CHAPTER XII. SCHOOL HYGIENE. A LARGE proportion of the ill health of a community is found in children of school age, and since such a high percentage of this ill health can be prevented, it is necessary to treat briefly the subject of school hygiene. Site, or Location, with Reference to Drainage Capacity of the Soil.-In school architecture a question of primary importance, the consideration of which is frequently neglected, is that of location with regard to the nature of the soil and its drainage capacity. Satisfactory sanitary arrangements can rarely be secured in any building unless the site of the building is carefully selected with regard to the drainage capacity of the soil. The soil structure as regards the preponderance of definite-sized grains, coarse or fine, influences the drainage capacity, and consequently the healthfulness of the site. The amount of slope and the proximity of streams, either surface or underground, also influence the character of the soil. For these reasons it is of primary importance that the site selected for a school-building shall be of such a nature as to afford the very best facilities for drainage, not only for refuse and excreta collected in the building, but for surface- and rain-water flowing over the soil. Whenever the soil of the site is not perfectly dry, it should first be underdrained. Parkes states that the conditions which insure healthy habitations are: I. A site that is dry and not malarious, and an aspect which gives light and cheerfulness. 2. A pure supply and proper removal of water, by 18 273 means of which perfect cleanliness of all parts of the house can be secured. 3. A system of immediate and perfect sewage removal, which renders it impossible that the air or water shall be contaminated from excreta. 4. A system of ventilation which carries off all respiratory impurities. 5. A condition of house construction which insures perfect dryness of the foundation, walls, and roof. Structure of Walls.-Having selected a proper site for the building, the nature of the building is of considerable importance. The building itself should be detached, so as to obtain an abundant supply of fresh air and the greatest amount of light. The character of the materials composing the walls and the thickness of the walls, the number of layers composing them, all have an important influence on the character of the building. The walls should be rendered impervious to moisture, and it is preferable, therefore, to have double walls with an air space between the inner and outer surface. The materials employed in constructing the walls will be governed by circumstances, and their nature is not of great importance if they are properly used. Stone walls are usually somewhat damp, but can be rendered perfectly dry by allowing an air space between the inner and outer layers. Cubic Space and Floor Space.—Cubic Space.-From calculations made by Prof. Parkes and Dr. de Chaumont, the amount of air required for each adult per hour, in order to maintain a certain degree of purity in the atmosphere, is 85 cubic meters. The respiratory impurity added to the air will, of course, be less with children than adults, consequently the amount of air required to maintain the standard of purity will be less. Though children evolve less carbon dioxid in a given time than adults, yet relatively for their body-weight they expire more. fixing a standard for schools, the age of the children ought also to be considered; the average amount of air re In Parkes says quired being about 55 cubic meters per hour. that it is highly desirable that some general agreement should be arrived at as to the amount of air necessary, even if it be admitted that the desired amount cannot always be obtained. If we adopt the following amounts of carbon dioxid as being evolved during an hour in repose, we shall not be far from the probable truth: Adult males. (say 70 kilograms weight), 0.72 cubic foot 20 liters. Average of a mixed assembly The amount of fresh air that must be supplied in order to prevent the impurity due to products of respiration exceeding a particular limit, is measured by the quantity of carbon dioxid present in excess over that in external air, according to either of the standards in use, and may be calculated from the formula d, where e = amount r of carbon dioxid expired in liters per head per hour; r = admissible limit of carbon dioxid due to respiratory impurity, stated per liter; d= delivery of fresh air per head in cubic meters. Under these conditions the amount of fresh air to be supplied in health during repose ought to be: The law of Massachusetts requires that each occupant of a school-room receive a quota of 850 liters of air per minute. If this is taken as the basis for the minimum amount of air required by each child, and we require further that the air be changed but three times each hour, then the minimum amount of cubic space allowable for each child is 17 cubic meters. This is slightly lower than the theoretical amount, as shown by the calculations of Parkes, but it is far in excess of the amount of space usually supplied in common schools. When the air of a room is changed more frequently than three times an hour, there is always more or less draft in some portions of the room, and for this reason the minimum amount of space allowed should be 17 cubic meters. Even with this amount of cubic space it is impossible to keep the air of rooms of the same purity as outside air, owing to the gases given off during respiration. For this reason a certain amount of respiratory impurity, as it is called, is permissible in wellventilated rooms. With the outside air containing 0.4 part in 1000 of carbon dioxid, the additional amount permissible as coming from respiration is 0.2 part in 1000, making a total amount of carbon dioxid in the air of 0.6 part in 1000. It should be our aim in the ventilation of school-rooms to maintain the respiratory impurity at this low standard, and this it is possible to do if the initial cubic space is sufficient-say 17 cubic meters-and we have reliable mechanical means for introducing the requisite amount of fresh air each hour. If the cubic space is less, or the arrangements for the introduction of fresh air are imperfect, it is impossible to have perfect ventilation and pure air. It is, therefore, merely a matter of choice on our part whether we will elect to have efficient ventilation or not. It can be obtained by making the necessary expenditure. Without this it is impossible to obtain it. Floor Space. Each child should have a floor space of at least 4.25 square meters. This amount of floor space, when the height of the room is 4 meters, will give each child a minimum cubic space of 17 cubic meters. The amount of floor space is an important factor, inasmuch as it is brought into relation with the height of the room. Relation of Window Space to Cubic Space.-In fixing the height of stories, when not governed by the amount to be expended, the height of the basement should be 2.8 to 3 meters. The first story should be The sills of 3.9 and the second story 3.8 meters in height. Light in rooms of the second story is always superior to that of the first, consequently the increased height of the first story. There is also usually an increase of glass surface provided for the first story to equalize the difference in light. The window heads should be finished to the top, so that no shadow can be thrown on the ceiling. windows should be 1 meter from the floor. tion of light to floor of class-rooms should never be less than I square meter of glass surface to 6 square meters of floor surface, for rooms 10 meters wide, lighted from only one side. Within the limits of a city, where the adjoining buildings are about 6 meters from the exterior walls, this proportion should be increased to 1 to 5. The length of the school-room should not be over 15 meters, and the width not over 10 meters, while the height should be at least 3.8 meters. Lighting.—The lighting of school-buildings is a matter of very great importance. The windows should never be in the front of the room, only at the sides and rear. It is preferable to have them on the left side of the room, so as to have the light falling over the left shoulder of the pupil. The windows should be provided with shades or blinds, so that direct sunlight can be excluded as required. As the sense of sight is the chief medium of education, it is hardly possible to overestimate the importance. and necessity for carefully observing the management of light in school-rooms. It has been positively established by careful and extensive statistics that myopia is most frequently, if not exclusively, developed during schoollife. This is due partly to the fact that the eye during this period of growth is more liable to change in form, and partly to the fact that children have much stronger power of accommodation than adults, and therefore hold objects more closely to the eye. The book or paper should never be closer to the eye than 25 centimeters. If there is myopia sufficient to prevent the letters from |