430 SCIENCE OF HOME AND COMMUNITY 



Amount of air needed. There is some difference of opinion 

 as to just how much fresh air a child needs each minute. 

 There is a requirement in some states that enough air should 

 be brought into the room so as to provide each pupil with 

 thirty cubic feet of air per minute. These figures were 

 based on some theories which have been partly abandoned, 

 and some authorities to-day say that pupils do not need this 

 amount of fresh air. However, until we have more definite 

 knowledge regarding this matter, we can well afford to be 

 on the safe side of furnishing too much rather than too little 

 fresh air. The nearer we can approach the outside con- 

 ditions of abundant fresh air the better off we shall be. 

 The air must be changed often enough to remove the un- 

 pleasant odor arising from small particles given off from 

 clothing and bodies. 



Temperature. The best temperature varies in accord- 

 ance with a number of factors, such as the clothing worn 

 by the children and the kind of school work being done, 

 whether active or passive. It also depends on the humidity. 

 In the dry atmosphere found in most school buildings the 

 proper temperature is about sixty-eight degrees. If moisture 

 is added to bring up the proper per cent of humidity, a tem- 

 perature of sixty-five is sufficient. The temperature may 

 be kept even by means of a thermostat. If the temperature 

 runs too high, the thermostat shuts out the warm air and 

 opens the cold air damper wider, and if the temperature is 

 too low, the thermostat causes a reversal of this action. 

 Sometimes the thermostat shuts and opens the valves con- 

 trolling the steam entering the radiators. 



Humidity in schoolrooms. During the colder portions of 

 the year the humidity of our schoolrooms is too low. One 

 great defect in our ventilating systems is that they do not 

 have arrangements to increase the humidity. The average 

 humidity of schoolrooms in winter ranges from twenty to 

 thirty per cent. This is a very dry air and is detrimental 



