All these things require common sense and care. Yet perhaps in no one single thing is so little common sense shown, in all ranks, as in nursing.[4] [Sidenote: Cold air not ventilation, nor fresh air a method of chill.] The extraordinary confusion between cold and ventilation, even in the minds of well educated people, illustrates this. To make a room cold is by no means necessarily to ventilate it. Nor is it at all necessary, in order to ventilate a room, to chill it. Yet, if a nurse finds a room close, she will let out the fire, thereby making it closer, or she will open the door into a cold room, without a fire, or an open window in it, by way of improving the ventilation. The safest atmosphere of all for a patient is a good fire and an open window, excepting in extremes of temperature. (Yet no nurse can ever be made to understand this.) To ventilate a small room without draughts of course requires more care than to ventilate a large one. [Sidenote: Night air.] Another extraordinary fallacy is the dread of night air. What air can we breathe at night but night air? The choice is between pure night air from without and foul night air from within. Most people prefer the latter. An unaccountable choice. What will they say if it is proved to be true that fully one-half of all the disease we suffer from is occasioned by people sleeping with their windows shut? An open window most nights in the year can never hurt any one. This is not to say that light is not necessary for recovery. In great cities, night air is often the best and purest air to be had in the twenty-four hours. I could better understand in towns shutting the windows during the day than during the night, for the sake of the sick. The absence of smoke, the quiet, all tend to making night the best time for airing the patients. One of our highest medical authorities on Consumption and Climate has told me that the air in London is never so good as after ten o'clock at night. [Sidenote: Air from the outside. Open your windows, shut your doors.] Always air your room, then, from the outside air, if possible. Windows are made to open; doors are made to shut--a truth which seems extremely difficult of apprehension. I have seen a careful nurse airing her patient's room through the door, near to which were two gaslights, (each of which consumes as much air as eleven men,) a kitchen, a corridor, the composition of the atmosphere in which consisted of gas, paint, foul air, never changed, full of effluvia, including a current of sewer air from an ill-placed sink, ascending in a continual stream by a well-staircase, and discharging themselves constantly into the patient's room. The window of the said room, if opened, was all that was desirable to air it. Every room must be aired from without--every passage from without. But the fewer passages there are in a hospital the better. [Sidenote: Smoke.]