342 REPORT AND ESTIMATE. 
come to high, steep bluffs stretching along the river for three hundred and fifty yards. The 
banks for this distance are liable to slide, and it is the only point of the line on this division 
where slides are liable to occur; for the fixed regimen of all the other banks and side hills is 
shown by the forest growth on their sides. These bluffs can be passed by a bridge of a single 
arch, resting on abutments on the fixed river banks at the end of the bluffs, and running along 
the river sides. Ifa slide occurs, it will pass under the arch of the bridge. The next two 
miles is along a plateau ten to twenty feet above the water level, with but moderate excava- 
tions and embankments, when two spurs have to be passed not involving heavy work, and 
requiring, to pass to the plateau beyond, some curvature and side cutting. Then for three and 
five-eighths miles the line with but little curvature can be easily located, when for one-eighth of a 
mile side-hill work will be required, when we come to a prairie which extends along the line 
for three-eighths of a mile, when а sharp point comes down that will require a deep cut or a short 
tunnel. For three-eighths ofa mile side cutting, and for one and a half mile a plateau eight to 
ten feet above the water level, when the river has to be crossed again. The whole fall from 
the second to the third crossing of the river is 20 feet. The line at the crossing of the Bitter 
Root, above the mouth of the St. Regis de Borgia, is two thousand eight hundred and ninety-three 
and one-tenth feet above the sea. 
The materials for construction down the Bitter Root are very abundant. There will be no 
practical difficulty in procuring building stone. There are many navigable reaches of the river 
for boats and scows. Stone can easily be transported by the river to the point where it may 
be needed. Iam satisfied good building stone is to be found at many points on the river and 
in the adjacent country. The bridge could, if necessary, be built of the timber of the country. 
The third crossing of the Bitter Root will be by a bridge one hundred and fifty yards long. 
Banks, gravel on both sides, one to three feet above the highest water. Greatest rise and fall 
of the river, eight feet. The work on this section will be very much less than was stated in the 
report of the explorations of 1853. It was more carefully examined in 1855. 
CROSSING OF BITTER ROOT TO ENTRANCE TO TUNNEL THROUGH THE C(EUR D'ALÉNE MOUNTAINS— 
: DISTANCE 35 MILES, 
In this distance the line rises one thousand and ninety-six and ninety-three hundredths 
feet, reaching an elevation of three thousand nine hundred and ninety and three hundredths 
feet above the sea, and giving an average gradient of thirty-one and four-tenths feet to the mile. 
The gradients in the immediate valley of the river are as follows, on this distance: twelve and 
one-fourth miles, thirteen and three. tenths feet to the mile; three and three-fourths miles, six 
and seven-tenths feet per mile; two and a half miles, forty-three and five-tenths feet to the 
mile; seven miles, thirty-three and six-tenths feet to the mile; two and one-half miles, natural 
grade of the surface sixty-nine and six-tenths feet per mile, to which sixty feet grades can be 
adjusted; two and three-fourths miles, twelve and eight-tenths feet to the mile; one mile, seven 
and six-tenths feet; and three and one-fourth miles, the natural surface is one hundred and 
eight feet to the mile. Sixty foot gradients can be adjusted on this distance by careful side-hill 
location, minimum curvatures, and heavy excavations and embankments; and this will be the 
character of the work for this grade for the last five miles of the St. Regis de Borgia section 
before entering the tunnel, with this exception, there will not be excessive excavations and 
embankments on this section. To avoid excessive curvature, the points in turns of the river 
will have to be sternly dealt with. Nor will there be much rock cutting. There will, however, 
be a great amount of bridging—some considerable structures—as the river must be crossed 
