WEATHER. 147 



A. Because the air is suddenly and 

 very greatly rarefied ; and (as the density 

 of the air is diminished) its power to 

 transmit sound is diminished also. 



Q How do you KNOW that RAREFIED air 

 CANNOT TRANSMIT SOUND so well as dense air? 



A. Because the sound of a bell 

 (in the receiver of an air-pump) cannot 

 be heard at all, after the air has been 

 partially exhausted; and a pistol fired 

 on a high mountain would not sound 

 louder than a common cracker. 



Q. Why dD we FEEL BRACED and LIGHT- 

 HEARTED on a FINE spring or FROSTY morning ? 



A. 1 st Because there is more oxygen 

 in the air on a fine frosty morning, than 

 there is on a wet day : and 



2ndly A brisk and frosty air has a 

 tendency to bract the nervous system. 



Q. Why do DOGS and CATS (confined to a 

 room) feel LAZY and DROWSY at the approach of 

 rain ? 



A. 1st Because the air does not 

 contain its full proportion of oxygen: and 



2ndly Because the damp relaxes their 

 nervous system, and makes them drowsy. 



o 2 



