180 



GENERAL SCIENCE 



FlG. 141. 



4. Remove one stopper at A on one side and at D on the other side. 

 Watch the candles. Tell which candle is getting a better supply of air. 



5. Open one hole at A and one at B, on the same side of the box. 



The candles will burn until used up, 

 which shows that the best ventilation 

 is obtained by having the openings at 

 the top and bottom on the same side of 

 the room. 



Disease and Fresh Air. Fresh 

 air cures many diseases, especi- 

 ally consumption. If fresh air 

 will cure disease, it will prevent 

 disease. 



When our ancestors lived in 

 the open air, disease and ill health 

 were not as common as now-a-days 

 with our crowded homes, over- 

 heated houses, and poorly ventilated school rooms. The open 

 air school is a step toward good health and prevention of disease. 

 Sleeping with our windows wide open, giving us plenty of fresh air, 

 helps to make us healthy. Live and sleep out of doors as much 

 as possible. Those who spend their lives in the open enjoy longevity 

 and the best of health. Even damp foggy air out-of-doors is far 

 more healthy than air in the house. 



Deep Breathing. " One hundred deep breaths a day" is an old 

 recipe for avoiding tuberculosis. Ventilate the lungs every day by 

 pressing the finger on the side of the nose so as to close one 

 nostril, breathing in through the other nostril, and then out of 

 the first. Reverse the process for every other breath. Singing 

 causes deep breathing, and is a good way of getting fresh air into 

 the lungs. 



Air Vitiated by Lights. Years ago candles were about the only 

 means of illumination. The replacing of candles by gas and elec- 

 tricity made lighting more convenient, as well as more hygienic. 

 In rooms where candles were used, the air was vitiated very rapidly. 

 Every candle vitiates as much air as twelve people. A Welsbach 

 gas light uses up as much oxygen as three people. This means that 

 a person in a room with one gas light must provide as much air as 



