air and the lighter animal exhalations would be compelled to descend to the level of the top of the communicating door in order to escape. This they can not do, for it is in opposition to gravity. If no other outlet is provided, the only ventilation will be by diffusion through the doorway with the purer air in the hall. The animal exhalations will fill the room from the ceiling to the level of the top of the communicating door, and there remain. It would cost but a trifle to have one or two ventilators put in the ceiling of a school-room where there are none in the walls; and school directors could not make a better investment of the money. Children will not study, and can not be persuaded or compelled to study diligently, in the foul and stifling air of a crowded and wretchedly ventilated room. It may be safely asserted that in a majority of our schools the ventilation is insufficient, or not properly attended to, either on account of lack of knowledge or attention on the part of the teacher, or the defective construction of the building. A sanitary inspection should be made of every school in the State by a competent medical inspector; and all the schools found defective in this (or any other way injurious to health) should have all such defects remedied, or otherwise be condemned as unfit for school purposes, with the imposition of penalties for using them as such.
A school-room should have a high ceiling; contain from two hundred to three hundred cubic feet of air to each pupil; have one or more ventilators in the ceiling, or the walls near the ceiling; have long, high windows arranged to slide upward from beneath, and downward from above. All the children should be sent out at recess, if only for a short time, in order to have their clothing—saturated as it usually is by animal exhalations—exposed to the purifying influence of the open air, and doors and windows thrown open in order to completely change the air within. Stoves, chimneys, pipes, etc., should be carefully looked after, and any accident or defect promptly attended to, or immediately reported. Children convalescing from contagious diseases should be excluded from school for weeks, or months, according to the recognized limit of contagiousness of the disease. It should not be forgotten that the school and the church are the two great centers for the communication of contagious diseases; and that both are active in this way in direct proportion to the insufficiency of the ventilation.
| ORIGIN AND USES OF ASPHALT. |
By LEON MALO, C. E.
BITUMEN appears in nature as an accidental mineralogical product, under the most diverse and often most inexplicable conditions. It is found sometimes in the native state, sometimes mixed with clays, sometimes as the cement of conglomerates, sometimes im-
