That night, as the sun went down on the one hand, the full moon rose up on the other, like the opposite side of an enormous scale. The river, too, was presently brimming with the flood tide. It was so still one could have carried a lighted candle from shore to shore. In a little skiff, we floated and paddled up under the shadow of Mount Vernon and into the mouth of a large creek that flanks it on the left. In the profound hush of things, every sound on either shore was distinctly heard. A large bed of ducks were feeding over on the Maryland side, a mile or more away, and the multitudinous sputtering and shuffling of their bills in the water sounded deceptively near. Silently we paddled in that direction. When about half a mile from them, all sound of feeding suddenly ceased; then, after a time, as we kept on, there was a great clamor of wings, and the whole bed appeared to take flight. We paused and listened, and presently heard them take to the water again, far below and beyond us. We loaded a boat with the decoys that night, and in the morning, on the first sign of day, towed a box out in position, and anchored it, and disposed the decoys about it. Two hundred painted wooden ducks, each anchored by a small weight that was attached by a cord to the breast, bowed and sidled and rode the water, and did everything but feed, in a bed many yards long. The shooting-box is a kind of coffin, in which the gunner is interred amid the decoys,--buried below the surface of the water, and invisible, except from a point above him. The box has broad canvas wings, that unfold and spread out upon the surface of the water, four or five feet each way. These steady it, and keep the ripples from running in when there is a breeze. Iron decoys sit upon these wings and upon the edge of the box, and sink it to the required level, so that, when everything is completed and the gunner is in position, from a distance or from the shore one sees only a large bed of ducks, with the line a little more pronounced in the centre, where the sportsman lies entombed, to be quickly resurrected when the game appears. He lies there stark and stiff upon his back, like a marble effigy upon a tomb, his gun by his side, with barely room to straighten himself in, and nothing to look at but the sky above him. His companions on shore keep a lookout, and, when ducks are seen on the wing, cry out, "Mark, coming up," or "Mark, coming down," or, "Mark, coming in," as the case may be. If they decoy, the gunner presently hears the whistle of their wings, or maybe he catches a glimpse of them over the rim of the box as they circle about. Just as they let down their feet to alight, he is expected to spring up and pour his broadside into them. A boat from shore comes and picks up the game, if there is any to pick up.