Explanatory- Note 



The series embodies results of Investigations, usually of 

 restricted scope, intended to aid or direct management or 

 utilization practicss and as guides for administrative or 

 legislative action. It is issued in limitad quantities for the 

 official use of Federal, State or cooperating agencies and in 

 processed form for econoniy and to avoid delay in publication. 



TJashineton, D, C, 

 January 1951 



