They labored on until evening set in once more, and all hands had just been ordered aft to secure a broken spar, when Nick the boy uttered a fearful cry, which gave every man a start. They followed the direction of his horrified gaze, and saw a danger which paralyzed the stoutest nerve. Just ahead was a "gray-back,"--sailor parlance for a wave which is to all other waves as a mountain to a hillock, --and Reuben felt their doom was sealed, for the old Nautilus, disabled as she was already, could never stand that terrific onslaught.