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.
Beyond every thing, watch that no causes producing foul air are allowed to exist for a moment.