ORGANIZATION OF THE 
UNITED STATES DEPARTMENT OF AGRICULTURE. 
u 
Secretary of Agriculture Henry C. Wallace. 
Assistant Secretary Howard M. Gore. 
Director of Scientific Work E. D. Ball. 
Director of Regulatory Work Walter G. Campbell. 
Director of Extension Work C. W. Warburton. 
Solicitor R. W. Williams. 
Weather Bureau Charles F. Maevin, Chief. 
Bureau of Agricultural Economic* Henry C. Taylor. Chief. 
Bureau of Animal Industry John R. Mohler, Chief. 
Bureau of Plant Industry William A. Taylor. Chief. 
Forest Service W. B. Greeley, Chief. 
Bureau of Chemistry C. A. Browne, Chief. 
Bureau of Soils Milton Whitney, Chief. 
Bureau of Entomology L. O. Howard. Chief. 
Bureau of Biological Survey = E. W. Nelson. Chief. 
Bureau of Public Roads Thomas H. MacDonald, Chief. 
Bureau of Home Economics Louise Stanley, Chief. 
Bureau of Dairying C. W. Larson, Chief. 
Office of Experiment Stations E. W. Allen, Chief. 
Fixed yitrogen Research Laboratory F. G. Cottrell, Director. 
Publications L. J. Haynes. in Charge. 
Library Claribel R Barnett. Librarian. 
Federal Horticultural Board C L. Marlatt, Chairman. 
Insecticide and FungicideBoard J. K. Haywood. Chairman. 
Packers and Stockyards Administration (Chester Morrill, Assistant to the 
Grain Futures Administration J Secretary. 
This bulletin is a contribution from 
Bureau of Public Roads Thomas H. MacDonaid. chief. 
Division of Agricultural Engineering S. II. McCrory. Chief. 
28 
additional copies 
OF THI^ PUBLICATION MAY BE PROCURED FROM 
Tin: SUPERINTENDENT OF DO! ' W NTS 
GOVERXMI NT PRINTING OFFICE 
WASHINGTON, 1>. <\ 
AT 
5 I ENTS PEB ( OP"5 
