11. The apartments should provide a large cubic space for air; because plenty of air is essential to the health and comfort of the inmates. The apartments should therefore be as large and lofty as possible.
12. The apartments, besides providing a large cubic space for air, should also provide for the escape of the foul and admission of fresh air; because, however large an apartment is, the air is sure to become deteriorated and contaminated when the apartment is occupied by living beings. There should, therefore, be two special openings to each apartment, one for the escape of the foul air, and another for the admission of fresh air. There must be two openings, an outlet and an inlet. It is useless to make one without the other; it is useless to make an outlet unless there is also an inlet, for no air can go out if none comes in. This is a self-evident fact; still it is very frequently disregarded into ventilate apartments. There will, for instance, be a perforated or louvered pane in the window, a perforated brick or grating in the wall, an Arnott's ventilator in the chimneybreast, an opening above the gas, with a tube leading to a grating in the wall or into the chimney smoke-flue, or some other contrivance for the escape of the foul air, while there is no opening at all for the admission of fresh air; and the doors and windows are made to fit as tightly as possible, and even list put round them to prevent any possibility of air getting in by them, as though that could go out which never got in! In these cases, if the outlet act at all as an outlet, it must obtain its supply down the chimney—hence a smoking chimney; but generally, instead of acting as an outlet, it becomes an inlet to supply the current up the chimney, and always so when the fire is burning—hence the cold draught so generally complained of from the ordinary ventilators, and hence the reason that ordinary ventilators are so generally closed up in disappointment and disgust, and ventilation decried as a nuisance, failure, and farce.
13. These openings providing for the escape of foul air and the admission of fresh air should, both of them, be special and permanent, and altogether independent of every other arrangement of the house; such as opening the windows, doors, chimneys, etc.; because the escape of foul air and the admission of fresh air are most needed when, in consequence of the coldness of the external air, we close the doors and shut the windows. Special ventilation is most needed in winter, in cold, frosty weather, with an east wind blowing, and when we are very careful to shut the doors and windows, and adopt every other means we can to exclude the out-of-doors air, particularly of sitting at table for meals, or round the fire for evening entertainment.
14. The outlet should take the foul air from the upper part of the room; because the foul air, being more heated, is specifically lighter than the fresh air, and so rises to the upper part of the room. The outlet should, therefore, be in or near the ceiling.