308 ADVANCED PHYSIOLOGY 



how much air a person needs. Taking everything into con- 

 sideration, those who have made a special study of ventila- 

 tion tell us that each person should be allowed from 2000 

 to 3000 cubic feet of fresh air per hour. This amount would 

 be contained in a room ten feet high, twenty feet long, and 

 ten feet wide. Fortunately, doors and windows are always 

 loose enough to allow a free passage of air through the cracks 

 around them, for if churches, schoolrooms, theatres, etc., wero 

 built with air-tight joints around windows and doors, they 

 would have to be made enormously large to meet the demands 

 of the crowds which gather in them. 



In arranging for the ventilation of rooms, it is well to learn 

 and remember a few general principles: 



1. A room may be well ventilated, but feel uncomfortable 

 because it is too hot. The temperature should never be 

 above 70 F, unless the room is occupied by very aged people. 

 Public halls and sleeping cars, for example, are often kept so 

 hot that they are very uncomfortable, even though there may 

 be good ventilation. On the other hand, the temperature 

 may be right, but the air may be poor. Too high a tempera- 

 ture with good ventilation is, however, the more common fault. 



2. For proper ventilation, a constant motion of air is needed, 

 not simply around the room, but from the room to the out- 

 side. If proper means for the escape of air is provided, 

 plenty of air will come in around doors and cracks, to take 

 the place of that going out. An open fire place is one of the 

 best methods of ventilation. A fire in a stove will serve the 

 same purpose, for it is constantly sending heated gases up the 

 chimney, thus drawing fresh air into the room. The belief 

 that stoves are unhealthful, because they use up the oxygen 

 of a room, is a great mistake. They use oxygen, but they are 

 constantly drawing in fresh air to replace it. On the other 

 hand, gas stoves or gas burners in a room will use up oxygen; 

 for generally they are not connected with any chimney or 

 proper outlet, and therefore fill the air with the odor of burned 



