230 NATURE AND PROPERTIES OF SOILS 



next and the northerly slope last. The amount of heat for 

 a given area is in the order of 106, 100, and 81, respectively. 



Fig. 43. — -Diagram showing the distribution of a given amount of radiant 

 energy on different slopes on June 21, at the 42nd parallel north. 



These generalizations have been established by the work of 

 a number of investigators.^ 



Wollny^ found near Mnnieh that the temperature of south- 



^King, F. H.j Physics of Agriculture, p. 218. Madison, Wis., 1910. 

 ^Wollny, E., UntersucJiungen uher den Emfluss der Exposition auf die 



