6 DEPARTMENT OF AGRICULTURE BULS. 1251-1275 



Fag* 

 Department Bulletin No. 1259. — Standard Specifications for 

 Steel Highway Bridges. — Adopted by the American Association 

 of State Highway Officials and Approved by the Secretary of 

 Agriculture for Use in Federal-Aid Road Work: 1 



Introduction ii 



Division I. Materials 1 



Structural, rivet, and eyebar steel 1 



Eyebars 2 



Steel forgings 3 



Wrought iron 3 



Steel castings 3 



Gray-iron castings 4 



Malleable castings 4 



Phosphor-bronze 4 



Division II. General construction 4 



Steel structures 4 



Painting steel structures 15 



Division III. Design 18 



General features 18 



Loads 20 



Unit stresses 25 



Distribution of loads 26 



Structural steel design 27 



Index 46 



Department Bulletin No. 1260. — Sorghum Experiments on the 

 Great Plains: 



The sorghum belt 1 



Climatic features 2 



Soils 7 



Native vegetation 9 



Sorghum groups and varieties 10 



Experimental methods 11 



Preservation of soil uniformity 11 



Plat technique 11 



Seeding methods 11 



Harvesting methods 12 



Methods of obtaining data 12 



Varietal experiments 13 



Havs, Kans 13 



Chillicothe, Tex 23 



Amarillo, Tex 32 



Woodward, Okla 38 



Lawton, Okla 40 



Dalhart, Tex 41 



Big Spring, Tex 43 



Tucumcari, N. Mex 44 



Northern Great Plains 46 



Summary of varietal experiments 47 



Cultural experiments , 57 



Date of seeding 57 



Rate of seeding in rows 72 



Rate of seeding in close drills or broadcast 83 



Time of cutting sorghum for hay 85 



Literature cited 88 



Department Bulletin No. 1261. — Operating Methods and Expense 

 of Cooperative Citrus-Fruit Marketing Agencies: 



Organization of the exchange system 1 



Harvesting operations and expense 3 



Packing-house operation 6 



Management : 6 



Special operating problems 7 



Careful handling 7 



Standardized grades 8 



Pools and payments to growers 9 



