380 ANNUAL REPORTS OF DEPARTMENT OP AGRICULTURE. 



A representative of the division made a trip tlirough tlie Middle 

 and Northwest States gathering rural-engineering data of all kinds. 



A portable compressed-air spraying outfit was designed for use 

 in experimental work to be conducted by the Bureau of Plant In- 

 dustry. 



Preliminary steps were taken in an investigation to be conducted 

 jointly by this division and the Office of Farm Management to se- 

 cure all available data of an economic and engineering character for 

 the purpose of developing the use of and standardization of farm 

 tractors. 



TRACTION TESTS. 



The field work of the traction tests made to determine the actual 

 effect of road improvement on draft and width of tire was reported 

 last year as completed except for two projects, one in North Carolina 

 and one in Iowa. Neither of these roads has been completed, and as 

 their condition, when completed, will not be uniform throughout 

 the length, the results of final tests would be of little or no value in 

 comparison with those already obtained; therefore it has been de- 

 cided not to make the final tests on these roads. 



An experimental dirt road was built on the Arlington Farm for 

 the purpose of tests to determine the effect of various widths of tires 

 on dirt roads. A preliminary report based on these tests was pub- 

 lished as Secretary's Circular No. 72. 



