“What do you take me for?” Harry asked almost fiercely.  “A baby?  Or a cold-foot?”

“Nothing like it,” answered Tom Reade with reassuring positiveness.  “You’re out of sorts, to-night.  Your head, or your nerves, or some thing, has gone back on you, and you walk through this blackness with half a notion that you’re going to walk over a precipice, or drop head-first into some danger.  With such a feeling it would be cruelty to let you go forward, chum, and I’m not going to do it.  I’ll go alone.”

The crouching figure to the rear of the young engineers quivered as though this separation of the two engineers on this black night was a thing devoutly to be desired.

“You’re not going to do anything of the sort,” retorted Harry Hazelton.  “I’m going forward with you.  I’m going to stick to you.  All I wanted was a minute in which to brace myself.  I’ve had that minute.  Now get forward with you.  I’m on your heels!”

Tom Reade shrugged his shoulders slightly.  However, he did not object or argue, for he realized that his chum was sensitive over any circumstance that seemed to point to sudden failure of his courage.

“Come along, then,” urged Tom.  “Wait just a second, though.  I’ll flash the light ahead along the wall, to show you that it’s all there, and just where it lies.”

A narrow beam of light shot ahead as Tom pressed the spring of his pocket flash lamp.

A weird enough scene the night betrayed.  In perspective the wall ahead narrowed, until the two sides seemed to come to a point.  Back of all was the thick curtain of black that had settled down over the gulf.  A little farther out, too, the water seemed rougher.  There would seem to be hardly a doubt that a gale was brewing.

“Shut that light off!” Hazelton commanded, fighting to repress a shudder.  “I can do better in the darkness.  Now, go ahead, and I’ll follow.”

Tom started, but he went slowly now, feeling that this pace was more suited to the condition of his chum’s nerves.  Harry followed resolutely, though none but himself knew how much effort it took for him to keep on in the face of such a nameless yet terrible dread as now assailed him.

To the rear a bulky, hulking figure rose and stood erect.  With the softest of steps this apparition of the night followed after them, until it stole along, ghost-like, just behind Hazelton.  Then a huge arm was raised, threateningly, over Harry’s head.

At that particular moment, as though insensibly warned, Hazelton stopped, half-wheeling.  In the next second Harry bounded back just out of reach of the descending arm, the hand of which held something.  But in that backward spring Harry, in order to save himself from pitching into the water, was oblige to turn toward Reade.

“Tom!” exploded the young engineer.  “Flash the light here quickly!”

In the instant, however, that Harry had sprung backward the figure had slipped noiselessly into the water to the left.  As Reade wheeled about, throwing on the light, he let the ray fall in the water to the right of the wall.  But no sign of the intruder appeared; the water had closed noiselessly over the now vanished figure.