ICE MELTING FROM A TWIG 



Ice forms on trees fiuriiiK a rain, i)articularly when the lemjjerature of a thin layer of air on 

 the ground is helovv freezinf(, hut the temperature of the air above is warmer, thus prevent- 

 ing the rain from turning to sleet. In this jjhotograph (highly enlarged) the iee has begun 

 to melt, and in doing so clearly reveals its crystalline structure, the typical angles seen 

 being those of a hexagon. From a photograph by David Fairchild. (Frontispiece.) 



