REPORT. 
Referring to the accompanying sketch for a delineation of the lines described, I will now 
report on the salient character of that portion of the important forked route to which I have 
repeatedly referred, which extends from Puget Sound to the plains of the Great Basin, and in 
a more general manner on the succeeding sections of the route between the plains of the Great 
Basin and the Mississippi river. 
It will he readily understood that that portion of the route between Puget Sound and the 
plains of the Great Basin is the northern fork or branch of any central railroad to California. 
In. describing the lines of this first portion of the route, I will term the belt of country extend¬ 
ing from Puget Sound to Fort Boise (see sketch) the first division; and that extending from 
Fort Boise, through Snake River valley, to the plains of the Great Basin, the second division. 
From Seattle, on Puget Sound, to a point near the Dalles of Columbia river, all lines are com¬ 
mon to both the northern (that of the 41th and 49th parallels) and the southern (that of the pres¬ 
ent report) routes to Puget Sound. From that point to the approaches of the Blue Mountain 
range on the river line (see sketch) to the Pass of the Walla-Walla, undulating grades of 
thirty-five (35) feet to the mile may be adopted to save work. The actual approach must be 
made at fifty (50) feet. In the continuation of the river line north of the Blue mountains, the 
approaches can be adjusted at forty (40) feet per mile, and some difference of grade be adopted 
to save work. 
By the line from the vicinity of the Dalles, skirting the high country south (to avoid river 
bridges and severe cuttings of low summits near the Columbia) by detour and by “side-hill 
approach,” the first rise from the river valley will probably require grades of not less than fifty 
(50) feet per mile. All work in the vicinity of the valley of the Columbia is of costly character; 
but on reaching the surface of the plateau, at the base of the Blue mountains, grades of thirty- 
five feet may be adopted. All these details of location will be studied in future survey, and the 
line chosen which shall seem best applicable to the summit of the pass and its approaches. 
From the su mm it, of the first Blue Mountain range, the whole country toward the south is 
distinctly visible. The connecting spur between the Blue mountains and the great Cascade 
range, near the source of the Des Chuttes or Fall river, appears perforated by the headwaters 
of that river, and presents a low depression in their vicinity. The line of detour to which I 
have last referred, (see sketch,) rising by the valley of the small stream near the Dalles, and 
skirting the mountain base, would develop some of the richest country in Upper Oregon, and, 
through the pass of the headwaters of the Des Chuttes, could make connexion with a route to 
California, by a descent to the plains of the Great Basin in a due southerly direction. The last- 
named route is not within the province of the present report. A line of such direct southern 
tendency should preferably pass west of the Cascades, and through Willamette valley and the 
gold regions of the coast. 
A descent east from the pass of the Walla-Walla can be made by skirting the valley of the 
Grande Ronde river toward the south, and thence crossing the summit between the Grande 
Ronde and Powder rivers, by a system of curvature approach—the change of direction from a 
tangent of at least one thousand (1,000) feet—and the curvature of mile radii. The descent 
toward the waters of Powder river can be made by skirting the broken country south, (or nearer 
