60 THE REASON WHY: 



A {rood nose is requisite, also, to smell out work for the other senses.&quot; 



SHAKSPERZ. 



150. Why may the ticking of a watch fo heard distinctly 

 when it is placed against the teeth ? 



Because sound is capable of being produced by the &quot;vibration of 

 solid bodies without the intervention of the atmosphere, and in this 

 instance the sound is conveyed from the teeth, through the bones of 

 the face and the head, to the auditory nerves. 



151. How is the sense of smell produced? 



When we put a flower or a sweet scent of any kind to our nos 

 and enjoy the smell of it, it is because the nerves lining our nostrils 

 are touched by very small particles which fly off from the flower or 

 scent. In the same way unpleasant smells are detected by 

 minute noxious particles floating in the air, coming in contact 

 &amp;gt;riih the nostrils. 



152. Why do persons &quot;sniff up the air&quot; when any agreeable 

 odours are floating in it ? 



Because when the nostrils are thus exerted, they act as a species 

 of syphon, and withdraw a larger amount of the odour from the 

 atmosphere than they otherwise would, so that the action of sniffing 

 increases the pleasurable sense thus imparted. 



153. Why does closing the mouth increase the sense of smell ? 



Because under that condition the respiratory current is drawn 

 exclusively through the nose. On the contrary, when we wish to 

 avoid a disagreeable odour, the end may be effected by keeping the 

 mouth open, through which respiration will chiefly take place, 

 and very little through the medium of the nose. 



154. Why are the organs of smelling and of tasting situated 

 to near to each other ? 



Because the vicinity of these two senses forms a double guard tn 



