ORGANIZATION OF THE 
UNITED STATES DEPARTMENT OF AGRICULTURE. 
Secretary of Agriculture Henry C. Wallace. 
Assistant Secretary C. W. Pugsle y. 
D in ctor of Scientific Work E. D. Ball. 
Director of Regulatory Work 
Weather Bureau Charles F. Marvin, Chief. 
Bureau of Agricultural Econom ics 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 Walter G. Campbell, Acting Chief. 
Bureau of Soils Milton Whitney, Chief. 
Bureau of Entomology L. O. Howard, Ch ief. 
Bureau, of Biological Survey E. W. Nelson, Chief. 
Bureau of Public Roads Thomas H. M acDonald, Chief. 
Fixed Nitrogen Research Laboratory F. G. Cottrell, Director. 
Division of Accounts and Disbursements A. Zappone, Chief. 
Division of Publications Edwin C. Powell, Acting Chief. 
Library Claribel R. Barnett, Librarian. 
States Relations Service A. C. True, Director. 
Federal Horticultural Board..'. C. L. Marlatt. Chairman. 
Insecticide and Fungicide Board J. K. Haywood, Chairman. 
Packers and stockyards Administration 1 Chester Morrill, Assistant to the 
Grain Future Trading Act Administration / Secretary. 
Office of the Solicitor R. W. Williams, Solicitor. 
This bulletin is a contribution from 
Bureau of Public Roads Thomas H. MacDonald, Chief 
Division of Agricultural Engineering S. H. McCrory, Chief. 
ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 
10 CENTS PER COPY 
PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
COPY FOR PROFIT.— PUB. RES. 57, APPROVED MAY 11. 1922 
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