720 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



cost of $iri. As soon MS tlio ^inuiid hnu dried sntficiontly, th<> subgrade was 

 rolled with a 10-ton steam roller. Fiiiriy fjood prnvel was obtained at a pit 

 3,(K)() feet from the road, but it was necessary to screen this };ravel, since it 

 con'alned 40 per cent of tine sand and dirt. The screening was done by hand, 

 and cost, with the loading, 45 cents per cubic yard; hauling from the jnt 

 amounted to 2G cents i)er cubic yard; spreading, 5.3 cents per cubic yard; and 

 sprinkling and rolling. (I cents per sciuare yard. Tlie gravel was applied as 

 follows: A first course, varying in size from 3 inches to one-half inch, was 

 spread to a depth of 7 inches and rolled into place. A second course, varying 

 in size from 1 inch to one-fourth inch, was next applied, and the road was 

 sprinlckxl and rolled until lirni and smooth. Hot asphaltic oil was then applied 

 at the rate of 1 gallon to the sciuare yard, and was followed by a layer of 

 screened gravel, varying in size from 1 inch to one-fourth inch, which was 

 spread uniformly over the entire surface. The road was then rolled with a 

 10-ton roller and a second application of hot asphaltic oil was made at the 

 rate of one-half gallon per square yard. The surface was now dusted over 

 with carefully selected fine gravel ranging from 1 inch to dust, and the road 

 was then rolled until firm and smooth. This treatment was given for a length of 

 2.400 feet. The remaining 1,010 feet were finished without the use of asphaltic 

 oil. The cost of the California asphaltic oil treatment was as follows: Seventy- 

 five cents per 42-gallon barrel at the wells and $1 i)er barrel for freight. Heat- 

 ing, hauling, and spreading amounted to a total of $90.80, making a total cost 

 of 8 cents per square yard for the oil treatment. Other cost items of this work 

 were : Shaping the subgrade, $48 ; labor on the cross drains, $3 ; and repairs, 

 $13.70. 



The total cost of this road to the community was $2,411.30. From this may 

 be derived the following unit costs: Oiled-gravel section, 42.1 cents per square 

 yard, or $3,903 per mile; an<l water-bound gravel section, 34.1 cents per square 

 yard, or $3,209 per mile. These costs were based on a labor charge of $1.50 for 

 nine hours and $4 per day for teams. Seven and one-half tons of fuel wore 

 used, at a cost of $6.85 per ton. The work comprised 4,266 square yards in the 

 oiled-gravel section and 1,795 square yards in the water-bound gravel section. 



ASPHALT-SLAG ROAD. 



Robinson Station, Ala. — ^The section improved here was a portion of the 

 Telegraph Road running north from Mobile toward Mount Vernon. Work 

 began on February 13, 1911, and was completed on February 21, 1911. Three 

 hundred and twenty-five feet of this road were given a macadam surface 16 

 feet wide. The surrounding land is rolling and the subsoil was sandy over 

 the entire section. 



The material used was an asphalt slag donated by a local asphalt company. 

 The slag contained considerable bitumen and was broken by hand in sizes vary- 

 ing from 3 inches to dust. It was black, exceedingly tough, and possessed a 

 rather weak binding quality, which probably could have been Improved by 

 crushing fine and heating. The first course of material, varying in size fi-om 3 

 inches to three-fourths inch, was spread to a depth of 51 Inches and rolled. A 

 second course 2 inches deep, varying in size from three-fourths inch to dust, 

 was then applied. The road was given a crown of one-half inch to the foot, 

 lu this work a 3-ton horse roller was used. 



The total cost of the work was $125.88. which is at the rate of 21.8 cents per 

 square yard, and is equivalent to $204 per mile. These figures are based on a 

 labor cost of $1.50 per day, and team with driver at the rate of $4 per working 

 day of nine hours. The work comprised 578 square yards. 



OIL-MIXED CONCEETE BOADS. 



Washington, D. C. — From .Tune 0, 1910, to June 14, 1910, an oil-mixed con- 

 crete surface, 356.1 feet in length, was laid on Meridian Place, between Center 

 Street and Fourteenth Street. The street is 19.5 feet wide between gutters 

 and has a subsoil of gravelly red clay. All the grading had been done, and the 

 curbs and gutters were in place when this office assumed charge of the work. 

 A foundation of two courses of broken stone was laid. The first course con- 

 sisted of broken stone varying in size from IJ inches to one-half inch, laid 5 

 inches deep. After this bad been rolled with a 12-ton roller, screenings ranging 

 from one-half inch to dust were applied and the surface was finished as in 

 the case of an ordinary macadam road. The wearing surface applied to this 



