ioo CONTEMPORARY SCIENCE 



forces its way out through the Eustachian tubes into the 

 throat. If the outside pressure is increased, it sometimes 

 happens, particularly when the subject has a cold and 

 the Eustachian tubes are inflamed, that air does not pass 

 readily into the middle ear. Accordingly the tympanic 

 membranes are forced inward by the pressure; and this 

 may cause acute pain. Workers in compressed air are 

 accustomed, while going "into the air," i.e., into pressure, 

 to hold their noses and blow at frequent intervals as a 

 means for expanding the ear drums. Aviators even dur- 

 ing very rapid descents are generally relieved by merely 

 swallowing. 



To sum up all that has been said thus far, the influence 

 of low barometric pressure is not mechanical but chemi- 

 cal. Life is often compared to a flame ; but there are 

 marked differences, depending upon the peculiar affinity 

 of the blood for oxygen. A man may breathe quite com- 

 fortably in an atmosphere in which a candle is extin- 

 guished. The candle will burn with only slightly dimin- 

 ished brightness at an altitude at which a man collapses. 

 The candle is affected by the proportions of oxygen and 

 nitrogen. The living organism depends solely upon the 

 absolute amount of oxygen its so-called partial pres- 

 sure. 



Unlike the flame, a man may become acclimatized to 

 a change of atmosphere in the course of a few days or 

 weeks. He is thus adjusted to the mean barometric pres- 

 sure under which he lives. Every healthy person is so 

 adjusted, New Yorkers to a mean barometric pressure 

 of 760 mm. no less than the inhabitants of Denver or 

 Cripple Creek to their altitudes. Even your tall build- 

 ings could probably be shown to exert a slight climatic 

 effect upon the tenants of the upper stories. The study 

 of the processes involved in such acclimatization affords 

 us one of the most promising means of analyzing some 

 of the fundamental problems of life. In fact, is not the 

 gaseous interchange of protoplasm, the carbon and oxygen 



