10 BULLETIN 220, U. S. DEPARTMENT OF AGRICULTURE. 
of the trench, which is then filled with stones from a few inches up to 
8 inches in thickness. 
The cobble gutters (/) show an effective way of carrying away sur- 
face water on steep grades. The stones vary in thickness from 8 to 
12 inches and are laid on a sand or gravel base. They are well rammed 
and given a coat of sand, which is carefully swept in, and tlien the 
stones are rammed again. These gutters are easily cleaned and 
carry the water along rapidly without damage to the road by washing. 
EARTH AND SAND-CLAY ROADS. 
The mileage of roads in the United States is so great and the traffic 
on many of the country roads so light that it will be impossible and 
impracticable for years to come to improve more than a small per- 
centage of the roads with a hard surface. This does not mean, how- 
ever, that all other roads should be neglected. They should, as rap- 
idly as possible, be improved to the extent warranted by their 
importance. The common clay roads may be greatly- improved by 
a little judicious grading and systematic maintenance. 
Frequently, especially in the South, many of the country roads 
may be improved, for all practical purposes, by incorporating sand 
or clay, as the case may require, with the surface soil of the road. 
Thousands of miles of sand-clay roads have already been built in the 
Southern States at an average cost of about $750 per mile. These 
roads meet the present needs of many localities as well as would a 
more expensive form of construction. 
EARTH ROADS. 
Plate V, figure 2, illustrates the construction and maintenance of 
an earth road. 
Section A shows the old and unimproved roadbed. The surface is 
characteristic of altogether too many earth roads. The center is 
lower than the sides, which makes it impossible for the water to run 
toward the ditches; and even if this were possible there are no road- 
side ditches to carry it away. In consequence, the road is usually 
full of ruts and mudholes. 
Section B illustrates a section of earth road under improvement, 
with a road machine or grader. The width of the section shown is 
equivalent to about 33 feet of finished surface from ditch to ditch. 
The use of a reversible road machine is shown in opening roadside 
ditches and in shaping the road surface so that it will shed water. 
The work of this machine is equivalent to the labor of many men, 
and it is done far better than possible with picks and shovels. An 
earth road should have a width of at least 20 feet, preferably 24 to 
30 feet. If the road is narrow, wagons are likely to use the center of 
it and make deep ruts. The surface drainage is provided for by 
giving the road an average crown or slope from center to sides of 1 inch 
