" If gutters are provided, then these stones shall be distributed on a strip two feet in width next to the gutter. This layer of gravel is to be uniformly spread on the roadway, and well moistened. The gravel shall be well rammed for at least one foot from the gutters, should these be paved, or if the gutters are not paved, then one foot from the curb. The remaining portion of the roadway shall then be rolled with a roller weighing not less than 25o pounds to the inch width of tire. The rolling of the roadway shall commence at the rammed portion. All depressions shall be promptly filled, moistened, and again rolled. The sprinkling and rolling must be continued until the surface is uniformly hard, compact, and in such condi tion that it will not yield or cut up under the wheels of a heavily loaded wagon.
Oiling: " Oil shall then be evenly distributed over the entire surface of the roadway, in a volume equal to one gallon, by measure, per square yard of surface.
"Coarse sharp sand shall then be sprinkled over the entire surface of the roadway, until no free oil can be seen.
" After a lapse of not less than twelve hours, oil shall again be evenly distributed over the entire surface of the roadway in a volume equal to one-half gallon, by measure, per square yard of surface.
"The entire surface of the roadway shall again be sprinkled with coarse sharp sand until the oil is completely absorbed, and then rolled with a roller weighing not less than 250 pounds to the inch width of tire until the surface is unyielding. In all cases sufficient sand shall be used to prevent the oiled material from picking up.
"The total amount of oil used shall not be less than one and one-half gallons per square yard of the street surface. In the process of oiling, care must be taken not to soil the curbs or walks. After the oiling of a street has commenced it shall be carried on diligently and continually to its completion.
"Sand used for covering the oil must be distributed in piles along the sides of the street before the oil is applied, and must be spread quickly and in sufficient quantity to prevent the oiled surface from picking up.
"Oil shall not be applied to the surface of a street while it is in a wet condition.
"During and immediately after the rolling, the surface of the street shall be gone over with brooms or rakes and all irregularities removed." The construction of macadam streets in Riverside, California, is described by City Engineer A. P. Camp bell as follows: "Prepare the road-bed and make a regular macadam pavement. Instead of finishing with the ordinary coat of screenings, coat the surface with liquid asphalt, about to gallon to the square yard; then spread about - inch of screenings over the asphalt to act as an absorbent, apply another gallon of asphalt, coat this again with screenings and roll for final.
"This asphalt surface acts as a waterproof coating and prevents the raveling of the surface.
"You will note that I use the words `liquid asphalt;' that is what our road oil is in fact, and the word oil is a misnomer. We specify an oil of 'of Baume, con taining 8o per cent by weight of `D' grade asphalt."