30 BULLETIN 670, U. S. DEPAKTMENT OF AGRICULTURE. 
PUBLICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE RELATING 
TO ROAD IMPROVEMENTS. 
AVAILABLE FOR FREE DISTRIBUTION BY THE DEPARTMENT. 
Road Models. (Department Bulletin 220.) 
Portland Cement Concrete Pavements for Country Roads. (Department Bulletin 
249.) 
Progress Reports of Experiments in Dust Prevention and Road Preservation 1914 
(Department Bulletin 257.) 
Methods for the Examination of Bituminous Road Materials. (Department Bulle- 
tin 314.) 
Methods for the Determination of the Physical Properties of Road-Building Rock. 
(Department Bulletin 347.) 
Brick Roads. (Department Bulletin 373.) 
Economic Surveys of County Highway Improvement. (Department Bulletin 393.) 
Progress Reports of Experiments in Dust Prevention and Road Preservation, 1915. 
(Department Bulletin 407.) 
Convict Labor for Road Work. (Department Bulletin 414.) 
Earth, Sand-Clay, and Gravel Roads. (Department Bulletin 463.) 
Results of Physical Tests of Road-Building Rock in 1916, Including All Com- 
pression Tests. (Department Bulletin 537.) 
The Results of Physical Tests of Road -Building Rock in 1916 and 1917. (Depart- 
ment Bulletin 670.) 
Sand-Clay and Burnt-Clay Roads. (Farmers' Bulletin 311.) 
Macadam Roads. (Farmers' Bulletin 338.) 
Benefits of Improved Roads. (Farmers' Bulletin 505.) 
Road Drag and How It Is Used. (Farmers' Bulletin 597.) 
Rules and Regulations of Secretary of Agriculture for Carrying Out Federal Aid 
Road Act. (Circular 65, Office of the Secretary.) 
FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, GOVERNMENT PRINTING 
OFFICE, WASHINGTON, D. C. 
Object Lesson and Experimental Roads and Bridge Construction, 1912-13. (De- 
partment Bulletin 53.) Price, 5 cents. 
Progress Reports of Experiments in Dust Prevention and Road Preservation, 1913. 
(Department Bulletin 105.) Price, 5 cents. 
Vitrified Brick Pavements for Country Roads. (Department Bulletin 246.) Price, 
10 cents. 
Construction and Maintenance of Roads and Bridges from July, 1913, to December, 
1914. (Department Bulletin 284.) Price, 10 cents. 
Relation of Mineral Composition and Rock Structure to the Physical Properties of 
Road Material. (Department Bulletin 348.) Price, 10 cents. 
Use of Split-Log Drag on Earth Roads. (Farmers' Bulletin 321.) Price, 5 cents. 
Road Materials of Southern and Eastern Maine. (Office of Public Roads Bulletin 
33.) Price, 20 cents. 
Dust Preventives. (Office of Public Roads Bulletin 34.) _ Price, 15 cents. 
Examination and Classification of Rocks for Road Building, Including Physical 
Properties of Rocks with Reference to their Mineral Composition and Structure. 
(Office of Public Roads Bulletin 37.) Price, 15 cents. 
Methods for Examination of Bituminous Road Materials. (Office of Public Roads 
Bulletin 38.) Price, 10 cents. 
Road Material Resources of Minnesota. (Office of Public Roads Bulletin 40.) 
Price, 10 cents. 
Physical Testing of Rock for Road Building, Including Methods L T sed and Results 
Obtained. (Office of Public Roads Bulletin 44.) Price, 15 cents. 
Oil-Mixed Portland Cement Concrete. (Office of Public Roads Bulletin 46.) 
Price, 10 cents. 
Descriptive Catalogue of Road Models. (Office of Public Roads Bulletin 47.) 
Price, 15 cents. 
Repair and Maintenance of Highways. (Office of Public Roads Bulletin 48.) 
Price, 15 cents. 
Bitumens and Their Essential Constituents for Road Construction and Maintenance. 
(Office of Public Roads Circular 93.) Price, 5 cents. 
Naphthalene in Road Tars: Effect of Naphthalene Upon Consistency of Refined 
Tars. (Office of Public Roads Circular 96.) Price, 5 cents. 
Progress Reports of Experiments in Dust Prevention and Road Preservation, 1912. 
(Office of Public Roads Circular 99.) Price, 5 cents. 
