ox THE CONDITIONS OF HEALTH IN SCHOOLS. 461 



From the same observations it has been shown that a high degree of 

 humidity of the air does not interfere with the comfort and mental energy 

 of the scholars in a room provided that the temperature is not above 

 65° F. Above that temperature it produces marked decrease of mental 

 energy. 



The temperature most conducive to comfort and mental vigour 

 in a schoolroom is between 58° and 62°, irrespective of the degree of 

 humidity. 



Furthur investigation is required in order to determine the maximum 

 temperature of the air which may be introduced into a room without pro- 

 ducing physiological disturbance. It would be probably safe to state 

 that in no case should the temperature of the warmed air so introduced 

 exceed by more than one degree the proposed normal temperature of the 

 room. 



If a room supplied with warmed air becomes too cold, owing to loss of 

 heat through walls and windows, it should be further warmed by some 

 form of radiant heat. 



The Distribution in equal Proportion to each Occupant. 



It is generally assumed that in a mechanically ventilated room the air 

 is thoroughly mixed, so that the fresh air supplied is distributed in equal 

 proportion to each occupant. Further observations are required in this 

 respect, and also upon the best methods for securing this equal distribution, 

 the best position, size, and shape of inlet shafts, the relative sizes and 

 positions of inlets and outlets. 



In many schoolrooms ventilated mechanically inlets and outlets are 

 so arranged that shortcircuiting of the air-supply is inevitable, and 

 occasionally stagnant spaces are to be found. 



In ' naturally ' ventilated rooms the fresh air supplied during cold 

 weather inevitably gravitates to the floor unless it be warmed before 

 admission, forming a cold floor-current which chills the feet and lower 

 extremities of the occupants without materially contributing to the venti- 

 lation. 



The heat evolved from the body of each individual undoubtedly 

 causes a local upward current of air, and induces a fresh supply of air 

 to each body. The force of this upward current and its value so far as 

 it supplies fresh air to the individual require further investigation. It 

 probably contributes considerably to the special supply for each occupant 

 of the room, 



Ventilation as a Measure for reducing Bisks of Infection. 



By far the most important measure for the prevention of infection 

 when a scholar has contracted infectious disease is the px'ompt detection 

 and exclusion or removal of the infected individual. 



Another important measure is the regular and eflFective cleansing of 

 the floor, walls, ceiling, furniture, &c., in the room by means of damp 

 cloths in such a way as to remove the dust and the bacteria contained 

 in it without allowing them to be merely displaced and scattered about 

 in the air of the room. Efficient ventilation, however, can to .some 

 extent be made to help in reducing the risks of infection by removing 

 the majority of microbes present in the air. 



In the investigations of Carnelly and Haldane in 1886-89 it was shown 



