THE ATMOSPHERE III 



their molecular activities the gases composing the atmosphere 

 expand outward away from the surface until the earth's 

 attraction overcomes their expansive power. This prevents 

 complete loss of these air particles into the vast spaces 

 surrounding the earth. 



By reason of the readiness with which air is compressed, 

 the lowermost layers in which man lives are the most dense. 

 As a person ascends a mountain or goes up in a balloon, there 

 is less and less of air (and of oxygen) in any one breath even 

 when the lungs are filled to their utmost capacity. As the 

 air grows more and more rarefied, in order to provide the 

 needed supply of oxygen the breathing is quickened and 

 becomes labored. In time distress is experienced, and a person 

 may become unconscious. In balloon ascensions resort is 

 sometimes made to artificial respiration, pure oxygen gas com- 

 pressed into tanks being taken along and breathed as needed. 



The notions of the ancients concerning the natural agencies 

 against which man has to contend, and whose nature was but 

 dimly comprehended if at all, is illustrated in the myth of 

 Aeolus 1 and his bag of winds. Disregarding any moral that 

 may be implied, there is no suggestion in it of any con- 

 ception of whence winds come and whither they go. Litera- 

 ture is filled with references to the winds. Poetry and song 

 abound in allusions to them in terms more or less true to 

 nature. It would be a great pity if, in coming to know 

 better the causes of natural phenomena, this age of scientific 

 thought and achievement should lose any part of the rich 

 inheritance of poetic fancy, though at times it does take 

 strange liberties with scientific fact. References of this 

 character range from the loftiest heights of prophetic vision 2 

 to the simple rhymes of the nursery 3 . 



1 See story of homeward journey of Ulysses and his companions. 



2 See Psalms 147, 148. 



3 See "T.he Wind" by Robert Louis Stevenson. 



