248 AIR. 



A. 1st The agitation assists the 

 liquor in bringing its hottest particles to 

 the surface : 



2ndly The action of stirring agitates 

 the air, and brings it quicker to the broth 

 or tea : and 



3rdly As the hottest particles are 

 more rapidly brought into contact with 

 the air, therefore convection is more rapid. 



Q. W Jiy is HOT TEA, Sc. cooled more rapidly 

 by BLOWING it ? 



A. Because the heated air is blown 

 more rapidly away ; in consequence of 

 which, cold air more rapidly succeeds to 

 absorb heat from the surface of the tea 

 or broth. 



Q. If a shutter be closed in the day-time, the 

 stream of light (piercing through the crevice) seems 



in CONSTANT AGITATION. WHY is this ? 



A. The air (in the sun-beam piercing 

 through the shutter-crevice) is more 

 heated, than that in its neighbourhood; 

 the convective current, therefore, is 

 distinctly seen, where little motes and 

 particles of dust are thrown into agitation 

 by the violence of the current. 



