From his pockets the big fellow brought out a coil of stout cord.  Without much trouble he slipped a noose over one of Tom’s wrists.  Then began an active fight, the object of which, on the black man’s part, was to make the other wrist secure.

But here Tom developed an amount of agility and a skill in fighting that angered Sambo.

“Doggone yo’, ef yo’ won’t take it peaceable-like, den yo’ll get it do odder way.”

With that, Sambo delivered a blow that made young Reade see stars.  His head swam dizzily.  Now, the black man secured the other wrist, making a turn and a knot that would have done credit to an expert.

But about that time something else happened.  Whack!  A blow from a club landed across the negro’s head.

“Who doin’ dat?” demanded the negro, blinking and half turning.

“I did eet, you miser-r-r-râble black smoke, and I do eet again!” rang the voice of Nicolas, as that valiant Mexican circled around the negro.

“Yo’ blow away, yaller baby!” jeered Sambo, whose head had been not at all hurt by the blow.

“I show you eel I run away!” bridled up Nicolas.

Tom now began to recover enough to know that his faithful servant was on the scene.

“Scoot, Nicolas!” urged Tom, in a gasping Voice.  “Run for all you’re worth.  This fellow will eat you up.  Run and bring help.”

“Senor, I can wheep him with one hand!” vaunted the little Mexican.

“Run, I tell you, and get help.  Be like a flash, man!”

“As you say, Senor, but-”

Nicolas turned, speeding away.

His escape, however, would interfere, possibly, with the plans of Sambo. 
The big black leaped up, racing after Nicolas.

As the Mexican was a little fellow, and short of leg, it was not long before the pursuer caught up with him.

“Hol’ on, yo’ yaller rascal!” laughed Sambo, reaching out for the Mexican.  Nicolas wheeled about, dancing out of reach of the negro’s massive hands.

“Stand still, yo’ li’l’ Greaser!” laughed Sambo.

“Now you have insult me, and I show you what I do to you!” snarled Nicolas, his brown face aflame at the taunting word, “Greaser.”

“Come heah!” jeered Sambo, making a bound and reaching for the small man.

Nicolas dodged, but he did not run away.  Instead, he bobbed up inside of the negro’s reach.  The Mexican thrust out his slim, sinewy right-hand forefinger.  A vicious poke he gave with it, landing sharply on a spot just about an inch and a quarter below the base of the negro’s breast bone.

“Woof!” panted Sambo, half doubling, for Nicolas had touched a tender spot.

“You have insult me!  You call me mean name!” raged Nicolas.  “Stand steel, you big black smoke!”

Again Nicolas ducked and rushed in.  Once more he employed his forefinger tip in the same fashion, and with more power.

“O-o-o-o-o-h!  Wow!” gasped Sambo, this time doubling nearly to the ground.  “Get away, chile!  I doan’ wan’ no mo’ ob yo’!”

“You have insult,” insisted Nicolas angrily, “and I do much more yet to you.”

This time the negro appeared almost helpless.  Nicolas danced about, looking for an opening.  In desperation Sambo struck out with his powerful left.  It gave the Mexican the chance he wanted.  Darting in, he repeated his trick for the third time.

The bulky negro lay down, groaning.  He had too little breath left to be dangerous.

While this was going on Tom Reade had rolled over on his face.  From this position he succeeded in getting to his knees.  Then he rose and hastened toward the Mexican.

“Nicolas, you’re surely a little terror!” Reade admitted, admiringly.  “Now, untie my hands and we’ll take care of Sambo.”

“Wait-jus’ one leetle moment, Senor,” begged the Mexican.  He turned back to Sambo, that forefinger ready for another jab.

“Fo’ de lub ob goodness-” gasped Sambo.  But Nicolas was determined.  He made the jab, and Sambo all but lost the little breath that was in him.

“Now, Senor, we do it all in one second,” proclaimed the Mexican.  From his pocket he drew a knife, springing the blade open.  Snip! snip! and the young engineer was free of his lashings.

“There’s plenty of this cord left,” declared Tom.  “We’ll fix up our black friend.”

“Do not use that word, Senor,” implored Nicolas.  “He is no good!  He is scoundrel!  He call me Greaser, an’ I will keeck off his head for eet!”

“Wait until we get him tied,” Tom proposed.

Sambo, by this time, had gained strength enough to sit up.  He was wondering whether he could rise to his feet and sprint away from this dangerous little fury of a Mexican.

“Wait, you black cloud!” cried Nicolas.  “I will put you down again!”

“Yo’ get away from me-please do!” begged Sambo, recoiling in terror.

“Sambo,” laughed Tom, “Africa shouldn’t have stirred up Mexico as you did.  Now, lie down on your face, place your hands behind you, and I will persuade him to let you alone.”

Sambo hesitated.

“Let me at him, Senor!” begged Nicolas, maneuvering forward, his right hand ready.  “He is no good, I tell you!  But I feex him!”

With a yell Sambo Ebony flopped over on his face, placing his hands behind his back.

“Let him alone, Nicolas, as long as he minds,” ordered Reade, catching the excited Mexican by the collar.  “Only, if he shows signs of making trouble then sail into him fast.”

No sign of trouble, however, was there in Sambo.  He lay as meek as a lamb while Tom used a lot of the spare cord in taking sundry hitches around the negro’s wrists.

“I don’t believe he’ll get out of that,” said Reade grimly, “Now, we’ll fix his feet.”

This, too, was done, and Sambo lay helpless on the ground.

“You’ll make a fine-looking jailbird, my friend,” mocked Tom, looking down at the prisoner.  “Nor did any man ever better deserve the striped suit that the State of Alabama will present you.  Now, Nicolas, I’ll stay and watch this black treasure while you run and find help.”

“Senor, you go yourself,” begged the Mexican.  “The men will obey you more queeckly than they would me.”

“Oh, you find some of the men and tell ’em to come here to get the fellow who has been blowing up the wall, and they’ll come fast enough,” smiled Tom.

“But, Senor, suppose thees scoundrel free himself?”

“I won’t let him, Nicolas.”

“But eef he do?” persisted the Mexican.  “Then, as I have shown you, Senor, I can take fine care of heem!”

“There’s something in that, too,” laughed Tom.  “Nicolas, I don’t believe it will be risking you any if I leave you here.  Besides, I won’t have to be gone very long.”

“If this black scoundrel he get restless, Senor, I will amuse heem with my forefinger.”

Sambo groaned; Nicolas grinned.

“All right,” Tom Reade laughed.  “I’ll be back as soon as I can.”

Away he raced at a dog-trot, chuckling.  The contrast between bulky Sambo and little Nicolas and the big negro’s comic fear of the slim little fellow kept Reade laughing.

“But where on earth did Nicolas learn that trick?” Tom wondered.  “I shall have to get him to show it to me.  Plainly that trick is worth more than all the muscle that I spent so many years in piling on.”

Tom headed his course for the shore end of the wall.  Here he would find men in abundance.  Moreover, now that the big black was a prisoner the men would hardly be needed on the wall.

“I think I know just how Sambo worked it, too,” the engineer reflected, as he ran.  “He swam out into the Gulf, towing that little scow behind him.  Neither his black head nor the little scow would be seen far on the water on a dark night.  Sambo, when he got near enough, could take one of the metal tubes, swim in under water to some point where no watchman was near, and stick the tube fast into the wall.  Then another tube, and another-all under water where they would not show to a passing watchman.

“Then, when he had all in place, and while no patrolling watchman was too near, Sambo could begin to attach the wires.  That would take but a few minutes.  Whenever any one came too near Sambo had but to swim out a little way and tread water until he could return to his job.  When, at last, all was complete, Sambo would attach a wire from the bombs to a wire moored at a stated point under water, and then swim in, work his magneto, and touch the whole thing off from a safe hiding place on shore.  The explosion itself would shatter the last length of wire.  Oh, but it was all slick and easy!”

Not increasing his speed, but keeping steadily at the jog-trot, Tom was at last near enough to the wall to raise his voice and shout.

“Hullo!” came back the answer.

“This is Reade, the chief engineer,” Tom answered, through the night.  “We’ve caught the fellow that has been blowing up the wall.  A half a dozen of you men hurry over here with your lanterns.  Come on the run.”

The man who had answered summoned several of his comrades as quickly as he could.  As the men had to come in from the wall, however, it took a little time.  Then six men reported, almost breathless, to Reade.  Still behind them came Corbett on the run, summoned from the boat.

“What’s this I hear, Mr. Reade?” puffed the foreman.  “You’ve solved the mystery and caught the fellow who has been dynamiting the wall?”

“Got him and he’s tied up, waiting for his ride to jail,” Tom chuckled.

“How did it happen, sir?” asked Corbett, staring with his eyes very wide open.

“I caught the fellow-a huge giant of a negro, the same fellow who got Hazelton the other night,” replied Tom.  “But before the fight was over the black ‘got’ me, instead, and had me tied up.  Then Nicolas came along and put the negro out of the fight, and-”

“Nicolas?” demanded Foreman Corbett incredulously.

“Yes.  Nicolas proved himself to be the most fiery little bunch of fighting material that I have ever seen,” laughed Reade, as they walked rapidly along.

“How could that Mexican wallop a giant?”

“I’ll ask Nicolas to show you, to-morrow,” Tom laughed mischievously.  “But, Corbett, I believe that four bombs are even now attached to some part of the retaining wall, ready to be set off.

“Great Scott!”

“They won’t be set off, though,” continued Reade.  “I found the firing magneto, and had a chance to cut the wires.”

The foreman wanted to ask more questions, while the half dozen workmen trudged along close at their heels, eager to hear every word.  Tom, however, suggested that they save their breath in the interest of speed, until they had Mr. Sambo Ebony in safe custody.

“Here we come, Nicolas!” Tom called, as the party neared the spot where captor and captive had been left.

There was no response.

“Nicolas!” Tom called again, with a start.

Still no answer.

“I don’t like the look of that,” Reade uttered.  “Let’s get there on the sprint!”

Tom himself caught at one of the lanterns, leading the way.  Neither the negro nor the Mexican was where the young chief engineer had left them.

Feverishly, Tom began to search the ground, holding his lantern close.

“Hang the luck!” he quivered, pointing to fragments of cord on the sand.  “That negro simply burst his bonds-and now where is he?  Where is Nicolas, for that matter?  I thought the little fellow, with his trick, could easily take care of the big black.”

But, though they spread out and searched, there was no sign of either the negro or the little brown man.

“I can’t understand what has happened,” quivered Tom Reade, thinking more of the staunch little Mexican than of the loss of the prisoner.