I listened for ten minutes more, and still no sound came from the direction in which I had heard the whistle, save the distant neigh of a horse and the occasional barking of dogs. Yet my nerves were upset. That whistle _must_ have been a signal of some kind, and, if so, what did it portend? At last, being unable to arrive at any conclusion, I determined to lie down and think it over; and so, taking off coat and waist-coat, and putting on a loose wrapper, I threw myself upon the bed. It must have been after midnight then, yet I could not sleep, and at the same time thinking was an effort. I found myself listening intently for every sound, and holding my breath every time the distant bark of a dog or the lowing of cattle was heard. An hour passed; nothing further happened; and I began to feel drowsy at last and to regard myself as the easiest man to scare in the whole county. Soon after, I must have fallen into a doze; an uneasy, fitful slumber it must have been, too; for the very next thing I knew I found myself sitting bolt upright; every nerve strained; and listening with beating heart to the same signal whistle; only this time, though low and cautious, it was nearer; and, unless I was vastly mistaken, came from a little clump of trees just beyond the eastern fence. Harrod's big Newfoundland, who always slept on the porch in front of the house, and seldom, if ever, barked or made any disturbance at night, came tearing around to our side, growling fiercely, and evidently excited and alarmed.