and the problem becomes:  How to admit pure air throughout the house, and yet avoid currents and draughts.  “Night-air” is even more dreaded than the confined air of rooms; yet, as the only air to be had at night must come under this head, it is safer to breathe that than to settle upon carbonic acid as lung-food for a third, at least, of the twenty-four hours.  As fires feed on oxygen, it follows that every lamp, every gas-jet, every furnace, are so many appetites satisfying themselves upon our store of food, and that, if they are burning about us, a double amount of oxygen must be furnished.

The only mode of ventilation that will work always and without fail is that of a warm-air flue, the upward heated air-current of which draws off the foul gases from the room:  this, supplemented by an opening on the opposite side of the room for the admission of pure air, will accomplish the desired end.  An open fire-place will secure this, provided the flue is kept warm by heat from the kitchen fire, or some other during seasons when the fire-place is not used.  But perhaps the simplest way is to have ample openings (from eight to twelve inches square) at the top and bottom of each room, opening into the chimney-flue:  then, even if a stove is used, the flue can be kept heated by the extension of the stove-pipe some distance up within the chimney, and the ascending current of hot air will draw the foul air from the room into the flue.  This, as before stated, must be completed by a fresh-air opening into the room on another side:  if no other can be had, the top of the window may be lowered a little.  The stove-pipe extension within the chimney would better be of cast-iron, as more durable than the sheet-iron.  When no fire is used in the sleeping-rooms, the chimney-flue must be heated by pipes from the kitchen or other fires; and, with the provision for fresh air never forgotten, this simple device will invariably secure pure and well-oxygenated air for breathing.  “Fussy and expensive,” may be the comment; but the expense is less than the average yearly doctor’s bill, and the fussiness nothing that your own hands must engage in.  Only let heads take it in, and see to it that no neglect is allowed.  In a southern climate doors and windows are of necessity open more constantly; but at night they are closed from the fear referred to, that night-air holds some subtle poison.  It is merely colder, and perhaps moister, than day-air; and an extra bed-covering neutralizes this danger.  Once accustomed to sleeping with open windows, you will find that taking cold is impossible.

If custom, or great delicacy of organization, makes unusual sensitiveness to cold, have a board the precise width of the window, and five or six inches high.  Then raise the lower sash, putting this under it; and an upward current of air will be created, which will in great part purify the room.