No one replied, because no one had a possible answer.

"Find the motive and you find just about everything else," Scotty commented.

"True enough," Rick agreed. "But if we can't guess a motive, let's try another tack. When did the ghost first appear?"

Barby answered. "Right after the Civil War."

Rick was patient. "I know. I mean, when did the ghost start making his recent appearances?"

"About a month ago," Dr. Miller replied. "We first heard about it from our tenant farmer when we arrived here from Spindrift. He was full of the news, as you can imagine. The ghost first appeared at a Girl Scouts'

campfire. An annual event. The girls are supposed to camp overnight.

Needless to say, they didn't."

Rick had a quick mental impression of uniformed girls scattering like leaves in a hurricane. "The appearances have been regular since then?"

"Yes. So far as we know, the ghost always appears at nine."

Rick scratched his chin thoughtfully. "I wonder if he appears when there's no audience?"

Scotty chuckled. "That's like the question about does a falling tree make a noise if there's no one to hear it. How can you tell?"

"I just wondered if the ghost would appear for a small audience, like one or two people."

"Meaning us," Scotty said with resignation. "When do we try, tonight?"

"Could be. Are there any picnics or meetings scheduled for tonight, Dr.

Miller?"

"Not that I know of. The next big affair is two days from now. The Sons of the Old Dominion have their annual steak and crab feast. This is the Old Dominion State, you know. It's a major event in this area."

"Then we'll try tonight," Rick stated, with a glance at Scotty. His pal nodded.

Over a second hot dog, then a third, Rick continued his line of questioning. Not until he began to ask more about details of mine ownership did one interesting fact come to light. Dr. Miller had received an offer to buy his property at a price considerably above the going market rates just before the ghostly appearances started.

"The offer wasn't for all the property," Dr. Miller added. "Only for the portion along our eastern line. It includes the field where you landed, the picnic ground, and our part of the mine property. The house and orchard were not included."

"How valuable is the part asked for?" Rick queried.

"Not valuable at all, except that the field could be used for hay or alfalfa. That's why I was rather puzzled."

"Who wanted the land?" Scotty asked.

"I don't know. The offer came through Jethro Collins, a local real-estate man. He said he was acting as agent for out-of-town interests that preferred to remain unknown for political reasons. It sounded fishy to me, and I refused."

"Because it might be crooked?" Rick asked quickly.

"No. That didn't occur to me. I thought that industrial interests might want the property, and I'm not anxious to have a glue works or something set up as a neighbor. Besides, I don't care for Collins. I'd rather not do business with him."

"Could the old mine have any value?" Rick persisted.

"No. The lead remaining is of such poor grade that it wouldn't be of any use. I'm sure that the mine would have been abandoned even before the Civil War if the South hadn't needed the lead so badly. Of course we're only part owners, anyway. My grandfather owned it jointly with the Hilleboes, our next-door neighbors. They own the property beyond ours, and uphill from the mine. We've never worried over the ownership of the mine itself, because it's worthless for any purpose."

Rick thought it was curious that an offer should be made for worthless property just as the ghost put in an appearance. It required looking into. He wondered how to go about it, and decided perhaps a chat with the real-estate agent might be useful. Dr. Miller readily gave his permission to try.

To Rick's other question, Dr. Miller had no answer--that was the odd location of the pipe from which the spring water trickled. The scientist could make only one suggestion. "Perhaps the hole was drilled vertically, and a horizontal feed put on for convenience. Then, later, the area was covered over by tailings from the mine, leaving only the horizontal pipe. After all, the pipe is not directly over the mine shaft. It is well to one side, perhaps six or eight feet."

That was a reasonable suggestion, and Rick let it drop for the time being. In fact, the boys let the entire subject drop for the rest of the afternoon, although Rick kept worrying the problem as was his way when confronted with a puzzle.

The Millers had a badminton court in the shade of an enormous old oak, and after a short pause to let the hot dogs digest at least partially, Rick and Scotty let themselves in for a series of trouncings by the girls, who had obviously been playing intensively. It was embarra.s.sing, to say the least, but neither boy begrudged the girls their success.

Not until dinner was ended did the subject of the ghost in Union blue come up again, then Rick started his probing once more.

"The business about an offer for the property may not be connected, but it's a curious coincidence. Now, what else happened about the time the haunting began? Any other facts, even unconnected ones?"

The Millers could think of none, but Mrs. Miller suggested that Belsely, their tenant, would know of anything new or unusual. Rick agreed to talk with him.

At eight o'clock, armed with flashlights, the boys departed for the old mine. They approached the area with caution, on the alert for any possible visitors. But the picnic ground was completely abandoned.

A quick inspection of the mine showed only their own footprints. The boards had been left off the entrance during their earlier inspection, and apparently no one had been there since. Then, at Scotty's suggestion, they looked for a place of concealment from which to hold vigil.

Rick found it, high in an oak. It was an easy climb, and from the huge limb they could look through a screen of foliage and see without being seen. Both boys were satisfied that they were un.o.bserved. No humans knew they were in the vicinity.

The Virginia mosquitoes were not so easily deceived. Both boys were promptly located by a scouting party, and mosquito communications went into fast operation. Within a few minutes the entire local mosquito air force had invaded the tree. Rick waved his hands futilely at the whining swarm and muttered unhappily, "There are so many they have to line up for a bite."

"I know," Scotty replied in a whisper. "I wonder if they bite ghosts?"

"We'll soon see. It's a few minutes to nine."

In spite of the insects, the boys concentrated on the catch basin, alert for any sign of the ghost. Their flashlights were ready to probe the apparition if it should appear.

Rick glanced occasionally at the luminous dial of his watch. Then, on the stroke of nine, he whispered, "Now."

Nothing happened. The boys bore the mosquitoes stoically and waited. Not until his watch showed 9:15 did Rick speak aloud. "Let's get out of here. I doubt that the ghost will be any later than this. He's not performing tonight."

They dropped to the ground and scratched luxuriously. Scotty shook his head. "No audience, no ghost. Mighty interesting."

"I'm with you," Rick agreed. "Now, suppose the ghost had known we were going to be there. Would he perform for an audience of two?"

"Good question."

"We'll try for an answer tomorrow night," Rick stated. "Tomorrow we'll spread the word around town that we're going to be watching, and let's see what happens."

Scotty scooped up a pebble and tossed it into the creek as they crossed the bridge. "You're sold on the man-made idea, huh?"

"Aren't you?"

"I would be if I had the slightest clue about how a ghost can be produced. But this one baffles me. No darkened rooms, no ghost trumpets, no knocks on tables, not even a chain clanking. A puff of mist and the ghost appears. How is it done?"

Rick didn't know. He didn't even have an idea. "The pool bubbled," he remembered. "That's our only clue. Why did the pool bubble?"