48 



WINDBREAKS. 



2 / O / 2 



tUNQHAttD 3 ICCHA/tOf 



DIAGRAM 18. Protective efficiency of cottonwood row. Natural density. For wind velocities of 5 

 10, 15, and 20 miles per hour. Average height, 50 feet; 100 readings. 



fQQ 



3456789 

 W/NOBftEAK EXPffESSEQ /A/ TERMS 



LEEWA/tO 



DIAGRAM 19. Protective efficiency of cottonwood belt. For wind velocities of 5, 10, 15, and 20 

 per hour. Height, 70 feet; width, 100 feet; 83 readings. 



