THE EAES 265 



pass from the place in a stream where a stone has 

 been thrown. It is estimated that sound moves 

 through air at the freezing-point at the rate of one 

 thousand ninety feet a second. When a wave of air 

 reaches the head, part of it is taken up by the auricle, 

 and directed into the auditory canal, where it sets the 

 drumhead in motion. The drumhead imparts this 

 motion to the chain of little bones that connects it 

 with the middle ear. The movement of the bones sets 

 the liquid of the inner ear in motion, and nerves 

 attached to the floating soft parts of the inner ear 

 carry the impressions thus received to the brain. 



So we see that the following are three of the things 

 that are essential to good hearing. The auditory 

 canal must be kept open and unobstructed. The 

 drumhead must be in proper position and condition 

 to respond to vibration. The chain of bones must be 

 free to move forward and backward in response to the 

 vibrations of the drumhead. Let us now give atten- 

 tion to a few common causes of disorder of these im- 

 portant parts, and find out how we may try to prevent 

 them. 



The auditory canal may be obstructed by impacted 

 earwax, by some object or substance that has ac- 

 cidentally got in, or by something that has been placed 

 in for a certain purpose and forgotten. The earwax 

 obstruction, as has been stated, has usually been packed 

 down by trying to swab or dig out an undue amount. 

 Trying to get out only what may be removed by wash- 



