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 grass 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.