174 



ELEMENTS OF PHYSIOLOGY 



FIG. 148. 



board or a screen may be placed before the window to 



deflect the current upward and prevent its chilling those 



seated nearest the window (Fig. 148). If you find by 

 holding your hand near the inlet that there is 

 a good inward current, you may be sure there 

 is sufficient outlet; although if it is not far 

 enough from the stove, heat will be wasted. 

 If you know there is a strong outward cur- 

 rent, for instance, when a fire is burning in an 

 open fireplace, you may be sure that the 

 same amount of air is ' entering somewhere, 

 if only through minute cracks (Fig. 150). 



296. When over-enthusiastic people become 

 interested in ventilation, they sometimes in- 

 jure themselves by chilling draughts and low 

 temperatures. The temperature of the room 

 ^ou\d be kept between 65 and 70 degrees. 

 wooden strip at a. The foregoing directions for ventilation apply 



to cold weather. For warm weather no special directions 



are necessary, for most people are more unwilling to bear 



unpleasant heat or to soil their 



collars with perspiration, than 



to breathe foul air. 



297. The Five Degrees in 



Cleanliness. Nearly all peo- 



ple are very careful to wear 



clothes that are perfectly neat 



and clean. Dust or mud upon 



their clothes is considered the FIG. 149. Gallon's Fire Grate. 



highest degree of uncleanli- With a P as u sa s e be j ind . the grate that the 



air may be heated as it enters. 



ness. Many think it of the 



highest importance to health and refinement to keep the 

 skin clean by regular baths. But there are a few that 

 think it of still greater importance to keep the air clean 

 that goes into the lungs. A few also think it necessary to 



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