DEW ON CABBAGES. 223 



again rarefied by the heat of the sun, and 

 separated into invisible particles. 



Q. Why is a DEW-DROP ROUND ? 



A. Because every part of the drop is 

 equally balanced; and, therefore, there is 

 no cause why one part of the drop should 

 be further from the centre than another. 



Q. Why is the DEW-DROP on a broad leaf 

 sometimes FLATTENED ? 



A. Whenever two or more drops of 

 dew roll together, they make one large 

 spheroid (or flattened drop). 



Q. Why will DEW-DROPS ROLL ABOUT CAB- 

 BAGE-PLANTS, POPPIES, <&c. without wetting the 

 surface ? 



A. The leaves of cabbages and pop- 

 pies are covered nith a very fine powder ; 

 and the dew-drop rolls over this fine 

 powder, as a drop of rain over dust, 

 without wetting the surface. 



Q. Why does not the drop of BAIN WET the 

 DUST over which it rolls ? 



A. Because it is driven from grain to 

 grain by capillary repulsion. 



Q. Why does not the DEW-DROP WET the 



POWDER Of the 



