A STUDY OF RESPIRATION 227 



former should enter a room near the ceiling. As it cools it 

 gradually settles toward the floor, and the openings into the 

 ventilating shafts should be found at the lower part of the 

 room. If the system works properly, there will be a con- 

 tinuous supply of warm, fresh air, and at the same time the 

 air that has once been used will be drawn off through the 

 flues. 



Unfortunately, in most of our dwelling houses little pro- 

 vision has been made by the builders for proper ventilation. 

 Hence, if the rooms are heated by steam, we frequently 

 breathe over and over some of the air that has been already 

 expired. This can be obviated, however, by ventilating in 

 the following way. A piece of board two or three inches 

 wide should be fitted across the lower end of the window 

 opening. When the lower sash is pulled down upon it, a 

 space is left between the upper and lower sashes, through 

 which fresh air may enter the room without causing a direct 

 draught. In order to secure a proper circulation of air an 

 opening of some kind should be provided at the opposite 

 side of the room. 



Furnace heat is much more satisfactory than steam from 

 the point of view of ventilation, for in this way a continual 

 supply of fresh air is furnished. An open fireplace is one 

 of the best means of removing foul air, and when a fire is 

 burning a strong current up chimney is assured. 



Proper Methods of Sweeping and Dusting. It is impossible 

 to prevent all dirt particles and bacteria from entering the 

 respiratory organs, especially when one lives in a city, yet 

 the amount of irritation and the chances of acquiring disease 

 can by proper care be greatly lessened. The number of 

 germs of various kinds that may be found in a church, school- 

 room, theater, or living room has been proved by a long 

 series of experiments to be enormous, for with the ordinary 

 methods of cleaning these rooms, very few of the germs are 

 removed. When a room is swept, most of the light dust 

 particles and bacteria are raised from the floor and mingled 



