288 ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 



probably is, partly due directly to the dry air which does not permit 

 the growth of the bacillus on solid substances or soil, but must also be 

 attributed to the migratory habits of the people, the outdoor life, and 

 the absence of centers of infection. Arabs, who were exempt from 

 phthisis and scrofula in their camps, died at the rate of 50 per cent 

 when they were located in French prisons. This is ouly one of many 

 instances which go to prove that the infective matter of consumption 

 clings to solid surfaces and thence invades the human system through 

 confined air. 



HEALTH AT HIGH ALTITUDES. 



The effect of living at high altitudes has been variously stated, but on 

 the whole it seems probable that most persons become acclimatized to 

 the rarity of the air, diminished pressure, lower temperature, lessened 

 humidity, and increased sun power. Above G,000 feet the pulse and 

 respiration rates are slightly increased. Dr. Marcet gave as the chief 

 outcome of several years' experiments on the amount of carbon dioxide 

 and air expired at high altitudes the following statements: 1 The effect 

 of altitude and cold combined increases the amount of carbon dioxide 

 expired, but where the cold does not become appreciably greater^as on 

 the Peak of Teneriffe, the amount remains the same as at the sea level. 

 At altitudes above 10,000 feet the amount is lessened. Less air is 

 expired at high altitudes. It appears that the blood more readily 

 acquires oxygen at high altitudes than near the sea level. The body 

 can gradually accommodate itself to altitudes much above 10,009 feet. 

 Eecent laboratory experiments by Dr. Loewy showed that the diminu- 

 tion of air density and pressure to about 17.717 inches is well borne, 

 greater rarefaction being balanced by deeper inspiration. A similar 

 compensation occurs when carbon dioxide is added to the air. Animals 

 breathing air rarefied to half an atmosphere eject the same amount of 

 blood from the heart as under normal pressure. 



The expansion of the chest and increased action of the heart add to 

 strength and vigor, and the mountain races, with the exception of peo- 

 ple living in deep or flat valleys, are generally fine in build. In the 

 tropics, Quito is an example of a large population doing well at a height 

 of 10,000 feet. For some forms of consumption, consumptive tendencies, 

 and several other diseases, such as anaemia, altitude is beneficial; for 

 others, including nervous irritability and heart weakness, it is harmful. 

 The elements which are concerned in these effects have not been identi- 

 fied. For old people and those who can not take much exercise, mountain 

 heights are clearly not well adapted. 



SEA AIR AND HEALTH. 



Sea air is very beneficial to the great majority of people, and has a 

 wonderful restorative power in many ailments and illnesses. It is free 



Proc. Roy. Soc, 1878, 1879. 



