THE NERVOUS SYSTEM OF MAN 1 59 



in man to respond to the vibrations taking place 

 in the air until they vibrate at least 30 times per 

 second. That vibrations exist in the air below 30 

 times per second can be proved mechanically 

 although man cannot hear them. The vibrations 

 which are interpreted as sound range from 30 to 

 30,000 per second and constitute the usual range 

 of the human ear. 



The vibrations in the ether are numerous and 

 mostly detected by various mechanical devices. 

 The electric waves range from zero to 30,000 bil- 

 lion vibrations per second; while 3000 billion to 

 800,000 billion vibrations per second produce 

 radiant heat which is detected by the skin. Light 

 and color are recognized by the eye when the vi- 

 brations are from 400,000 billion to 800,000 bil- 

 lion per second. There are no sense organs to 

 recognize the ultra-violet rays which vibrate from 

 800,000 to 5,100,000 billion times per second; 

 while X-rays are due to ether vibrations ranging 

 between 400,000,000 billion and 6,000,000,000 

 billion times per second. (Note: These facts on 

 vibration are taken from. Herrick's Neurology, 

 page 72.) One wonders what additional in- 

 formation would come to the brain of man if there 

 were sense organs that could respond to these 

 various physical vibrations. The evidence is con- 

 clusive that man can be aware of but a small part 

 of the activity In the physical universe, especially 



