134 THE ENGINES OF THE HUMAN BODY 



separate houses or chambers were set up one by one in 

 which the various operations of life were conducted — until 

 such an arrangement of buildings came into being as is 

 now to be seen in a modern palatial farmhouse, where we 

 find the operations which went on in the one-roomed 

 hovel are going forward in a hundred separate buildings 

 or rooms. The cylinder of an internal-combustion engine 

 is a one-roomed hovel ; all the work of muscles, pumps, 

 and bellows is carried on in this one chamber, whereas in 

 the human machine we enter that palatial state where 

 separate establishments have been set up for the conduct 

 of each kind of operation. Such is the case in the human 

 body. If we want to understand the complexities of 

 modern civilization we find the clues when we trace them 

 back to their origin in one-roomed hovels. So too in 

 machines ; we find keys to unlock the complex ones when 

 we search for them in the primitive machines of simple 

 construction. That is the reason for our keeping a 

 steady eye on the motor cycle as we try to understand the 

 mysteries of the human body. 



Having made this explanation, we shall now proceed to 

 examine the respiratory chambers of the human machine. 

 We cannot miss them if we follow downwards the passage- 

 way taken by the breath. In fig. 33 a dissection has been 

 performed to expose the main throughway for the breath 

 in the nose, throat, and neck. When we take a breath, 

 the air, after passing the relatively narrow doorways 

 formed by the nostrils, finds itself in a warming-chamber 

 — the right and left cavities of the nose, between which a 

 partition has been set up. Internal-combustion engines 

 work better when they are supplied with warm air ; 

 hence they run better in summer than in winter. The 

 warming-chamber of the human machine has its side walls 

 thrown into scroll-like radiators, which are kept hot and 

 moist by the rich tide of blood which is being continually 

 pumped through them by the heart. The air is not only 

 warmed, but is also moistened and filtered in the chambers 

 of the nose. The colder the air breathed, the greater is 

 the tide of blood pumped through the radiators ; the 



