Weather 123 



ture from the body too rapidly, producing irritation, especially in 

 the linings of the nose, throat and windpipe, which should always 

 be moist. If the air is too moist the necessary giving off of mois- 

 ture by the 'body is checked. We cannot regulate the outdoor 

 humidity, but we can frequently regulate the humidity of the 

 indoor air. 



Popular Science Monthly. 



USING THE HYGROMETER 



Note the difference in degrees shown on the wet and the dry bulb thermometers 

 and find the relative humidity of the room. (See table, page 124.) 



From the standpoint of health, the relative humidity, or the 

 ratio of the amount of moisture actually present to the amount 

 the air could hold if fully saturated, should be at least 50 per cent. 

 Relative humidity is determined by means of a hygrometer and 

 of a relative humidity table. 



