BULLETIN 407, U. S. DEPARTMENT OF AGRICULTURE. 
Table 2. — Corrugated metal culverts. 
Material. 
Coppered 
iron, 
station 
-2+00 
Ingot 
iron, 
station 
9+19 
Coppered 
iron, 
station 
9+43 
Coppered 
steel, 
station 
29+00 
Open- 
hearth 
steel, 
station 
74+87 
Coppered 
steel, 
station 
77+99 
Ingot 
iron, 
station 
80+94 
Open- 
hearth 
steel, 
station 
218+96 
Diameter inches . . 
Analysis of metal: 
Carbon. . .per cent . . 
Sulphur, .per cent . . 
Phosphorus, per 
cent 
24 
0.03 
.028 
.0094 
15 
0.03 
.030 
.009 
.015 
.05 
15 
0.03 
.039 
.011 
.016 
.16 
24 
0.08 
.046 
.030 
.37 
.16 
18 
0.06 
.026 
.025 
.32 
.016 
24 
0.09 
.053 
.0105 
.38 
.19 
18 
0.03 
.038 
.012 
.009 
.06 
18 
0.05 
.029 
.027 
Manganese, per cent 
Copper... per cent.. 
.02 
.31 
.016 
Concrete head walls were built for all pipe culverts and a concrete 
gutter was constructed on the right from station 29 + 00 to station 
36 + 18 on a 4.92 per cent grade. 
Four Mile Run Bridge. — It was necessary to build a new bridge 
over Four Mile Kun at station 101+87. The design adopted for 
this bridge was of two 16-foot spans with 16-inch slabs. Work was 
commenced on the bridge March 6 and was finished June 6. The 
total cost was $3,332.56. Fifty-eight yellow pine piles were driven 
to a 20-ton theoretical bearing for the two abutments and the center 
pier foundations, which were built of concrete mixed in the propor- 
tions 1 : 2 J : 5. The foundations were begun 3 feet 4 inches below 
low water. No sheeting was used in the excavation for founda- 
tions and the pits were kept dry by the use of pumps. All concrete 
was mixed by hand on two large mixing platforms and a washed- 
gravel aggregate was used. Concrete for the slabs was of 1:2:4 
mixture, and was reinforced with deformed bars. A railing was con- 
structed of concrete with a mix of 1 part cement to 2 J parts of sharp 
sand. 
All forms were constructed of dressed lumber and thoroughly 
braced. The forms for the bridge rail were oiled and other forms 
were kept wet during the placing of concrete. The rail was given 
three coats of a wash made as follows: 1 pound concentrated lye, 4 
pounds alum, and 5 gallons of water, to which sufficient cement was 
added to make a wash that would spread with a large brush. The 
finished bridge has a clear width of 22 feet. 
Foundation or base course. — On Section I an average interval of 60 
days elapsed between the completion of excavation or rough grading 
and the commencement of subgrade construction and placing of 
gravel base. The subgrade was prepared exclusively by the use of 
picks and shovels, and the work was kept from three to five stations 
ahead of the gravel-base construction. All yielding and spongy areas 
were removed as rolling progressed and fresh material was supplied. 
The gravel base, on this section, had an average compacted thick- 
ness of 6 inches, and was constructed of a sand-clay gravel, which 
