S. DEPARTMENT OF AGRICULTURE, 
- FOREST SERVICE—BULLETIN 92. 
HENRY S. GRAVES, Forester, 
[ LIGHT IN RELATION TO TREE 
oe woes BY 
Se _ RAPHAEL ZON, 
es BA CHIEF OF SILVICS, 
; AND 
HENRY S. GRAVES, 
HOh ESTs 
WASHINGTON : 
GOVERNMENT PRINTING OFFICE 
; 1911. 
