Ftg. 12. 



^ C 



Snowflakes copied from nature under the microscope, and serving 

 to illustrate the geometrical arrangement of molecules of water in 

 crystallizing, a, ^, simple stars; ^, ar', hexagonal plates; <?, /, rays.of 

 large and complex star-shaped flakes. The law of arrangement of the 

 molecules is that of attraction in the lines of three axes at angles of 

 sixty degrees, and the varieties are produced by differences in temper- 

 ature and rate of supply of material. 



■Pst.~ 



