HEHPIUATION AND THE VOICE. 129 



in a thin sheet, and so is warmed by the warm walls of 

 the cavities. It passes through the mouth in a large 

 stream, and pours into the lungs without being properly 

 warmed in cold weather. 



2. Dry air, passing through the nasal cavities, is not only 

 warmed, but moistened. When it is taken through the 

 mouth, it dries the throat, as any one can learn by trying 

 it rapidly for a few moments. Hence, the practice tends 

 to produce sore-throat. 



3. Snoring is a result of sleeping with the mouth open. 

 The soft palate, which hangs like a curtain between the 

 passages from the nose and the mouth, is relaxed in sleep. 

 The two currents of air, one on each side of it, cause it to 

 vibrate rapidly, just as a sheet will flap and rattle in the 

 wind. 



6, The habit of breathing through the nose, both in 

 waking and sleeping hours, should, therefore, be culti- 

 vated. One of the best safeguards against catching cold in 

 the throat, on going from a heated room into the night 

 air, is to keep the mouth shut. 



7, The throat is both a food-passage and an air-passage. 

 Air is sometimes swallowed into the stomach : food and 

 drink sometimes enter the wind-pipe ; but, if they do, there 

 is a great disturbance, and they must be coughed out at 

 once. Commonly, each takes its proper course, the food 

 through the gullet, the air through the wind-pipe, and that 

 without any thought on our part. The apparatus is self- 

 regulating. When we swallow, the breathing-passage 

 closes up tight; and a kind of trap-door, called the epi- 

 glottis, shuts down over it. You can not swallow and 

 breathe at the same time. 



8, The larynx, which is the upper part of the wind- 



