268 THE WONDERFUL HOUSE THAT JACK HAS 



the middle ear with sufficient force to assist the drum- 

 head in warding off the shock. The danger from loud 

 explosions is one that should be carefully guarded 

 against, for severe shocks to the nerves often cause 

 temporary or even permanent injuries to the ears. 



But one of the gravest and most common dangers is 

 the stoppage of the Eustachian tube, for such a stoppage 

 cuts off the middle ear's supply of air. Then, when 

 the air it contained before the stoppage is absorbed, 

 a vacuum is created, and the air outside the drumhead 

 naturally breaks through it to fill this vacuum. The 

 result is that hearing becomes permanently deranged 

 because of the puncturing of the drumhead and the 

 change in position of the chain of bones. 



The lining of the Eustachian tube is simply an ex- 

 tension of the lining of the throat and nose. Conse- 

 quently, colds, catarrh, adenoids, and kindred troubles 

 are common causes of the stopping up of the Eu- 

 stachian tube, because anything that affects the inside 

 of the throat naturally passes to the inner part of this 

 tube. Continuous mouth breathing, by irritating the 

 lining of the throat, may also cause the Eustachian 

 tube to become stopped up. If there is any derange- 

 ment of hearing after or during a cold, an aurist should 

 be at once consulted. Parents should watch their chil- 

 dren carefully for evidence of the ears being affected, 

 for deafness is so insidious that often it is not sus- 

 pected until accidentally found out by a physician. 



The same harmful result frequently attends certain 



