"Hi've got as 'igh as eighteen knots out of 'er, sir."

"Signal 'full speed ahead' and call down to the firemen for all the steam we can carry."

"Very well, sir."

Caradoc looked at the light for a minute or two longer and then remarked to Madden.

"They couldn't have repaired that submarine for several hours longer.

They must have had two."

CHAPTER XIX

CHASED BY A SUBMARINE

Wheezing, coughing, shaking in every plate, vomiting into the sky a trail of smoke that extended clear to the eastern horizon, the _Vulcan_ shouldered her way at top speed across the mazy lanes of the Sargasso. The tug had come a queer crooked path across that sea, and the lay of her smoke trail down the pearly glow of dawn still marked her tortuous course.

Not a breath of air stirred, but the speed of the vessel sent a breeze whipping over the poop of the steamer where a group of battered men stared fixedly over the long frothing path of the screw. Several of the group wore bandages, two, unable to stand, sat in steamer chairs, all had the pale faces of all-night watchers, but every eye in the crowd scanned with feverish intensity the spangled ocean over which they fled.

The wind snatched at the clothes and bandages of the intent men. Masses of seaweed swept like gray blurs down the sheer of the tug's wake. Just beneath them the propeller rushed with watery thunder.

"Yonder she rises!" cried one of the watchers, pointing at two wireless masts that rose like the fins of a racing shark above the green surface of the Sargasso.

"Yonder she rises!" repeated a voice amidship, and more faintly still came the repetition from the bridge, "Yonder she rises--hard a-port!"

A sudden shift of the rudder shook the _Vulcan_ from peak to keelson. Next moment the tug was speeding squarely across a seaweed field, and another crook was added to the smoke mark in the sky. The _Vulcan's_ blunt prow drove through the seaweed at a great rate, while the clammy mass swung back together not sixty yards behind the churning screw.

A strange race had developed between the tug and submarine. When both crafts were on the surface in open water, the submarine had a knot or two advantage of the _Vulcan_ and could have picked her up in four or five hours. But early in the night Caradoc had discovered that the powerful screw of the steamer, designed, as it was, to propel vast loads, could make the higher speed across the algae beds.

On the other hand, if the submarine dived to escape the drag of the weed, she again became the faster craft. But, in this instance, when the submarine dived, the _Vulcan_ would immediately take to the open lanes and do more than preserve her distance. These constant shifts and turns explained the ricocheting course that was marked in smoke across the whitening dawn.

The submarine stood well out of water and skimmed along in the pink gleam like a long, slender missile. Its flat deck, wireless masts and conning tower stood etched in black against the morning light. She was consuming a fairish stretch of open water at a high speed.

"She's game for a long chase," observed Hogan, gently shifting a wounded arm in its sling.

Leonard Madden replied without removing his eyes from the rushing boat, "She has to be. All of Germany's naval plans depend on her destroying us."

"It does--and, faith, may Oi ask why?"

"If we get to Antigua and report this to the British admiralty, how long would this Sargasso reshipping arrangement last?"

"Right you are there, Misther Madden," agreed Hogan at once. "We'd woipe 'em out, wouldn't we? We'll make it, too. If we stood off th' little didapper all night, you know we can all day."

Madden considered the fleet little vessel. "No, I rather think she will capture us."

"And how's that?"

"The Sargasso doesn't extend indefinitely. In fact we are nearing the southern limit. Have you taken a look forward?"

"No, I haven't," said Hogan, taking vague alarm at Madden's tone.

"What's wrong?"

"I don't see many more big seaweed fields ahead. If she gets us in open water----"

"Why bad luck to it! Bad luck to it, Oi say!" cried Hogan as the wind whistled about him; "running us out o' the bushes loike a swamp rabbit."

Just then the submarine veered off her straight course somewhat to extend her open water run for two or three miles up the edge of the field. A length view showed her to be a delicate looking craft. Her sharp prow cut the water with hardly a ripple, in sharp contrast to the _Vulcan_, which shouldered up a waterfall as she lunged forward.

Suddenly, and rather unexpectedly, the submarine porpoised. There was a swash of foam, and she was gone.

The men on the poop stepped around to the side of the tug and stared anxiously southward. Bits of flotsam mottled the blue expanse, but it really appeared as if the saving drift weed were thinning to nothing.

Hogan glanced back over the way he had come.

"Sure it'll be a fair field and no favor, sweet Peggy O'Neal!" he hummed nonchalantly under his breath.

At that moment a violent shaking went over the _Vulcan_, and the short boat swung her prow about with tug-like promptness. It was as if the stout little craft had swung around on her heel.

"Faith and would ye shake a man's arrum off!" shouted Hogan at nobody in particular. "And are ye going back to meet the friendly little wasp?"

That was exactly what Caradoc was doing. He had swung the _Vulcan_ about in less than a hundred yard circle and was plowing straight back the way they had come.

The crowd on the poop held their breath at the daring maneuver. Tug and submarine were now rushing at each other full tilt, only one ran under water, the other on the surface. Suppose the submarine should thrust up a periscope for an instant--a cough of the torpedo tube and the _Vulcan_ would be blown to scrap iron.

The men on the poop ran forward, staring with frightened eyes over the gray-green soggy field through which the _Vulcan_ ripped her way.

It seemed fantastic to think that somewhere under that lifeless weed human beings spun swiftly along, freighted with the most terrific engine of destruction. What strange warfare! Who could have fancied that when savages began to use clubs to maul each other it would end in this diabolical refinement! Weapons, weapons, weapons--the history of man's undying savagery working under new forms of civilization! The war submarine--what a monstrous offspring of genius!

The sun rose like a white-hot ball in the brazen sky and the men held to the rails, mouths open, and stared ahead into the safe open water, expecting every moment for the _Vulcan_ to spatter skyward in a volcano of fire and steel.

The boat itself rattled along with that insensibility of mechanism that sometimes astounds an apprehensive man. Twenty minutes later, she turned into the open lane, and was rushing westward again at full steam.

An immense relief spread over the crew. Galton, who stood on the bridge at the wheel beside Caradoc, blew out a long breath and wiped the sweat from his face, Farnol Greer began a windy whistling of "Winona, Sweet Indian Maid." Madden felt as if a weight had been lifted off his brain.

Hogan was humming a tune. But all eyes turned anxiously seaward, to see where the submarine would "blow."

Ten minutes later, a distant ripple in the water caught their watchful eyes and the wireless masts popped up, on the opposite side of the great weed field, four or five miles distant.

A spontaneous cheering broke out on the _Vulcan's_ decks.

"Double crossed! Double crossed!" bellowed Hogan.

"Back track! We put one over! Hurrah for Cap'n Smith!" they shouted above the pounding of the engines.

Everyone but Caradoc wore the fixed exultant grin of the man who outwits his rival. The submarine had been thoroughly outgeneraled. North and west of the _Vulcan_ lay the whole Sargasso for an endless chase.

The diving boat had lost the great advantage of having the steamer cornered.