AT HOME ON WASHINGTON SQUARE Intended for family life, the New York brownstone is neat, cozy and decorous. The young lady's bedroom has an adjoining bath, of course, and "improving" pic tures on the wall. In the parlor, a new set of carved rosewood furniture and a vase of pampas grass, with a marble statuette for a conversation piece. Many curtains at each window; many patterns in each room.