"No indeed," Dr. Miller answered. "We own part of it, and a family named Hilleboe owns part. But it's not used for anything and we've never objected to the public using it. The local Boy Scout troops have taken on the job of keeping it clean as a regular project, and most people are careful. It's no trouble for us."

Rick glanced at his watch. It was getting dark rapidly now, and the apparition was due in fifteen minutes. The bridge was just ahead. They were in plenty of time.

"Strange," he thought. "The ghost of Captain Seth Costin, late of the Union Army, probably the Army of the Potomac, will perform for all comers promptly at nine. 'We regret there can only be one performance each evening.' Or was that true? Had anyone stayed to see? Maybe the obliging phantom performed every hour on the hour during darkness."

He shook his head as though to clear it of cobwebs. This didn't check with any ghost story he had ever heard. No holding hands around a table, no incantations or strange phrases in forgotten languages, no incense, no nothing. It was b.u.m theater.

The group crossed the bridge and entered the trees, still following the dirt road. Rick saw that the road forked, one branch going to town, the other to the picnic area. The trees around them were huge oaks, and almost certainly most of them had been healthy and along in years when Seth Costin fought among them.

Rick enjoyed the feeling of history, of a definite past. He resolved to do a little reading on the area.

Barby and Jan, who had been walking boldly in the van, dropped back now and the group seemed to huddle more closely together. There were voices among the trees, and here and there the glow of a fire. Then the edge of the tree belt was reached and the group stopped.

There was a clearing beyond the tree belt, and in the clearing were rough-hewn tables and benches. Beyond the clearing a gra.s.sy hill rose gently to an upland meadow, except for a section that rose sharply for nearly a hundred feet.

The upthrusting section was barren of gra.s.s, and at its base, boards were nailed across what was obviously the opening into the mine.

"Interesting formation, isn't it?" Dr. Miller asked.

It definitely was, and Rick said so. Even to his relatively untrained eye, this was a place where a volcanic fissure had opened ages ago, allowing igneous rock to thrust sharply upward through the sedimentary layers of the older ground. Now the formation had weathered until it was like a barren hill built on top of a fertile one. On the steep slope of igneous rock no gra.s.s had managed to get hold, although a few hardy weeds clung to it.

Barby pointed to a shelf, actually a terrace in the rock structure, above and a few yards to the left of the mine entrance. "He appears there," she said.

"Let's get a good position," Rick urged. "It's almost nine."

The sky was still blue in color, but it was already dark on the ground.

Fires flared up brightly, but the picnickers were hushed, as though they knew what was coming. They probably had not seen the ghost, and it was likely few believed they would see anything, but the unknown casts a strong web, and they were feeling its effects.

The Spindrifters moved along through groups of picnickers until they were directly opposite the old mine shaft, and took up positions in the shelter of an oak tree.

"There's a pool of water on top of that shelf," Dr. Miller told the boys. "It's from a spring, actually an artesian well. There's a pipe outlet up there from which water flows constantly. It collects in the pool, which overflows into a natural drainage ditch."

The scientist pointed to where the tiny stream made its way down the hillside and disappeared among the trees. "Over the years it has cut a natural channel to the creek. So far as anyone can remember, it has always been here. The pipe was replaced a few years ago, apparently by driving a new one into the hillside. The original well probably was driven during the Civil War."

Rick examined the terrain. "Odd, water coming out of a hillside like that, especially when the hillside isn't part of a mountain."

"The water comes off the Blue Ridge, and it develops a pretty good head of pressure in its underground channels. Whoever drove the original well simply tapped that hydrostatic head, although why they didn't drive the well at this level is beyond me."

A sudden scream from nearby brought the conversation to an abrupt end.

Rick turned in time to see a spout of water vapor, or something that made a white cloud, rise from the place where Dr. Miller had said the pool was located.

Rick felt a chill run through him and the short hairs on the nape of his neck bristled in a reaction older than the race of man. "You've got to keep calm," he warned himself sternly. "Be objective. Don't miss a thing!"

Scotty let out a low whistle, and Rick suddenly felt Barby's fingers biting into his arm. For, through the white rising mist, there came an officer in Union blue, and from under the broad cavalry hatbrim, piercing eyes looked straight at them.

Rick swallowed hard. He was vaguely aware of the terrified scurry around him as most of the picnickers departed as fast as their legs would carry them.

The apparition extended hands, as though in welcome to a loved one. The youthful, handsome face smiled.

Rick shook his head to clear it. This couldn't be happening! The apparition was faintly blurred, as though by the writhing of the mists in which he appeared, but details were clear enough. Rick could see the smile vanish suddenly, and shock replace it. He could see the gauntleted hands suddenly clasped to the chest, see red spurt from between the gloved fingers.

Jan Miller let out a long-drawn, soft, shuddering sound from between clenched teeth. Barby's fingers clamped tighter on her brother's arm.

Rick fought to shake off the feeling of horror and dread. "There aren't any ghosts," he tried to tell himself. "This isn't a ghost. There are no ghosts."

Except that he was looking at one!

The apparition began to fade, holding out b.l.o.o.d.y hands. The phantom officer swayed a little, and the young face was distorted with agony. It grew dimmer and dimmer until only the white mist remained.

Rick was aware of Barby's soft sobs next to him, but his eyes remained riveted on the white mist.

A yell from Scotty snapped him out of his reverie.

"Let's go, boy!"

Without quite knowing how it happened, Rick found himself next to his pal, climbing frantically up the rocky slope to the shelf, hurrying to catch the Blue Ghost before even the mist vanished!

Not even bothering to draw themselves to an upright position, the boys flung themselves forward into the rapidly vanishing mist. Rick felt with horror a thin, icy tendril curl around his face, and he heard a gentle bubbling sound, like phantom laughter.

Scotty's flashlight probed with a bright yellow beam, and Rick saw, in the instant before the mist vanished and all movement ceased, that the surface of the pool boiled gently and then was quiet.

The flashlight beam disclosed solid rock, broken only by the pipe from which water trickled.

There was no ghost.

There was no place he could have gone.

[Ill.u.s.tration: _There was no place the Blue Ghost could have gone_]

There was no sign of human handiwork.

There was--nothing.

CHAPTER IV

The Old Mine

Rick, Scotty, and the two girls stood in silence and surveyed the scene before them. They stood on the brow of the hill, looking down at the picnic ground, at the trees under which they had stood and watched a hair-raising apparition the night before.

Even in daylight the place somehow seemed eerie to Rick. The sun was shining brightly and birds came and went without fear or interference on their normal business of gathering food. A slight breeze ruffled the foliage of the oak trees.

It was a fine, normal Virginia summer day, with no trace of the supernormal or weird about it. Yet, Rick felt somewhat less than relaxed, and he certainly felt puzzled.

Directly below them the pool created by the flow of spring water glistened in the sunlight. Between their feet and the pool was solid rock, with only a few weeds struggling for life in an occasional crack.