was sinking the submarine. The glass house finally disappeared beneath the surface. They sunk to within a few yards of the bottom. The searchlights were turned on and straight as a dart the submarine shot into the tunnel under the mound of debris that had lain so many, many years over the wreck of the Fannie Hendricks.

They ran in until the submarine lay near that huge boulder that half blocked the passage and made it necessary for the craft to halt. There the wonderful boat settled down upon the sand of the bottom.

Mr. Craig had already laid out the diving suit in one of the forward compartments. He had the air tube fastened to a small pump which, in turn, was connected with one of the air tanks of the boat. Giving Dan for a second time plain instructions how to act and what to do in certain emergencies, the inventor, with Billy's help, got Dan into the suit.

The weighted shoes of the dress clogged Dan's movements, but he knew that once in the water the weight would not trouble him. The suit was drawn up to his shoulders and he slipped in his arms. Then the heavy helmet was put on and the inventor fastened it in place. For a few moments Dan felt stifled. Then a cool current of air began to play into the sealed helmet. He could breathe easily.

He stood up. Mr. Craig took his hand and motioned him forward. Dan knew that, by some mysterious means, he was about to be put outside the submarine. But how could that be done, down here at the bottom of the sea, without letting the water pour into the craft and effectually flood it so that none of them would ever be able to rise to the surface again?


XXII. — FACE TO FACE WITH DEATH

DAN SPEEDWELL realized that they had reached a door in the bulkhead which required some manipulation on the part of Mr. Craig, the inventor of the submarine, to open. Finally it sprang back and they passed into a dark apartment that Dan knew (as soon as the light was flashed on) was situated next the outer shell of the craft, for the side and ceiling of the room were curved.

Mr. Craig wrote something on his notebook and held it before Dan's eyes. The lad read these words:

"I am about to seal you up in this room. Then I shall open the cocks and let in the water. When the compartment is full, turn the handle which I will show you and the hatch will open, giving you egress. I rigged the iron ladder to the outside of the hull before we left the island. You can descend to the bottom in safety, and on returning, reverse the order—shut the hatch and I will pump out the water from this place. We shall watch you from the conning tower. God bless you!"

Dan nodded. Mr. Craig showed him the peculiar knob that he was to turn. Then the inventor shook his hand and left him in the room. They boy felt very queer indeed. Not exactly frightened—for, as he had said, he was not sure there was anything to be frightened about in thus going into the open sea in a diver's armor. Dan was a boy who always waited to be sure there was peril before he trembled.

The long hose carrying the air was coiled neatly at his feet. The signal line tied to his left Wrist was in the clear, too. By means of watertight valves these two lines of service, which attached him to his friends, were carried through the solid bulkhead of this diving room and Dan knew that they would be carefully tended by his brother and Mr. Craig.

Into his right hand the inventor had thrust a large and powerful storage battery lamp; but this would not be called for unless he succeeded in getting within the hull of the wreck itself. The submarine's searchlights would give the youthful diver all the illumination he would need upon the bottom of the tunnel.

Into his belt was thrust a short, sharply hooked rod—a rod something like an elephant goad. It is practically the only weapon, or tool, the diver needs—unless he is going down in tropical waters where the man-eating sharks abound. Then he carries a long, two edged knife with him.

But Dan Speedwell had no such peril as this to apprehend. He knew that the hook had been given him for the tearing away of rotten wood, or the forcing open of a door, should he be fortunate enough as to get aboard the wreck of the Fannie Hendricks.

Suddenly Dan was aware of something new in the compartment into which he was sealed. The air still reached him nicely, but his feet and ankles—indeed his legs half-way to his knees—were becoming strangely cold.

At the moment, too, the electric bulb behind him was darkened—the light was suddenly quenched. He had a sort of shivery feeling, standing there in the dark—and the chill was rising up his body with a rapidity that half frightened him.

Then he remembered his lamp, and pressed the spring. The spot-light flashed out, and he naturally turned it downwards. Water was rippling about his knees as he stood there on the metal deck—and it was rapidly rising.

"He's opened the cocks as he said," thought Dan, feeling sudden and great relief. "And I'm to turn that knob and open the side of the ship when the water rises over my head."

He knew that as the water rose the air above in the chamber must be compressed greatly; but he did not know that this air was being sucked out by a pump arrangement and that was why the water entering through the sea-cocks rose so freely.

In five minutes the water lapped the bulging glass windows of his helmet. He could have been no more sealed from the outside air than he was before the sea rose over him; nevertheless it gave him a strange feeling when the water was entirely above his head.

Its chill was communicated through the rubber suit to his body; but now it was a pleasant coolness, for the rubber dress stopped respiration to a great degree.

Knowing that the time had now come for him to act, Dan laid hold of the knob with both hands, after putting the lamp into a socket in his belt. It turned with difficulty, and the weight of the water about him, and the weight of the diving dress, both made it harder for the lad.

He unlatched the fastening, however, and was able to slide back the door in the outer sheath of the ship. There was an eddy about him in the water for a moment, and that was all. He poked his head out of the opening and shot the ray of the hand lamp downward.

There was the iron ladder Mr. Craig had mentioned. Dan dragged his leaded feet through the opening and stepped cautiously down the rungs. The deeper he went down, the lighter the dress he wore appeared to he, until, when he stood firmly upon the bottom of the sea, with the pipe and signal line trailing behind him, he found himself able to step out from the submarine's hull with much better ease and grace than he had expected.

He looked upward at her shining side. He had had no idea before that Mr. Craig's invention would seem so huge and unwieldy in the sea.

Ahead the illumination of the searchlights showed him the way to the wreck. He could even see the outline of its stern looming up, around the great mass of rock that half filled the submerged tunnel.

When he was out from under the shadow of the hull the headlights played about him. Dan turned slowly and looked back. High in the dimly illuminated glass tower he could see three shadows—no more. Although the inventor, Billy and the Admiral could see him clearly—see every move he made and how it went with him—their figures were vague to Dan, and their features quite unrecognizable.

The lad spent little time in contemplating these things—or in looking at his friends. He was excited over the work before him—he wanted if possible to get into the wreck and find out all about it.

To search the sea-bottom for the scattered gems the deserting crew of the sloop had let fall as they escaped just before the avalanche, would be a task indeed. The Admiral's story of Marksman left in his cabin with the vase of jewels before him on the table, had been impressed clearly upon Dan's mind.

Had the captain of the Fannie Hendricks remained right there until the avalanche fell, beating his craft down under the water and drowning him? Or had he found time to hide the vase of emeralds somewhere, and would his skeleton be found in some other part of the ship?

The Admiral had always spoken of the vase and Marksman in the attitude he had last seen them; but Dan knew that the matter of finding the jewels might be a much more difficult thing than the tale suggested.

However, he should know soon. Here was the stern of the old sloop, its broken rudder chains eaten to shreds of rust, its woodwork so rotten that with the hook in his hand he could easily tear away great masses of the wood above the copper sheathing.

The wreck lay partly canted over to port. The rail around there was not out of reach of his hands. He seized the wooden hand-hold and it crumbled away in his clutch. But he found, when he essayed a second attempt, that the deck boards of the vessel were sound. Some woods keep for years under water; others more easily rot and mould away.

The young diver crept up on the slanting deck and made for the deckhouse. The searchlights of the submarine gave him very little illumination here; but his own hand lamp helped a good deal. He saw the forecastle hatch, wide open and the water flowing through it from a great rent in the bows of the wreck. A lazy fish rose with a single wriggle of his powerful tail, from the dark depths of this hold, and sailed serenely toward the boy in the diver's dress.

Dan stood there motionless while the creature came close, its goggle-eyes peering into the window of the boy's helmet. Then the fish shot away, leaving a trail of bubbles behind it.

It seemed like stepping into a long abandoned dwelling and being met by a stray cat!

Dan, however, spent little time waiting on the deck of the wreck. He was as courageous as the next youth. He had faced the perils of this under-sea experience without a qualm. Now, before him, he expected was a scene of dreadful death.

In all probability the Admiral's tale of the wreck was true. Marksman had met his end in the cabin of the sloop—all that was left of his body was down there now.

And Dan Speedwell had to go down into the depths of the cabin and meet this ghost of the past. Either that, or he must give up his attempt to find the vase of emeralds.


XXIII. — SUCCESS—AND FAILURE

DAN SPEEDWELL felt no tinge of weariness, however, as he stood on the deck of the sunken wreck. Hesitancy he did feel—perhaps the gruesomeness of the task before him could excuse that. He had to go down into that cabin. And what horror might he not find there?

At length, however—even before the trail of bubbles left by the startled fish had disappeared—Dan stepped up the deck to the closed door of the cabin.

"And if we are going to get the emeralds we are searching for, that cabin must be entered," thought Dan, grimly. "I might as well go in the place first as last. I'm no better than the others."

Dan tried the door of the cabin. He could not shake it; but it was a sliding door and he managed to get the point of his hook into the crack between the door and the frame. With some difficulty he forced it back, an inch at a time, but finally far enough to enable him to thrust his helmeted head into the opening. Naturally the hand lamp was thrust in, too. Dan turned the ray first in one direction, then in another.

Down the companionway into the cabin the boy finally stumbled. He believed he could not go much farther, for he was almost at the end of the airpipe and line. To work in the interior of the wreck he would have to burst a way in from the stern, which was so much nearer the submarine.

Now, however, he was mainly anxious to discover what there was in the cabin. The water filling the apartment was as black as that of a peat-bog. Indeed, there was a sediment of mud and rotted wood upon the deck he trod upon at the foot of the companionway stairs.

The electric lamp seemed feeble in this place. First Dan made out the fact that the cabin table still stood in place. It was, of course, screwed down. But it was bare. There was no vase of emeralds upon it.

Dan took a step forward. Something bumped his shoulder and he turned with some fear to look. A chair floated about in the water, bumping against the deck above. Yonder was another. There were other objects that, in all these years, had not become water-logged. His opening the door and stepping down into the cabin had started them all to swaying.

It must be confessed that Dan looked about for the uncanny thing he had expected from the first to find. But it was not there. He went around the table—to the farthest limit of his air-pipe—and found nothing of the kind. Whatever had become of Marksman—his corpse, or his skeleton, was not in this cabin.

Nor were the emeralds. At least, that was Dan's opinion at first. He had expected them—in some degree, at least—to be in the vase on the table for the first eager hand to grasp them.

Then he remembered that at the time of the wreck—when the avalanche had descended upon the place where the Fannie Hendricks was anchored—the boat must have been driven to the bottom of the inlet with terrific force—and with great suddenness as well.

Here she lay—and had lain ever since that time—on her port beam-ends, filled with water and with every movable thing in her swashing about with the tides. If the vase had really stood on the table at the moment of the catastrophe, it had not stood there the moment after.

There the table stood. Dan had difficulty in getting around in the compartment, the deck was pitched so sharply. What lay scattered in the sticky mud on this floor?

The thought struck Dan so forcibly that, for a minute or two, he could not move. He thought, meanwhile, just what move he should next proceed to make.

If the wreck sank on its side as it now lay, the vase of emeralds would have fallen from the table toward the lowest point of the slanting floor. He got down there slowly and lowered himself to his knees. Stiffly he began to feel over the silt on the deck with his gauntleted hand.

Suddenly he picked up an object which, for an instant, puzzled him. It was a rough piece of broken china, or clay-ware. A broken dish——

"The vase!" Dan thought, with a sudden flash of inspiration. He felt about the deck again with his free hand, holding the light so that it might reveal what he found.

What were these hard substances under his hand? Were they pebbles, or bits of the shattered vase?

He seized one between thumb and finger and held it in the glare of the electric torch. It was dark, and hard, and uneven in shape. Dan could not see it clearly, but he felt sure that it was an emerald.

He scrambled about some more. He found several others. Soon he had a handful.

And then the question came to his throbbing brain: What should he do with them? Where could he put them while he gathered other handfuls of the gems—if they were here?

The young diver suddenly found himself trying to put the handful into a pocket. But there was no pocket he could get at. There was absolutely nothing in which he could carry the gems.

It had been in his mind that, if the emeralds were here at all, they would be in the vase and he would be able to clasp an arm about the vase and carry it to the submarine with him—never thinking of the weight of what the Admiral called "a bucket of emeralds."

Now, as it turned out, his short-sightedness had left him without other alternative than to go back to his friends with but a poor handful of the gems. He felt sure the great wealth of treasure the Admiral had promised was here; but he could not take it away with him.

"I've got to go back," thought Dan. "I must bring a bag—or somebody must come here with a bag."

He suddenly realized that he was very weary. The excitement and uncertainty had until now kept him up. The weight of the dress was great, however; and muscular exertion under the sea is vastly tiring.

He stood up, uncoiled the pipe and line from about the table and went back to the companion-way and so up to the deck. He clung to the emeralds he had picked up, however; this made his movements more uncertain. He had great difficulty in getting off the wreck and around into the blinding glare of the submarine's headlights.

Dan was aware that his appearance was wildly hailed by the frantic gyrations of one of the three shadows up there in the glass cage. That must be Billy, he told himself. It was possible that Billy—and the others—had become worried by his absence.

But not until he had gone inside the diving chamber of the submarine, had shut the door, locked it, the water had been drained out and he was in the hands of his excited friends and the helmet was unscrewed, did Dan Speedwell for a moment guess that he had been away from the submarine for more than three hours.

"And they're emeralds—like the other he found, only smaller!" were the first words Dan heard as the helmet came off. Billy had emptied his brother's hand into his own and he and the Admiral were staring at the discolored jewels Dan had brought away from the wreck with him.

"Oh, Dannie!" cried Billy. "Where's the vase? Why didn't you bring them all?"

"Hoorah!" rumbled the Admiral, his gray hair standing up all around his bald spot like quills. "I was right, wasn't I, boys? Did you find the emeralds jest as I told ye, lad? And Marksman?"

"Thank heaven I did not find your old captain," returned Dan, sitting down wearily. "I do not Know what has become of the poor man. And the vase is broken and the gems scattered all about the cabin floor. I had nothing to bring them away in——"

"My oversight," said Mr. Craig, now examining the emeralds. "I should have given you a pouch, or apron, which goes with the suit. It is here. Now, these emeralds are all right. Why, boys, if there are many more as fine as these we are all well paid for this venture."

Hardly had he spoken these words when they were all aware of a muffled crash—a sound that, sealed up as they were in the submarine, must have reached their ears from without. The boat trembled, too, and all the pointers and little arrows on the dials in front of Mr. Craig vibrated.

Without reason, yet in unison, the four in the submarine turned to look astern through the glass plates. There was but a mass of dusky water toward the mouth of the tunnel into which they had penetrated. At least, they could see nothing more.

"What do you suppose has happened?" whispered Billy, awestruck.

Mr. Craig suddenly began to bestir himself. He shut off the forward searchlight and proved, in another moment, that the submarine was well prepared for every imaginable emergency. There were lights in the stern, too, and these were quickly adjusted and the slides—like eyelids—slipped off their glasses.

Two sharp rays cut the gloom to the rear. The water was much agitated and for some moments the searchlights revealed little to the anxious quartette in the conning tower.

Then Billy Speedwell uttered a sharp cry. The Admiral fairly yelled. But Dan and Mr. Craig were silent. They both were cautious; they both wished to make sure before speaking.

But there could be no mistake. Some great mass filled the tunnel—or seemed to fill it. The mouth of the submerged passage into which the boat had been driven was stopped up!

"Caught like rats in a trap!" cried Billy. "Don't you see? Those fellows up above have been using dynamite."

"So quickly?" breathed Mr. Craig. "It—it isn't possible."

"Aye, aye; but it is so," rumbled the Admiral, mopping his head in excitement. "What'll we do now? The hole we got into is stopped up. There's been another shifting of the rocks and gravel, by Joshua!"

Dan Speedwell said nothing. He appreciated their position quite as keenly as the others. They were trapped in the submarine and the submarine was trapped in the tunnel under the Slide.


XXIV. — A DESPERATE SITUATION

THE astonishment of all four of the crew of the submarine was greater than their apprehension. They did not altogether realize—not even Dan Speedwell—what the dynamite explosion above had done for them. Indeed, no human mind could—in a single moment—understand all that the choked-up tunnel meant.

"How about beating Chance Avery now, Billy?" was Dan's grim remark.

"It—it doesn't look so sure," stammered the younger lad.

"Nor is he aware that he is doing us any harm," cried Mr. Craig. "And let us wait; we do not know yet that he has particularly hurt us."

But his encouraging words were lost on the others. They saw no possible way of getting out of the difficulty. Mr. Craig, however, was peering with anxious scrutiny at the uncertain wall not many yards beyond the submarine's stern.

"Come!" he exclaimed. "We must not lose heart. And only think—with the emeralds actually in our grasp! I believe something can be done with that mass back there."

"How will you do it from here?" asked Dan, bluntly.

"Boys, this submarine is built for rough work. It is no plaything," said Craig, gravely. "It is a fighting machine. If it could not ram an ironclad as well as throw torpedoes, it would not have been looked at twice by the Navy Department."

"Ram—do you mean we can batter our way out of this hole?" cried Billy.

"I mean we'll try it," said the inventor.

"But this glass cage——"

"Quite so," said Mr. Craig, nodding. "It would be knocked to flinders, eh?"

"Yes, indeed!" cried Dan and Billy together.

"I expect you are right there," said the inventor, wagging his head. "But we cannot help that. It will have to go. We will merely close this deck hatch and put the submarine on a war footing. We'll have to lose the conning tower, I expect. But not yet."

"Not yet?" repeated Dan, puzzled.

"We must not be too precipitate. The tunnel is choked up. We cannot help that. It will not become worse by waiting a while."

"But how long will our air hold out, sir?" asked Billy.

"For ten hours yet," returned Mr. Craig, briskly. "Meanwhile, as we are down here, would it not be best to finish our task first?"

"Get the emeralds, do you mean, Mr. Craig?" asked Dan, in astonishment.

"Yes. Let me tell you, boys, that if we have to butt our way out of here—as it seems we will—there will be no coming back. And we can butt our way out two hours hence as well as we can now."

"Lemme get into them rubber contraptions," said the Admiral, suddenly. "I'll try my hand at it."

"No," said Billy. "It's my turn."

Dan felt himself refreshed by now—bodily, at least. And he was encouraged by Mr. Craig's determination and coolness, too.

"I know just how to find the cabin and how to get into it," he explained. "I am not afraid that I shall not find the emeralds, either. I will get into the dress again."

"It is suitable, I believe, that Dan should try again," agreed the inventor. "It will save time, The dress fits him. Let us be at it."

The Admiral had had a hot drink and a sandwich ready for Dan when he had returned from his first trip to the wreck. But it was now past sunrise and they all ate a hasty breakfast. No light showed at the choked mouth of the tunnel, however. To all but Mr. Craig, at least, the situation looked desperate.

Around Dan's waist, after he was dressed, the inventor buckled a pouch and with this and the lamp the youth set out from the diving chamber after the latter had been filled with water and the slide was opened.

He found no difficulty in getting into the interior of the wreck. But all the time he felt very badly indeed about their position down there in the tunnel.

The emeralds he was groping for on the deck of the cabin seemed paltry things just now. Dan wondered why he had ever come into the wreck for a second time after them.

"What's wealth to life?" was the question that continued to run in his mind.

He would rather have seen his mother, and Carrie, and little 'Dolph—and Mildred Kent and the other girls and boys in Riverdale—than all the emeralds ever mined.

Mr. Craig had assured them that a little delay made no difference. The inventor seemed quite confident of getting out of the tunnel by ramming through the wall of debris that had fallen because of the blast above. But suppose there should be a second explosion of dynamite?

All the time Dan was scrambling for the emeralds. He never could tell if he got anywhere near all of the gems. But he dug up out of the slime handful after handful, until his pouch felt quite heavy.

His fears did not make him unfaithful to the task set him. His weariness grew so great at last, however, that he was afraid to search longer. He might not have the strength to get back to the submarine.

Indeed, when he climbed the iron ladder to the diving chamber, he could barely drag one lead-shod foot after the other. He was so exhausted that he could not stand when the dress was removed by his brother and the Admiral.

"A peck of emeralds—as sure as I live there's a peck!" Billy was saying, over and over again. "Why, when we get out of here we'll be as rich as the Darringfords—or as Dr. Kent!"

"When we get out of here—yes," murmured Dan, weakly.

"Wake up, old boy!" cried Billy. "Mr. Craig's going to shut the submarine up as tight as a drum and we'll go through that wall to the rear like a bullet through plaster!"

Billy had recovered his good spirits, and even the Admiral seemed inspired with renewed courage. Dan could see that the inventor's assumed confidence had influenced both.

Dan determined not to be a wet blanket—in other words not to cause Billy or the old sailor to lose confidence in Mr. Craig. But he was depressed and deeply worried himself—nor could he shake this apprehension off.

The bag of emeralds did not shake him out of his lethargy. Billy's ecstasies, nor the Admiral's and Mr. Craig's more quiet satisfaction, did not impress Dan. What were thousands of dollars' worth of emeralds to them, if they were caught down under the water here?

He paid little attention while he sat there, recovering from the strain of the last hour, to what was going on in the submarine. But it was Billy who came to him with the announcement that Mr. Craig had cast loose the glass conning tower and closed the upper deck of the submarine, sealing it effectually against the sea.

"And he is going to govern the machine now just by what those funny instruments tell him. The Admiral is scared blue, I can see," chuckled the boy, "because he can't see about the ship."

Suddenly they felt that the submarine was lifting. She was off the ground and Mr. Craig seemed to be driving her ahead. But she could only move a few yards farther up the tunnel toward the wreck. He wanted, however, to take what Billy called "a running jump" at the obstruction in the mouth of the passage.

Suddenly the propulsion pumps were reversed. The heavy engines throbbed so that they shook the submarine from bow to stern. She drove backward with terrific force and when she collided with the wall of rock and debris that had fallen since the dynamite explosion it seemed as though she would be wracked to pieces.

The power of her blow was tremendous. The pointed stern of the submarine penetrated the loose mass and it seemed as though she would get through it all and out into clear water beyond.

But suddenly she stopped. Her engines could drive her no farther.

Mr. Craig drew her back and the blow was repeated; but with no better success. Again and again the submarine was propelled at the wall of debris, with no appreciable result.

They were indeed entrapped down here under the sea. Their supply of air must give out ere many hours passed. Their friends could not be sure of their situation; and even had anybody known of their presence under the Slide at Rocky Cove, what could human ingenuity do toward releasing them?


XXV. — UNEXPECTED DELIVERY

THE trembling of the submarine ceased. The engines were stopped. Dan and Billy, with their old friend, the Admiral, knew well enough that the inventor had come to the end of his resources. The wonderful craft was tightly housed up in this tunnel and as far as their powers went, there was no escape.

Mr. Craig came out of the place which once had been the lower section of the conning tower. He was heated and dejected. He had taken off his coat and vest (indeed, it was noticeably warmer in the submarine now, and the air seemed harder to breathe) and the damp hair hung on his forehead, stringlike. The Speedwell boys had never seen him so distraught before.

"Useless, useless," he groaned. "We are trapped. Boys, I fear I have recklessly brought you to your deaths!"

"But we got them emeralds. Cheer up, messmates!" croaked the old Admiral. "Never say die. Dick Billings has been in tight corners afore!"

"Well, let Dick Billings find a way out of this one!" snapped Dan, worried to see the inventor give up hope.

"Looking for ways out ain't in my line," returned the sailor. "But there won't no chance for gettin' out escape me—you can bank on that, my lads!"

As he spoke the submarine trembled again. They looked at Mr. Craig, who stood up quickly.

"No!" he exclaimed. "All machinery is shut off. We are lying motionless——"

The vibration continued and there seemed to be the same sound they had heard before when the dynamite charge exploded.

"It's another!" cried Billy, under his breath.

"It will bury us deeper than ever," groaned his brother.

"But we don't know that," exclaimed Mr. Craig, and like a flash he was in the controlling chamber again. He manipulated one lever after another. The submarine went back, trembled for a moment, and then was dashed forward against the chaotic jumble of rubbish at the mouth of the tunnel.

They all felt the shock of the collision; but the submarine kept right on.

It seemed to the four crouching within the metal walls of the wonderful boat that she must split on the rocks with which she collided. They expected the water to rush in and overwhelm them at any moment. It seemed impossible that she really could dash through the debris.

Still she kept on, and her speed increased. The submarine for those few uncertain seconds seemed to run at a mad pace.

Suddenly the jarring and jolting ceased. They went on smoothly. Mr. Craig bent over his indicators, stared at them for a brief moment, and then uttered a cry of gladness.

"We're out! we're out!" he said. "We're out in the cove!"

He touched another lever, and while still at full speed the boat tipped upward toward the bow, and in a few moments they were at the surface.

Instantly he went to the fastenings of the small hatch by which they had entered the boat, and the boys, staggering after him, were almost at once met by a blast of cool, sweet air and a flood of sunshine.

Never did the out-door air and the sun itself seem so fine before. The old Admiral followed them and all stood under the open hatch and clasped hands.

"Thank God for that!" murmured Mr. Craig. "It was miraculous. The very thing that buried us in that place, set us free. That second discharge shook the rubbish loose at the mouth of the hole."

Billy suddenly smote his brother on the back. "Wake up, old boy!" he said. "Wake up, Dannie! We've got the emeralds! The lost treasure of Rocky Cove is ours!"


But it was some weeks later ere the treasure-seekers knew just what they had found—or what Dan Speedwell had found, to be more exact—in the wreck of the Fannie Hendricks. Divided as it had been agreed, however, the treasure of emeralds, on being sold in New York, gave the Speedwell boys more than twenty thousand dollars.

They were rich—in the eyes of their friends of Riverdale, especially of their school friends, Dan and Billy were very rich indeed.

The Speedwell boys were not likely to waste this fortune, however. Their father, under Mr. Craig's advice, invested it rightly. Some, however, Dan and Billy had the pleasure of immediately spending. And they obtained for their parents and for Carrie and little Adolph many luxuries that had been denied them before.

Mr. Speedwell's dairy was enlarged, too; a regular electric truck was bought with which to deliver the milk. And the boys could now look forward as a surety to a technical college course, for both Dan and Billy were determined to become finished mechanics and engineers.

Francis and Chance Avery stopped spending their money excavating in the Slide at Rocky Cove after they heard of the Speedwells' good fortune. And it was not long ere they left Riverdale altogether. The Darringford Machine Shop lost its superintendent, and few there were in Riverdale sorry to see the Avery brothers go.

Mr. Craig repaired his submarine and, later, sold the invention to the Government. He and his cousin, Mr. Gedney, are understood to be in partnership now in the building of a much more wonderful machine than was the submarine boat, but they are so secret about it that even Dan and Billy do not know its nature.

Of their friends who congratulated the Speedwell boys on their good fortune, none did so more warmly than Mildred Kent and Lettie Parker. The girls and the Speedwells often run down the shell road toward Barnegat and stop to "visit" with the Admiral in his snug red cottage overlooking the bay. The securing of ample means for the old sailor's use did not change him in the least, however. The little red house and the flagstaff and the brass cannon are the dearest things in the world to the Admiral, and he sticks to them.

As for Dan and Billy, their good fortune did them no harm. Guided by wise parents they will undoubtedly put all their fortune to good use as the years go by. Meantime we will leave them to complete their summer vacation, crowding into it all the fun and healthy enjoyment it will contain, and with the help of their motorcycles, their racing auto, and their power launch, they should—with their friends—pass a delightful vacation indeed.


"Say, going under the water was some stunt, wasn't it?" remarked Billy, one day, when he and his brother were out for a spin on their motorcycles.

"It certainly was," answered Dan. And here let us say good-bye to the boys and leave them.


THE END



AFTER the summer vacation, winter would come, and if you wish to learn what then happened to the Speedwell boys you will have to read the next volume of this series, to be entitled: "The Speedwell Boys and Their Ice Racer; Or, The Perils of a Great Blizzard." In that we shall meet all our young friends once more, in adventures just as strenuous as those already encountered.


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