848 ANNUAL REPORTS OF DErARTMENT OF AGRICULTURE. 



ron( Faction of concrete has progressed favorably and promises use- 

 ful and valuable data. This work will be continued during the 

 current year both in the laboratory and in the field. 



Tn addition to the routine operations of the chemical laboratory, 

 research work for standardizing the tests of bituminous materials 

 and for determining the effect of exposure on various types of such 

 nuUerials has been in progress. 



In the petrographic laboratory quantitative analyses of 85 rock 

 samples, and qualitative anal3'ses of 88 samples, together with chemi- 

 cal and mineralogical analyses of 301 samples, have been made. 



Economic investigations, started in 1910, to obtain reliable infor- 

 mation as to the benefits of improved roads, were continued in 12 

 counties in different parts of the United States. An investigation 

 was also started to determine the amount of bonds issued for road 

 purposes in the various counties in the United States and to develop 

 other pertinent information on this subject. 



An experiment was conducted on an 8-mile stretch of road in 

 Alexandria County, Va., to determine the feasibility of the patrol 

 system in the maintenance of earth roads. 



In order to keep in close touch with road matters, the office has 

 engaged collaborators in 42 States, to report once a month, or when 

 requested. 



The office has continued its policy of cooperation with the railroads 

 in running road-improvement trains throughout the country. The 

 trains were equipped with a lecture car and an exhibit car, wdiich 

 was supplied wnth models from this office. The models were con- 

 structed to represent the various standard types of road and bridge 

 construction. Similar sets of models were loaned to various State 

 fairs and expositions, and lecturers were assigned to accompany them. 

 Experts were also assigned to demonstration trains on the Norfolk & 

 Western and the Missouri, Kansas & Texas Railroads. 



The total number of addresses and lectures delivered by representa- 

 tives of the office numbered 1,135 during the j^ear. In 1911 the num- 

 ber of lectures was 723 and in 1910, 523. The total attendance at the 

 meetings during the past year was 208,472. In 1911 it was 200,000. 



A statement of the different kinds of work performed by the office 

 follows. 



OBJECT-LESSON AND EXPERIMENTAL ROADS. 



The object of the work under this project is to give practical in- 

 struction to local road builders in the standard methods of construc- 

 tion and the use of new materials. This office furnishes at Govern- 

 ment expense, when requested by local officers, one or more engineers 

 to make the necessary surveys, estimates, and specifications, super- 

 vise construction, and give practical instruction. The local authori- 

 ties must furnish all machinery, materials, and labor.^ Before under- 

 taking work in any community the officials having jurisdiction over 

 the road to be improved are required to make application to the 

 office on a form provided for that purpose. During the fiscal year 

 ending June 30, 1912, 32 object-lesson roads were supervised by rep- 

 resentatives of the office, and may be classified according to materials 

 of construction as follows: One plain macadam; 1 plain macadam 

 with oil surface treatment ; 3 gravel ; 7 earth ; 16 sand-clay ; 1 gravel- 

 clay ; 2 bituminous macadam, 1 of which was surfaced with asphaltic 



