The basement or cellar is ventilated by an opening into the exhausting air-shaft, to remove impure air, and a small opening over each glazed door to admit pure air. The doors open out into a “well,” or recess, excavated in the earth before the cellar, for the admission of light and air, neatly bricked up and whitewashed. The doors are to be made entirely of strong, thick glass sashes, and this will give light enough for laundry work—the tubs and ironing-table being placed closed to the glazed door. The floor must be plastered with water-lime, and the walls and ceiling be whitewashed, which will add reflected light to the room. There will thus be no need of other windows, and the house need not be raised above the ground. Several cottages have been built thus, so that the ground-floors and conservatories are nearly on the same level; and all agree that they are pleasanter than when raised higher. When a window in any room is sunk at the top, it should have a narrow shelf in front inclined to the opening, so as to keep out the rain. In small chambers for one person, an inch opening is sufficient, and in larger rooms for two persons a two-inch opening is needed. The openings into the exhausting-air flue should vary from eight inches to twelve inches square, or more, according to the number of persons who are to sleep in the room. The time when ventilation is most difficult is the medium weather in spring and fall, when the air, though damp, is similar in temperature outside and in. Then the warm-air flue is indispensable to proper ventilation. This is especially needed in a room used for school or church purposes. Every room should have its air regulated not only as to its warmth and purity, but also as to its supply of moisture; and for this purpose will be found very convenient the instrument called the hygrodeik,[2] which shows at once the temperature and the moisture. [2] It is manufactured by N. M. Lowe, Boston, and sold by him and J. Queen & Co., Philadelphia. The preceding remarks illustrate the advantages of the cottage plan in respect to healthful ventilation. The economy of the mode of warming next demands attention. In the first place, it should be noted that the chimney being at the centre of the house, no heat is lost by its radiation through outside walls into open air, as is the case with all fire-places and grates that have their backs and flues joined to an outside wall.