"th' signal book! get the signal book!" bawled greer amid the uproar.

"w'ere is it?"

"in the flag locker! chuck the flags out, too! scatter 'em out!"

"w'ot you want to signal?"

"submarine—tell 'em to look out for submarines!"

hogan, who held the volume in the crook of his bandaged arm, licked his thumb and jabbed through the leaves in distracted attention. "there aren't no code letters for submarine!" he cried at last—"not in here!"

"no," shouted black, the vulcan's former captain, "that's an old code—wasn't any submarines then!"

"spell it out!" commanded caradoc from the bridge. "sharp about it!"

the men worked in a clutter of buntings, assembling the flags in nervous haste. black laid out the nine letters and the crew hurriedly hooked them together. ten minutes later, they strung the signal between the two splintered masts with a queer drunken gala effect.

the vulcan was no longer the german squadron's sole target. down on the teuton battle line thundered five english cruisers, filling the north with rolling smoke, their turrets spangled with cannon flashes, prows shearing white walls of foam.

the sky above the vulcan was filled with the drone of hurtling shells. they sounded as thick as swarming bees. the cannon fire of the approaching english ships mounted to a ragged roar. when the on-coming line was less than five miles distant, caradoc shouted an order to galton and the little tug swung around broadside on, displaying her warning signal like a billboard. through the battle smoke, madden saw an answering flag go up on the nearest ship. a cheer broke out from the crew at this recognition of their work.

"they'll pass it around among the fleet by wireless!" shouted caradoc in madden's ear.

"do you know that ship, smith?" called madden excitedly.

"the panther—held a commission on her once."

"is it possible?" madden peered at her through his glasses with renewed scrutiny.

they were so close now that the american could pick out the crew of range finders working in the fighting tops; he could glimpse the huge guns in the forward turrets as they flashed and roared amid shrouds of smokeless powder haze. madden realized he was seeing what every landsman dreams of seeing: a naval battle. for some inscrutable reason, caradoc had headed the vulcan clear around and now faced the enemy, like a rat terrier amid a battle of mastiffs.

madden turned aft as the tug swung around to follow the fortunes of the panther. he could see german shells exploding now and then on her decks; sometimes they would strike the sea and send up typhoons of water and weed. as he gazed a small-calibre gun was struck, and there was nothing but a ragged smoking hole where the port had been. an instant later, the mizzen top was shrouded in an emerald flame, and when the smoke cleared, only a jagged stump of iron thrust skyward. the crew of range finders had been wiped out in an instant. several hours later, leonard learned that the whole german gunfire had been focussed for several minutes on the panther.

but now that gray, smoke-wreathed cruiser rushed on indomitably, flanked by her thundering consorts. the half-naked men on the panther's decks looked curiously small in their huge rushing fortress. german shells battered her decks amid spangling green flames but could not stop her. as she overtook the vulcan, the concussion of cannon fire and bursting shells grew so terrific it ceased to be noise. it resolved itself into blows, terrific air movements that smote madden all over. it pounded his ear drums with physical blows; it tore at the bridge of his nose, jarred his teeth, sent shooting pains through his head, for he was not wise enough to stuff his ears with cotton and hold his mouth open. it shook the pit of his stomach and nauseated him. it was a sound cyclone. added to this the sickening acrid smell of niter explosives filled the atmosphere.

on came the panther through the green foam of german fire, mingling the mighty vibrations of her engines, the hiss of leaping walls of water, tempests of cannon fire and vindictive shriek of leaping shells.

caradoc leaned over to madden and yelled something at the top of his voice. madden shook his head as a signal that he could not hear. smith repeated so loudly that his long face grew red with the strain. it was impossible to catch a word. besides, leonard's ears ached as if the drums were ruptured.

caradoc caught up a speaking trumpet and held it to his friend's ear.

"don't look at the panther!" cried a drowned voice. "watch ahead for the submarine!"

the submarine! sure enough, there was the submarine, silent stiletto, waiting beneath the sea to stab this fiery monster. madden's heart leaped into his throat. was it possible so slight an antagonist could engulf the battle cruiser?

the american turned and stared ahead over the shell-beaten sea with all his eyes. the little vulcan was now racing along some half-mile in front of the english battle line, her warning signal still stretched between her splintered masts. she rushed at top speed, vibrating under the stress of her engines. five or six miles ahead the german squadron had turned and was flying southward before the superior english force. flashes of fire and dull thunder still belched from their after turrets.

leonard tried to confine his attention to the adjacent waters in careful search for the diving boat's periscope, but the terrific spectacle across the smoky spangled sea gripped his eyes beyond his control.

the ship on the eastern wing of the teuton line was in flames. the fire burst out of the gun deck ports, lapping up over the boat decks in long red curling tongues. her cannon fire had ceased, and from what leonard could see, he thought the english ships had quit firing at her. she still fled southward, however. smoke began to roll out of her turrets, and her crew came swarming out on her deck like a disturbed ant's nest. through his glasses, madden saw them hunched against the fire, working to launch a boat, when of a sudden there was a blinding flare; a huge cloud of smoke leaped from the sea, and after four or five minutes, a thunder heavily audible even amid the roar of battle rumbled in madden's ears. it was the solemn note of a battleship destroyed by its own magazines. when the smoke cleared away there was left nothing save tossing waves and bits of flotsam here and there.

the horror of the tragedy was lost for leonard in another, more appalling scene. the right central battleship had lost control of her steering gear, and now she ran wildly amuck in the fleeing line like a drunken giant of steel.

through accident, or by the last shift of seamanship, she veered about broadside on, her huge guns still belching defiance. in crazy flight, she barely missed one of her own squadron, then rounded back in a great circle for the english line. no doubt her crew did not try to stop her, hoping that her unguided charge might work some damage to the enemy.

on she came, against the focussed storm of english cannon, her prow, forward turrets, bridge, masts, fairly disintegrated under a bastinado of twelve and fourteen-inch shells. yet it seemed as if she would survive it all and ram some english cruiser, when a cloud of steam broke out of her hold. a lucky shot had exploded her boilers. her wild charge ceased instantly, but her sub-calibre guns still chattered defiance at the crushing odds. giant shells were now pounding her at point-blank range. at some stroke of a cruiser to the right of the panther, the german ship heeled heavily on her starboard side.

through his glasses, madden could see the sailors still struggling to work the guns, though scores of them were wiped from the deck at every english shell. amid clouds of smoke the black cross of the german battle flag fluttered undaunted.

in a few minutes the enemy listed until her guns were at such a high angle they could no longer be trained against the enemy. her forward turret was completely blown away. bursting shells kept a constant glare around her. her boiler and furnace rendered her hold untenable, for her crew came out of the smoke and formed orderly platoons on her crippled deck. shells swept gaps through their files, but they closed again in regular formation, standing oddly erect on the tip-tilted deck. there was not a gun they could man, not a blow could they strike, yet the men stood firm in the steel cyclone sweeping across their shattered deck. then madden turned his lens on a group a little to one side of the main formation, and his eye caught the gleam of silver horns, the rise and fall of a drummer's arm, the fierce beating of a director with a baton. it was the ship's musicians. the band was playing, the men were chanting the battle hymn of the empire; out of the heart of the foundering cruiser, out of the souls of the passing warriors rose triumphantly, "die wacht am rhein."

sudden tears filled the eyes of the american and dimmed the splendid sight. he turned impulsively to his friend.

"caradoc! my god!" he screamed in his ear, "why don't they quit firing!"

"their flag is still flying—no doubt the halyards are shot away!"

even while smith screamed, a sudden and startling attack was launched from the panther's rapid fire and machine guns. they sounded a shrill treble amid the profound shaking bass of the giant cannon. the boys looked sharply about to see the object of this abrupt attack, when they suddenly heard the shrill whistling of steel all about their ears.

with the utmost horror, madden saw every tiny port spouting continuous flame in his direction. steel frothed the sea all around the vulcan. missiles struck the little tug and glanced off with sharp musical twangs. the crew of the little boat, who swarmed on deck, wonderstruck at the battle of the giants, suddenly darted to cover with wild yells.

"they're crazy! they're daft!" screamed madden. "shooting at us! what's the matter with 'em?"

caradoc, also, seemed to share the madness. he suddenly spun his wheel to the left, veered in a sharp circle, and dashed straight toward the course of the panther into the thickest of the hail. leonard stood beside him, frozen stiff, when straight ahead, he suddenly saw a periscope show for an instant, then disappear in a little swirl of water. the submarine had come into the action.

the tug rushed straight through the bullet-rumpled water to the point where the metal fin had disappeared, like a terrier dashing at a rathole.

with the disappearance of the submarine's "eye," the fusillade ceased abruptly. the great cannon were firing more slowly now and there came short intervals of comparative silence in the battle.

from the bridge caradoc bellowed fiercely at his men: "spread around the rail—keep a sharp lookout for the submarine!" the crew came back with a will now that they learned the bombardment had not been intended for them.

in the meantime the tiny david had put the great goliath to flight. the panther was endeavoring to save herself. she veered out of the thundering battle line and zigzagged easterly, in full flight from any enemy that she could almost drop down one of her smokestacks.

and the little vulcan swung about in an effort to keep up with her principal. on she rushed, shaking and puffing like a locomotive, her bright flags flying the submarine warning, as if the speeding giant ahead of her were likely to forget it.

suddenly hogan bawled out: "by th' port! by th' port, sir! there she rises!"

another shrill storm from the giant showed that the gunners aboard the panther also saw the periscope.

again the vulcan dashed at the diving terror as it disappeared and the cruiser swung clear around in a northerly tack. her commander was trying to outguess the man under the sea.

a strange game of blind-man's-buff the three dissimilar crafts were playing. caradoc assumed the submarine pilot would guess that the panther had fled north, and he sent the tug spitting along a course that would lie between the cruiser and her enemy. the panther was forced to repass the vulcan in the new maneuver. the giant and pygmy were flying along at top speed, fairly abreast, scarcely five hundred yards apart.

leonard took his eyes off the starboard sea a moment to look at the lion which this mouse was trying to nibble free, when suddenly, not thirty yards on the inside of the tug popped up the periscope.

the american rushed to the wheel, jerked it to the starboard. "yonder! yonder!" he bellowed in caradoc's ear, pointing.

again the guns shrilled forth; a steel sleet wailed about the vulcan. into the teeth of this blast, the tug circled and lunged.

with fascinated eyes, madden watched the periscope cut a swirling circle on the midst of the beaten water and straighten on the panther.

now the metal eye was directly under their swaying starboard. a moment they sped side by side, toward the imperiled cruiser. madden could almost have touched the wireless masts. a whine of bullets ripped one of their lifeboats like a saw and sputtered through the superstructure.

the periscope, which thrust six or seven feet out of water, disappeared under the swell of the vulcan's hull. suddenly the tug swung her blunt beak around with the sidelong blow of an angry swine. madden went flying to the right rail of the bridge to stare down at the imminent tragedy.

a dim shadowy bulk was hurtling through the blue water. suddenly, just as the tug's prow swung athwart her course, the submarine lined up straight with the panther. a great belching of bubbles wallowed up through the turbulent sea as a sign that the torpedo was launched.

a heart-stopping moment, in which the diving boat, the darting shadow of the torpedo, the blocking prow of the vulcan was clear.

a titanic upheaval of water; volcanic fires leaping out of the heart of the deep; a roar so absolutely appalling that it reduced the battle to a whisper!

the prow of the vulcan reared up and bent back over the main deck. in the same instant, out of the cauldron sea, an enormous cigar-shaped object was flung end-over-end, as a child flings a spindle. there was one flashing glimpse of conning tower, smashed plates. then a clap of surging air that seemed as solid as oak picked madden up as if he had been thistledown. he felt himself whirling through space. somehow, he caught a glimpse of a string of signals that had been blown from the wrecked masts of the shattered vulcan. then he felt a stinging blow of water as he hit the sea.

the submarine had destroyed both herself and the tug with her first torpedo.