For be it known to the reader, we have had our pen couched at John Allen for nearly two years. In the year 1865, the Sabbath after President Lincoln was assassinated, we began an exploration and sub- soiling of New York city, as to its crime, poverty, want, woe, wretchedness, and degradation, which we have pursued ever since, as other engagements would permit. Of course, it was not long before we found out John Allen. We at once recognized his genius for wickedness, and made him an especial study. But, as we have said, he baffles us. We have told him so, and have frequently asked him to help us out of our dilemma, but he always comes short of the complete thing. We _think_ we know why this Wickedest Man persists in living in his Water street den--that we have, in fact, penetrated his secret; but as we are not absolutely certain as to the matter, we will not set our suspicion down in print, lest we should do him injustice. We have said that our Wickedest Man is a phenomenon. We meant this in its application to the deepest springs of his character; but it is also, and perhaps equally, applicable to the external manifestations of those deepest springs. Has the reader any notion of a Water street dance-house? Concretely stated, it is a breathing hole of hell--trap-door of the bottomless pit. You step from the street into a bar-room, wherein lousy loafers lurk, and which is, in some cases, on a level with the sidewalk, and in others far below it; and there you are in the general midst of things, if it happens to be a dance-house of the very lowest class. But usually there is a 'saloon' in the rear of the bar-room. Passing out of the bar-room by a door opening in a partition across its rear, you enter the dancing-saloon, which varies in size from a room fifteen feet square to a room twenty-five to fifty feet in extent. Along the wall of this room a bench extends, usually on three sides. In the farther end of the room is an orchestra, proportioned in numbers and skill to the prosperity of the establishment. The number of musicians is sometimes as high as six, but the average is not more than three. In one of the rear corners of the saloon there is a small bar, where the girls can drink with their victims without exposing their fascinations to the unthriftful gaze of a non-paying and censorious outside public. Sitting upon the benches, or grouped upon the floor, or whirling in the dance, are the girls, varying in number from four to twenty, but averaging about ten. These girls are not often comely to the fastidious eye. But to a sailor, just from a long cruise where nothing lovelier than his weather-beaten shipmates has for years been seen, they are not without attractions. So, too, do certain landsmen, of a degraded type, pay homage to their strenuous charms. But a decent man, in the full possession and equipoise of his faculties, can only regard them with sorrow unspeakable, and pity too deep for tears.