Exp-lanatory Note 



The series embodies results of invesL-itaia ■.ms, usually of restricted 

 acope^ intended to aid or direct management or utilization practices and 

 as gui-des for administrative or legislative action. It is issued in 

 limited quantities for the official use of Federal^ State of cooperating 

 agencies and in processed form for economy and to avoid delay in publication. 



Washington, D. C, 

 February^ 19^2 



