The Commissioners on Improving the Sanitary Condition of Barracks and Hospitals, in their report (1861) recommended for _inlets_, one square inch for every 60 cubic feet in the contents of the room; or one square inch for every 120 cubic feet in the contents, if warm air is admitted round the fire-grate. For _outlet_ shafts on lower floors, one square inch to every 60 cubic feet, slightly increasing for the higher storeys. =Amount of Air-space required.=—We may take 3,000 cubic feet of air as the average amount of air required hourly by each individual, and inasmuch as the air of a room cannot be changed oftener than three times an hour without producing an unpleasant draught, it follows that at least 1,000 cubic feet of space must be allowed per person. This may be compared with the amount actually supplied under various circumstances. In the British Army for each soldier— In permanent barracks 600 cubic ft. In wooden huts 400 „ In hospital wards at home 1,200 „ In hospital wards in the tropics 1,500 „ In general hospitals 1,000-1,500 „ In fever hospitals 2,000-3,000 „ In workhouse hospitals 850-1,200 „ In common lodging houses 300 or 350 „ Do., if occupied night and day 350 or 400 „ In workhouses 300 „ In schools— London School Board requires per scholar 130 „ English Educational Code per scholar (minimum), in old schools 80 „ Do., in new schools 120 „ _Floor-space_ has an important bearing on ventilation. In calculating the available cubic space of a room, the height over 12 feet should be disregarded. Thus, if 500 cubic feet is allowed for each individual, the floor-space should be 42 square feet. In barracks, soldiers are allowed 50 square feet of floor-space. In the Government regulations for workhouses it is stated that there must not be more than two rows of beds, and that the height of rooms above 12 feet must not be reckoned. This gives a minimum floor-space of 25 square feet per occupant, or with dormitories 17 feet wide, a bed-space of about 3 feet.