ORIGIN AND USES OF ASPHALT. 539 



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 com- 

 municating 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 as- 

 serted 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 hun- 

 dred to three hundred cubic feet of air to each pupil ; have one or 

 more ventilators in the ceiling, or the w^alls near the ceiling ; have 

 long, high windows arranged to slide upward from beneath, and down- 

 ward 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 com- 

 pletely 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, accord- 

 ing 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. 



^> 



oeigi:n' axd uses of asphalt. 



By LEON MALO, C. E. 



"rDITUMEN" appears in nature as an accidental mineralogical prod- 

 -L-' uct, under the most diverse and often most inexplicable condi- 

 tions. It is found sometimes in the native state, sometimes mixed 

 with clays, sometimes as the cement of conglomerates, sometimes im- 



