The ventilation of the sleeping room is not always so simple, especially where privacy demands the bolting of the chamber door. The diminished vitality of the individual during sleep requires that there shall be no draft over his bed. If there be but a single window, place the bed so as to escape the draft. Lower the upper sash about two inches. If there be two sleepers in the room lower it three inches. Raise the lower sash an inch or two. This gives three air spaces, top, bottom, and in the middle where the two sashes overlap. A thin board placed on edge in the window ledge, and fitting inside the window strip, will throw the current of air upward, and when the wind is strong, will prevent a draft. A transom over the door stimulates a gentle current of air, and is of great advantage. In some families, where privacy permits, the door is left slightly ajar at night. This, with a slight opening of an outer window, will secure ample ventilation. =Air Currents.=--A current of two feet per second is scarcely perceptible; of three feet is quite noticeable; of five feet is a positive draft. In introducing fresh air into a room the current should nowhere exceed two feet per second at the point of entrance. =Individual Requirements of Air.=--Each adult person requires three thousand cubic feet of air per hour. This will demand an opening or place of entrance equal to twenty-four square inches, and an equal amount of space for the foul air to escape. An opening four by six inches will give much more air than one twelve by two inches by reason of the smaller friction upon the sides. Ventilation through a single pipe or aperture is more effective than that through several apertures of equal aggregate area. =Stairs.=--Many persons, especially women, who, as a rule, do more stair climbing than men, find it very exhausting. Some stairs are easier to mount than others. In the construction of stairways, architects and builders should reduce the labor to the minimum. The wants of a certain invalid necessitated a constant going up and down stairs. The successive nurses were wont to remark, “I never saw, before, such an easy flight of stairs.” The exact measurements of this stairway are: seven and one-eighth inches rise; eleven and one-half inches depth, or space from the front edge to the back part of each step. There is a landing near the middle. A landing gives the climber an opportunity to get a full breath, and greatly reduces the effort of mounting. POPULAR HAND-BOOKS [Illustration]