ROADS AND PATHS 33 



entire roadbed a heavy mass made of bundles of twigs or 

 branches, each bunch ten inches in diameter and twenty 

 feet long. These bundles are laid one across the other, 

 layer after layer, until the top layer lies transverse to 

 the direction of the road. Usually the ditches at the 

 side of the road are made open. 



The waterways of culverts should be large enough to 

 take the greatest volume of water they will in all prob- 

 ability be required to carry off. Eighteen inches, or, if 

 their shape is circular, twenty inches in diameter will 

 usually suffice for this purpose. Small culverts are 

 often made of slabs or plank, but such methods are 

 shiftless and are not to be commended. 



The drainage of the surface of the road on ordinary 

 , places is generally done ^\^th paving blocks of granite, 

 trap, or asphalt composition about the size of an ordi- 

 I nary brick, set on edge, except that they are made con- 

 I siderably thicker in order to bed them properly. They 

 ■ are laid in sand, and thoroughly rammed do^^^l on the 

 I foundation or metal of the road, which should be in all 

 cases carried across under the entire gutters so as to 

 prevent all chances of the gutters settling. These 

 gutters are usually made fourteen inches, eighteen 

 inches, and two feet \\ide, according to the size of the 

 road. A slightly concave surface should always charac- 

 terize a gutter, but the mistake is often made of hollow- 

 ing them out too deeply. 



It is easy to see that the gutters would be of little use 

 unless they were connected with a complete drainage 

 system, through road basins located twenty-five feet to 

 three hundred feet apart, into drain pipes that ^^^ll lead 

 the water to some general sewer or waterway. But it 

 is naturally asked by many who have moderate-sized 

 3 



