224 RADIATION. 



A. Because it is driven from grain to 

 grain by capillary repulsion. 



Q,. Why uill DEW-DEOPS ROLL over ROSES, 

 (&c. without wetting their petals ? 



A. The leaves of a rose contain an 

 essential oil, which prevents them from 

 absorbing the dew immediately. 



Q. Why can a SWAN or DUCK dive under 

 water WITHOUT being WETTED? 



A. Because their feathers are covered 

 with an oily secretion, which repels the 

 water. 



Q. What is the cause of MIST ? 



A. When currents of air from land 

 mix with currents of air from water, the 

 currents from the water are condensed 

 into mist by the colder currents blowing 

 from the land. 



Q. Why are the currents of air from the LAND 

 COLDER than those blowing over WATER ? 



A. Because the earth radiates heat 

 very freely, and (being greatly cooled 

 down) cools the air also which comes in 

 contact with it. 



Q. Why is not the AIR, which passes over 

 WATER, so COOL as that which passes over LAND? 



