DUST PREVENTION AND ROAD PRESERVATION. 39 
oi the pavement; station 1 1 + 80, 1£ feet by 2 feet, 7 feet from the south 
edge of the pavement; station 12 + 20, 2 feet by 2 feet, 7 feet from 
the south edge of the pavement; station 12 + 48, 3 feet by 3 feet, 
17 feet from the south edge of the pavement; and station 13 + 67, 
I \ feet by 1} feet ; 17 feet from the south edge of the pavement. 
These holes were repaired by first digging out the wearing course 
and base to a depth of 4 inches. They were then filled with 1 J-inch 
stone, and the voids of the stone were partially filled with sand 
and tamped by hand. The refined coal tar referred to in Table 35 
was then applied, covered with f-inch stone, tamped by hand, and 
rolled with a steam roller. 
When inspected in December it was found that two holes about 
18 inches in diameter had worn almost through the thickness of the 
wearing surface. These were located on the north side of the road 
at station 11+6 and station 11+22, respectively. Between station 
I I + 00 and station 1 1 + 50 a bad wavy condition had developed on 
the north side of the road, but only to a slight extent on the south 
side. The center of the roadway was in very good condition. Sev- 
eral of the patches were low and all were in need of a seal coat, but 
the patch made with Topeka mixture was in excellent condition". 
At Hardenbrook Avenue the south side of the intersection was more 
wavy than any other section of the experiments, excepting experi- 
ment No. 2, but the north side of the intersection was in very fair 
condition. 
Experiment No. 6. — Oil asphalt — Penetration method. 
No repairs were made to this section and it continues in excellent 
condition. Two grades of oil asphalt were originally used for a seal 
coat on this experiment, and the relative wearing qualities can now 
be noted. Where the heavier grade of material was used, the seal 
coat remains practically intact and only an occasional stone is visible. 
Many more stones of the wearing course can be seen where the lighter 
grade of the oil- asphalt seal coat was used. 
Experiment No. 7. — Refined coal tar — Penetration method. 
In June this section was in good condition excepting that the fol- 
lowing holes had worn through: Station 15 + 51, 3 J feet by 3 J feet, at 
the north edge of the pavement; station 16 + 90, 1 foot by 4 feet, 1 
foot from the south edge of the pavement; and station 16 + 95, 1 foot 
by 1 J feet, 1 foot from the north edge of the pavement. These holes 
were repaired in the same manner as those in section No. 5. 
In December the section was reported as in good condition except- 
ing for a raveled spot at station 16 + 50. 
Experiment No. 8. — Fluxed native asphalt — Penetration method. 
No repairs were made on this section, and at the December inspec- 
tion it was in good condition. 
