"Warriner's Shelf" at last, a natural bench in the escarpment, not larger than ten feet by six, with a comparatively level floor, and partially sheltered by the overhanging rock wall. The bushes and foliage in general had been cut away in front, leaving an irregular opening about the height of a man and four or five feet in width. "I should never have picked it out in the world," said Warriner, "but for that glint of white." And as he spoke, he detached from a hazel twig a square of cambric, a man's handkerchief. I followed the direction of his glance, and read the initials in one corner--"J. T." "What do you make of it?" I asked, feeling more than a little puzzled. "A signal, of course. A sharp eye could pick it out from the terrace, particularly if a hand was waving it." "Anyhow it is proof that John Thaneford knows of this eyrie and is accustomed to visit it," I added. "Perfectly. Do you realize, by the way, that we are now on Thaneford property?" "How so?" "The dividing line runs a few yards away, and you will find a monument near the base of that white pine. I came up here once with old Richard Hildebrand, and he pointed it out to me. This side of Sugar Loaf belongs to 'Thane Court.'" "Then we are trespassers." "In the technical sense I suppose we are." "And John Thaneford doesn't welcome visitors," I remarked, recalling the incidents of our first meeting. "Well, we're only looking around; no harm done." Warriner reloaded his pipe leisurely. "What do you suppose is the meaning of that contraption?" he continued, indicating a singular framework of iron, painted green, that stood in the opening and pointed directly toward the house; we both examined it with keen attention. It consisted of a narrow trough of metal--probably the half section of a four-inch pipe--and was some three feet in length. It was supported by tripods at either end, firmly fixed in the ground. The whole arrangement was solidly put together, and seemed intended as a rest for some sort of instrument. Warriner seated himself on a flat stone, and sighted along the trough. Then he supplemented his observations with the binoculars. "It appears to line exactly with the pridella opening of the 'Korah' window," he said at length. "Adjust a high-powered rifle in the trough, and it ought to be possible to send a bullet directly into the library at the 'Hundred'; yes, and it would strike pretty close to anyone who happened to be occupying the swivel-chair at the big teakwood desk. Of course, without instruments, I can't speak definitely about the trajectory, but we must be a couple of hundred feet above the house which should compensate for the natural drop in the arc." "The fatal objection to that theory," I retorted, "is the non-existent bullet. There can't be the slightest ground for thinking that Francis Graeme came to his death through the agency of a gunshot wound."