118 CONSTRUCTION 



6 weeks, though disintegration of the surface may begin in 

 3 weeks. 



Col. Spencer Cosby describes the use of oil in the 

 Washington parks as follows: 



" All ruts and holes in the surface of the road are first 

 repaired by cleaning out the cavity, filling it with coarse 

 stone, which is covered with a coating of hot, heavy ? 

 asphaltic oil, then sprinkling a light coat of screenings over 

 the oil and finally compacting the mass by ramming. 

 When all holes have been repaired, the surface of the road 

 is thoroughly cleaned with rattan brooms, care being 

 taken to remove all loose materials and caked dirt or dust 

 so that the stone forming the wearing surface of the road 

 shall be exposed and clean. When the road is entirely 

 free from moisture, and during warm, dry weather, if possi- 

 ble, a light asphaltic oil is spread without being heated 

 over its surface by means of sprinkling wagons. One- 

 third to one-half gallon of oil to the square yard usually 

 forms the first application. To allow it to penetrate into 

 the surface, the road is closed to traffic for at least 48 hours 

 after the first application. At the end of this time the 

 surface of the road is covered with a thin coating of clean, 

 coarse, sharp sand or broken-stone screenings, free from 

 dust; it is then rolled and traffic allowed to go over it. A 

 cubic yard of sand or screenings usually covers from 75 to 

 125 square yards of road surface. In this climate and under 

 the conditions of traffic obtaining on our park roads, the 

 oiling treatment described above keeps the surface in 

 excellent condition for a year. It is never dusty and is 

 muddy only when for a few hours after a heavy thaw the 

 skid chains of automobiles tear up the surface. The sub- 

 sequent passage of automobiles without chains soon irons 

 out the roadway. At the end of the year the surface of 



