(160) underlies this whole district, in a bed varying from a few inches to six feet thick, and is a source of fuel not to be overlooked. Lime and sand are both to be obtained, and good materials for brick exist. In summer there is a scarcity of water, the small streams being dried up; but from the elevation of the plateau above the valley, a good means is afforded of keeping up a supply, with the assistance of reservoirs, in those places at a distance from the main stream.

The rise in level along the Missouri is about one foot, and on Milk river about three feet, per mile only.

The cottonwood of the Missouri will answer temporarily for railroad sleepers. The stockade built of it at Fort Union, which does not rest on the ground, is firm and sound, though built over 25 years ago. Milk river is crossed in a bend of the stream, at right angles to the current, requiring a truss of about 240 feet, with an abutment 20 feet above the river bottom. The masonry should be protected by piling from the wash of the freshets.

CROSSING OF MILK RIVER TO FORT BENTON.

Milk river is crossed about two miles below the mouth of Box Elder creek, and the line passes up its general valley about thirty miles, when a choice of routes maybe made. One route passes up a wooded tributary of the Box Elder, thence over a low divide to the Missouri, and follows up the Missouri, on its northern bank, to Fort Benton. The other ascends the plateau between the Box Elder and the Marias, passes near the spring, descends into the valley of the Marias, near the junction, with the Téton, continues up the Téton to the point where it approaches within one hundred yards of the Missouri, then passes to the valley of the Missouri, and continues on the route before referred to, to Fort Benton. The distance by the first route is eighty-one and one-half miles, and by the second, seventy-five and five-tenths miles. The grades up to Box Elder will range from ten to twenty feet. The excavations and embankments will be quite moderate. The several streams, which are from five to ten miles apart, will require bridges of from fifty to seventy-five feet in length. There are also coulées which will require some culvert work. The valley of the Missouri should be struck at the mouth of the stream which flows from the springs; the distance from Box Elder creek to this point being twenty-one miles. About five miles from this point will be the summit of the divide, which, allowing for a cut of fifty feet, will have an elevation of 2,832.2 feet.

The altitude of the Missouri is 2,558.5 feet, requiring a grade to meet the Missouri of 54.74 feet to the mile. From the Box Elder to the summit the grade will vary from 45.6 feet to 48.2 feet per mile. Most of this distance is a gently rolling plateau, requiring but little excavations and embankments; but the first four miles from the Box Elder the grade will be 45.65 feet to the mile, with some heavy work. From the mouth of the creek to Fort Benton, a distance of thirty and one-half miles, the grades will be very gentle, not exceeding ten feet to the mile; the whole rise being but 221 feet. In that distance, to avoid sharp curvature, say less than two thousand feet radius, there will be heavy excavations in turning the points which project into the river. The river is wide, and will render it perfectly easy to waste earth without interfering with the channel of the river.

The altitude of Milk river is 2,388.8 feet, and of the Box Elder, at the point where the route leaves it, 2,691.7 feet. The other line referred to, passing over the plateau, in four miles makes a height of 2,924.3 feet, when it continues over a gently rolling prairie for twenty-six miles to the point where the descent commences to the valley of the Marias, the highest point being in the vicinity of the springs, and having an altitude of 2,982.2 feet. The descent to the Marias involves difficult and costly work, and must be made in one and a half miles along the foot-hills, and up the stream, which should be crossed by a bridge one hun-

(161) dred feet high, at an altitude of 2,782.9 feet, the altitude of the point whence the descent commences being 2,865.1 feet. The route then continues up the Téton nine and a half miles to the Cracon du Nez, with a descending grade of 31.7 feet to the mile. The bluffs of the two sides of the Cracon du Nez are about one hundred yards apart, the foot of the bluff in the Téton being 81.5 feet above the foot of the bluff on the Missouri. By commencing a cut, however, before reaching the bluffs, we reach the valley, and commence going up the Missouri with an embankment about forty-one feet above the immediate line of the river, but which can be very much reduced by being adjusted along some foot-slopes that line the valley. The descent can be made to the valley by a grade not exceeding forty feet to the mile, without heavy excavations or embankments. By either of these routes there will be no difficulty about supplies of water. The Box Elder, its several tributaries, the Missouri, the Marias, and the Téton, will furnish an unfailing supply. The longest distance without water will be on the plateau route, viz: from the Box Elder to the Marias, a distance of 31.5 miles; it is probable, however, that water can be obtained by sinking wells near the springs. Either route can be easily supplied with all the materials for construction. The Bear's Paw, near by, as well as the country south of the Missouri, will furnish timber of all kinds. There is good limestone and sandstone in the vicinity of the route; sand for mortar, and clay for bricks.

FORT BENTON TO ENTRANCE TO TUNNEL—CADOTTE'S PASS.

Cadotte's Pass, at the head of the Big Blackfoot, may be reached from Fort Benton, either by keeping up the valley of the Missouri to the mouth of Sun river, thence up the Sun to a point nearly opposite the Rattlers, thence crossing the Sun between Crown Butte and the Rattlers, and continuing nearly on the course pursued by the wagon road, or the crossing of the Sun may be made by ascending the plateau from Fort Benton, and passing by the springs and Prairie lake, referred to in the itinerary. The distance by this latter route, from Fort Benton to the entrance to the tunnel of Cadotte's Pass, will be one hundred and two and two-tenths miles. This is four miles longer than the trail pursued in 1853, for I have allowed two miles to make the descent into and the crossing of Sun river, and two miles for that of the Dearborn. The distance from Fort Benton to the crossing of Sun river will be fifty-five and one half miles; thence to the Dearborn, thirty-six and seven-tenths miles; thence to the entrance to the tunnel, ten miles. From Fort Benton to the springs the distance is sixteen and one-fourth miles, to the lake, eighteen and one-half miles, and thence to the Sun river, twenty and three-fourths miles.

There will be no difficulty in adjusting grades over this distance not exceed-ing forty feet to the mile. The highest summit, at a distance this side of the Prairie lake of seven and three-quarter miles, is three thousand eight hundred and thirty-six feet above the level of the sea. There is a summit five and a half miles beyond the Prairie lake, whose altitude is 3,702 feet above the sea. The altitude of the Prairie lake is three thousand five hundred and fifty-eight feet. To adjust, however, a grade of forty feet, there will have to be cuts through the several summits, and excavations and embankments throughout the route. Sun river should be crossed with a bridge fifty feet above its valley, and the descent must be made with much care by side-hill locations, for in fifteen and three- fourths miles, there will be a descent of three hundred and sixty-six feet. The Dearborn is crossed about a mile and a half above its junction, with the stream flowing from Cadotte's Pass, with a bridge seventy feet above its immediate valley, and at an elevation of four thousand three hundred and forty feet. There is a high ridge five and six-tenths miles beyond the crossing of Crown Butte creek, and twenty miles from Sun river, where a tunnel will be required half a mile in length. This ridge has an elevation of four thousand two hundred and

(162) thirty-five feet above the sea, and the summit level of the tunnel will be four thousand and seventy-two feet. The grade, on the supposition that it will be uniform from Sun river to the tunnel, will be forty-four feet per mile, but the work will be difficult, and it will not probably be found practicable to dispense with less than sixty feet grades.

From this tunnel to the Dearborn there will be a rise in the whole distance of two hundred and sixty-eight feet, giving grades, on the supposition that they are uniform, of sixteen and a half feet to the mile. From the crossing of the Dearborn to the entrance to the tunnel is a distance of ten miles, requiring grades of sixty feet to the mile. This work will be very costly and heavy, and require a very careful side-hill location. Besides heavy excavations and embankments, there will be a great number of small bridges and culverts. The eastern mouth of the tunnel will be in the debouche of a ravine, which gives a much better approach than the usually travelled trail. The tunnel will be 4.19 miles in length, when there will be a cut commencing fifty feet deep, and coming out into the valley of the Blackfoot five hundred and fifty-eight thousandths of a mile west of the tunnel. The cut and the tunnel have a grade of sixty feet to the mile. The highest point of the road, therefore, will be at the entrance of the cut, at an elevation of five thousand one hundred and ninety-five feet above the sea, and eight hundred and forty-nine below the mountain summit.

The entrance of the cut will be two and nine hundred and forty-eight thousandths miles west of the western base of the mountain, which is five hundred and sixty-seven feet higher than the eastern. This section, from Fort Benton to the entrance to the tunnel is in the near vicinity of materials for construction; there is good building stone near the crossing of the Sun and Dearborn rivers and near the Crown Butte creek. The Téton. Sun, and Dearborn rivers furnish sand and gravel as well as good cottonwood. The Missouri and the mountains in the vicinity of the pass will furnish the yellow and pitch pine. Cadotte's Pass can be reached more readily on this route than by going high up Sun river, crossing over to the Dearborn, and over the broken country, lying between the Dearborn and the entrance to the pass.

The route by the Missouri to the crossing of Sun river will be easier in its grades than that over the plateau, but it will be heavier work of excavation and embankment. There are many sharp points running down to the Missouri, which must be dealt with in the same manner as the similar places which occur below Fort Benton. The distance will be sixty-three miles, or seven and a half miles further than the route over the plateau. There will be, however, advantages on the line of the Missouri in the unfailing supply of pure water, and its greater accessibility to all the materials of construction.

To reach Lewis and Clark's Pass either of these routes may be taken to Sun river, when we continue up Sun river, and its Elk or south tributary, a distance of forty-eight miles, or ten miles above the forks. The valley of the Sun river and that portion of the Elk fork is very easy for railroad construction, and the grades will vary from 43.5 feet to 50.3 feet per mile. Starting from Fort Benton we make a rise in eleven and a half, twenty-five, sixteen, twenty-two, fifteen, ten and a half miles, respectively; eighty-three, one hundred and sixteen, four .hundred and ninety-five, one hundred and eighteen, one hundred and ninety-seven, three hundred and twenty-five and one tenth feet, giving the respective gradients of seven and twenty-one hundredths, four and sixty-four hundredths, thirty and nine tenths, five and thirty-five hundredths, thirteen and one tenth, thirty and nine tenths, forty-five and six tenths feet, to the mile. At the Great Falls of the Missouri, where in fifteen miles there is a fall of three hundred and fifty-seven feet, the grade must be adjusted with great care, at the expense of heavy work. For ten miles above the forks of Sun river the grade will vary from forty to fifty feet per mile; the work of excavation and embankment will be light. Thence to the tunnel of Lewis and Clark's Pass is nineteen and one

(163) hundred and twenty-one thousandths (19.121) miles, all very difficult and heavy work. The tunnel itself is two and one hundred and twenty-nine thousandths (2.129) miles in length. The summit level of the tunnel is at a debouche a half mile west of the western base of the mountain, and is 5,698.6 feet above the level of the sea. It passes out on a descending grade of sixty feet to the mile, at an elevation of 5,570.86 feet above the sea, the summit level of the mountain being 6,519.3 feet above the sea. As in Cadotte's Pass, the eastern approach is by a ravine north of the travelled trail. In ten miles above the forks the line leaves the general valley of the Elk Fork, crossing the highest summit about half-way between the route of the party of Stevens in 1855 and Hart mountain, and crosses Dearborn river at an elevation of 4,994 feet above the sea, and about one mile above the trail. The country is lower and less broken by this route than in any other part of the plateau between the upper waters of the Sun and Dearborn rivers. The Dearborn itself leaves the mountains by a gap in a direction nearly east, when it turns suddenly to the south, and continuing on three miles it runs suddenly again to the east to the point where it crosses the trail. The railroad line follows along the Dearborn in this south line three miles, and makes the crossing just below its last turn to the east. A bridge, one mile in length and nearly 300 feet above the valley, which at this point has an elevation of about 4,700 feet above the sea, will be required to cross the Dearborn. Thence for two miles and three-eighths the road will follow very nearly the natural grade, varying from forty to sixty feet to the mile. In two miles and three quarters further we come to a ravine, in which flows a stream of water which can only, be turned by continuing up the ravine and keeping closely along the side-hills. Between this point and the entrance to the tunnel, a distance of 4 3/4 miles, there will be seven small streams to cross, involving the adjustment of a grade of sixty feet to the mile, the necessity of constant curvatures with radii of 1,500 or 2,000 feet. There will be very heavy embankments required to cross these several streams, which can, however, be made up from the adjacent spurs, with hauls exceeding in no case a half-mile; moreover, the ravine into which the tunnel debouches on the east, by the best system of side-hill approach, must be filled up, which can be done by the debris from the tunnel. The country at right angles to the line of the road rises towards the mountain at a grade of from one-fourth to one-eighth. This is equally the case with the ravines in which the streams flow and the intermediate divides. Debouching from the tunnel on the western side the line continues in the valley of the stream for five miles, at a grade of thirty-five feet, with an excavation and embankment almost entirely along the natural surface, and for a mile and a half further, at a grade of forty-four feet to the mile, when we leave the stream, and making a cut through a low divide of about 700 feet in length, come upon a gently sloping prairie, down which it can be laid, and brought into the valley of the Big Blackfoot through the open valley of a small stream, at a grade of from sixty to sixty-five feet to the mile. This grade will involve closely hugging the side-hills which line the valley of the small stream, and the Big Blackfoot on the west, and will involve a curve of the minimum radius. The greatest depth of the cut will be 134.7 feet. For the first 80 feet the cut will be from 134.7 feet to 122.6 feet in depth, and for the next 500 feet from 122.6 to 38.8 in depth, then in 100 feet the cut reduces to 31.4 in depth, and in 1,000 feet further to 20.8 feet in depth, and it runs out 200 feet further.

To resume the line down the Blackfoot from Cadotte's Pass. From the summit level at the entrance to the tunnel the line continues down the valley for six and twenty-eight thousandths miles, when it is joined by the line from Lewis and Clark's Pass. Three-fourths of a mile before reaching this point it crosses the stream flowing from the pass; continuing for four and one-fourth miles further, it crosses Lender's Fork. A considerable bridge will be required here, consisting of a single arch of two hundred feet. Excavations and em-

(164) bankments will average from fifteen to sixteen feet. It then continues down the valley, which has been gradually widening from the pass, for nine miles, when it reaches what is known as the cañon. In this distance two streams are crossed coming from the north. This distance is in the prairie known as the Belly. The work here will be very moderate, the excavations and embankments small. The cañon is a low, open valley, in no case less than one-third of a mile in width, and widening out two or three miles. Excavations and embankments are moderate. The country is mostly wooded. Seven miles from the entrance to the cañon we come to a prairie of one thousand acres, which is overflowed at high water, and against which special precautions will have to be made. Only one stream of any consequence is crossed-about three miles before issuing from the cañon. Leaving the cañon, we come into the Stevens prairie. At this point the Blackfoot will have to be crossed twice in a distance of a mile and a half. The distance across the prairie is thirty four and six-tenths miles; and the line can be laid in nearly a straight course by adapting the grade to the ground, at the expense of heavy excavations and embankments. In about eight and a half miles Salmon Trout creek is crossed, requiring a bridge and careful adjustment of line. In ten and a half miles further another large stream is crossed; and in the remaining distance two or three small streams will have to be bridged; and seven miles before reaching the end of the prairie a cut must be made through a low ridge.

We have now come to the lower cañon of the Big Blackfoot. This cañon is nineteen miles long, and is perfectly practicable. The river must be crossed frequently, not, probably, leas than thirteen times, and, to avoid short curvatures, there must be heavy excavations, mostly in rock. Embankments will be moderate. There will be no difficulty in wasting earth. Occasionally sustaining walls must be resorted to. In the narative reference has been made to the prairies opposite projecting points; and in locating the railroad line care must be taken to pass from prairie to prairie. In six miles further we come out of the valley of Hell's Gate into the general valley of the Bitter Root at a place known as the Hell's Gate Ronde. Here the trail crosses the Hell's Gate to Fort Owen. This point, in the estimate, has been called the crossing of Hell's Gate. In this section, of ninety-one and sixty-eight hundredths miles from the tunnel, there will be ample materials for constructions of all kinds; timber for all purposes of construction inexhaustible; ample supplies of water, gravel, and sand are found at convenient points. There are many localities of good building stone. Slate is found at the mouth of Salmon Trout creek, and limestone, suitable for walls of all kinds, in the lower cañon.

The whole descent in this distance is 1,735.8 feet, or an average grade of 18.94 feet to the mile. The several grades shown on the profile, on the supposition of uniform grades, for the several distances will vary from 63 feet to 3.1 feet to the mile. But it will be found advisable, to diminish excavations and embankments, not to use as low grades as three and one-tenth feet to the mile; though without large excavations and embankments and proper aide-hill locations, there will be no necessity of rising grades greater than fifty feet to the mile. It is probable that a better line can be found by turning to the south seven miles before reaching the western end of the prairie, crossing the Big Blackfoot, passing through the extensive Camass prairie on the southern aide, and returning to the immediate valley of the river six miles before reaching the end of the cañon. There will be no difficulty from freshets in this section. The prairies are not overflowed in high water, except small portions of the Belly prairie, and the greatest rise and fall of the Big Blackfoot will be about six feet,

(165) HELL'S GATE CROSSING VIA CLARK'S FORK TO THE SPOKANE.

The route is the same with the route of Stevens of 1855 for seven and a half miles below the Hell's Gate crossing, when it follows the northern foot-slope of the Hell's Gate Ronde, and passes over the summit, which lays between it and the Flathead river, with a gradient of thirty-five feet per mile, or, allowing for errors in the barometer, forty feet. Having attained this summit it strikes a tributary of the Jocko, and descending along that stream to the valley of the Flathead, the gradient being at forty feet, (assumed at fifty,) down the tributary of the Jocko, and down the main streams, as well as down the Flathead to its junction with the Bitter Root, twenty feet. By the barometer the average fall of Clark's Fork is about eleven feet per mile. The road is estimated to descend at a gradient of from fifteen to twenty feet per mile. After leaving the Jocko the road should follow the hills on the left side of the Flathead to a point seven miles above its junction with the Bitter Root; then crossing, it would follow the right bank of Clark's Fork as far as Big Rock; here it would cross, and, following down the left bank, would recross at the Cabinet. Then, tunnelling the Cabinet mountain three hundred yards, it would continue on the right of the river to Lake Pend d'Oreille, and on the northern side of that lake to its lower extremity. Both along Clark's Fork and the lake fifteen feet is about the difference of high and low water mark, and the road must therefore keep the sides of the hills, in some instances requiring high embankments. The tunnel at the Cabinet mountain would be through a formation of which fifty per cent is rock, this being basaltic trap. The transit from Clark's Fork to the Spokane could be made with gradients of not more than twenty-five feet. It might be facilitated by making use of the valley of a small stream which empties, into Clark's Fork, about twelve miles below the lake, and by a valley seen ten miles west of Clark's Fork, which appears to make into Coeur d'Aléne prairie. A bridge half a mile long would be required to cross Pack river. Excellent timber and good stone are found along the whole of this distance.

The crossing of the Spokane will not involve heavy work of bridging, excavation, or embankments; beyond, over the great plain of the Columbia, there are many practicable lines. But to resume.

HELL'S GATE CROSSING TO CROSSING OF BITTER ROOT, DISTANCE SIXTY-FIVE MILES.

Hell's Gate crossing is about three thousand three hundred and fifty-nine feet above the sea. The line, for ten miles and a half, crosses diagonally the Hell's Gate Ronde. There are several small streams and swales in this distance. Excavations and embankments moderate; grade 30.5 feet to the mile. Here a stream is crossed, and continuing down on the east side of the Bitter Root for sixteen miles, through, for nearly the entire distance, a wide, open valley, the Bitter Root is crossed. The line follows the west side of the Bitter Root over a broad and extensive prairie, partially wooded, when it recrosses the Bitter Root, and, continuing on its east side for thirty-one miles, crosses it for the third time just above the mouth of the St.Regis d'Borgia. In the above distance of sixteen miles, before making the first crossing of the Bitter Root, the work of excavation and embankment will be very light for about six miles, when a deep cut must be made through a ridge of rock. In three-quarters of a mile there is a deep re-entering of the river-a sort of delta formed by two streams, three-fourths of a mile apart. An embankment, forty feet high, and two bridges will be required to cross this place, and there will be curvature at both extremities of the embankment. Before reaching the crossing there will be a considerable rock excavation. The total descent in this distance is 1,465.3 feet, giving a grade of 22.5 feet to the mile.

(166) To avoid excessive excavations and embankments, grades of forty feet should be adjusted to the ground, and considerable curvatures must be allowed.

The point of crossing the river is at a turn where a bridge, two hundred feet long, can be thrown nearly at right angles with the course of the stream without involving excessive curvature. The banks are only about fifteen feet high. Suitable building stone can be obtained in the immediate vicinity. After crossing, the line follows the next bank, over a low plateau under a side-hill, for about one mile and a quarter, when it comes round a point of rocks, involving a very heavy excavation, almost exclusively in rock, and there will be a very heavy excavation in rock for a mile and a half further; then a marsh has to be crossed, requiring an embankment of twenty feet. The remaining four and a half miles, before recrossing the river over the partially wooded plateau referred to, will also require, in places, large excavations and embankments. The plateau rises in terraces of from ten to twenty feet in height, and some curvature will be necessary, and an undulating grade, not, however, exceeding thirty feet to the mile.

The second crossing is of the same character as the first; about the same length of bridge and the same direction in reference to the course of the stream. The banks are forty feet high. The fall in this distance of seven and a half miles is 86.3 feet, and the average grade 17.5 feet. Continuing over on the east side of the Bitter Root the line follows, for eight miles, near to, or along the immediate banks of, the river, at from forty to eighty feet above the water level; or the same point could be reached by the line leaving the river in two and a half miles, and crossing in one mile a low point in a spur which runs in a northwest and southeast direction, involving a short tunnel, or deep cut, of about five hundred yards. The first mode is preferable. For five-eighths of a mile further the line will run along the water's edge, there being the whole distance a steep ridge of rocks, with broken stone at the base and partially up the slope. Trees are, however, growing out of the fissures of the rocks. Care must be taken to adjust curvature in this distance, and at two places the line must be built in the water. It will not interfere with the water way. For three and one-eight miles further the line follows the plateau, two streams in this distance requiring inconsiderable bridges. This plateau is thirty to seventy feet above the river. Then one-eight of a mile side-hill work; curvature fifteen hundred feet. Then comes a beautiful partially-wooded prairie for four and one-fourth miles. Excavations and embankments moderate. There will be half a mile of side-hill work during the next two miles. We then cross a fine mountain stream, and come to a plateau again, for three and three-fourth miles, with terraces, as described in the plateau on the west bank of the river; and situated in a large re-entering. For one-half mile some side cutting, when a stream is crossed ; and continuing up a plateau about thirty feet above the water level of the river, for half a mile, we 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 regime 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 mooning along the river side. If a 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 excavations 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-eight 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 a sharp point comes down that will require a deep cut, or a short tunnel. For three-eighths

(167) of a 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 twenty feet. The line at the crossing of the Bitter Root, above the mouth of the St. Regis 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 practicable 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. 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, ten to fifteen feet above the highest water. Greatest rise and fall of the river eleven feet.

CROSSING OF BITTER ROOT TO ENTRANCE TO TUNNEL THROUGH THE COEUR D'ALÉNE MOUNTAINS—DISTANCE THIRTY-FIVE 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 a 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 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 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 obliquely. A single arch will always be sufficient. It will sometimes be necessary to resort to side walls. The trail crosses the river forty-four (44) times. The number of bridges will be much less; several tributary streams to be bridged; much culvert work; road bed to be well raised. The valley is not subject to overflow; the banks are four to eight feet above water level;. several places covered with water at its highest stage. Greatest rise and fall near the mouth of the St. Regis Borgia about five and a half feet; sixteen miles higher up, four feet. There will be considerable wood to cut through and much gravelling. The wood will generally be a small growth in the river bottoms. The materials for construction will be literally inexhaustible. Good limestone was observed at several points, especially about midway of the section.

TUNNEL AT SOHON'S PASS OF THE COEUR D'ALÉNE MOUNTAINS.

This tunnel will be one and three-fourth mile, in easily worked limestone and earth. It passes from the Coeur d'Alene to the St. Regis Borgia in a south by east course, making nearly a right angle with the general course of the road.

(168) The summit is at the eastern debouche, at an elevation of 3,990.03 feet above the sea. It descends to the west at a gradient of sixty feet to the mile, and its elevation on the western extremity is 3,877.7 feet above the sea. The summit level of the divide on the usually travelled trail is 5,089.7 feet.

ROAD TO COEUR D'ALÉNE MISSION—DISTANCE FORTY-EIGHT AND A HALF MILES.

In this distance the line falls 1,556.9 feet to an elevation of 2,290.0 feet above the sea, and giving an average gradient of 32.74 feet to the mile. The grades along the immediate valley of the river are as follows:

For the first 10 1/2 miles from the tunnel the road must be very carefully located along the side-hills north of the river to use sixty feet gradients. The side-hills run gently to the river. There is a narrow, open valley for two and a half miles to the point where the trail crosses the river to pass over the divide, and for four and a half miles further the route is through wood, sometimes of small growth. In this distance three streams are crossed. The next nine miles will require great care in location. The trail passes over low side-hills north of the river, and in some cases a mile from it; and these side-hills come well down to the river, in some cases with a steep slope. The excavations and embankments will be large, and in some instances sustaining walls will be required. Four streams, and several places where water runs in the spring, occur in this distance. Crossing then a low place for three-fourths of a mile there are two sloughs. The road passes through a very heavy growth of cedar, and in one-fourth of a mile reaches the point of junction with the trail over the mountain to the south of the Coeur d'Aléne river. Here a stream comes in from the south. In the next six miles the Coeur d'Aléne is crossed on the trail six times, but the road can be located without crossing the river more than half that number of times. Thus far, except in the low places and forest of cedar referred to, the river does not overflow its banks. The next thirteen miles the river is crossed sixteen times on the trail, nine of which are within the distance of two and a half miles, and in the remaining eleven miles it is crossed but twice. In these last two distances of twenty-four miles there are sections where the road will pass over wet and marshy places. There will be some, though not excessive, rock cutting. The whole section, from the tunnel to the mission, will have a large amount of bridge and culvert work. The bridges will, not be difficult or costly structures, but frequently they must run quite obliquely to the course of the river to avoid short curvature. The bridges may be wooden structures. The mountain pine in the vicinity will furnish abundant material for this and all other purposes of construction. There is good building stone at several localities, limestone up the stream and slate lower down; gravel, sand, and clay occur at convenient points. The highest rise and fall of the river is four feet.

(169) COEUR D'ALÉNE MISSION TO CROSSING OF COLUMBIA—DISTANCE 181 3/4 MILES.

The line keeps north of the Coeur d'Aléne river and lake, and crossing the Spokane, or, more properly speaking, Coeur d'Aléne near the eastern edge of the Coeur d'Aléne prairie, passes in nearly a straight direction to the main Columbia, near but above the mouth of the Yakima. The line could keep still further down the Coeur d'Aléne and Spokane to a junction with the railroad line reported practicable as the results of the explorations of 1853-'54. The route described above is unquestionably practicable, the whole country having been under view; but great care will be required to locate a crossing of the river, and to gain the plateau beyond; for there are spurs running down from the south to the Coeur d'Aléne river and lake which have to be turned.

But between the river and Hangman's creek there is a divide which will have to be surmounted, and corresponding to the ridges found in other parts of the great plain.

The distance from the mission to the crossing of the Coeur d'Aléne is twenty seven miles. There will be much heavy work on this distance, considerable curvature and some rock excavation. The route, after leaving the mission two miles, will pass through a rolling and wooded country interspersed with prairies for about eighty miles. The remaining distance to the Columbia is destitute of timber, a distance of about one hundred miles. Except for this portion, timber, wood, building stone, sand, clay, and gravel, abound for purposes of construction. For the portion destitute of timber the supply must come from the extremities.

The Upper Columbia will furnish an inexhaustible supply. There is no danger of a deficiency of water, as there are many streams and lakes along the route.

The fall from the Coeur d'Aléne mission to the crossing of the Spokane is about one hundred and ninety-eight feet in thirty miles, giving an aggregate grade of six and three-fifths feet to the mile; and from the crossing of the Spokane to the crossing of the Columbia, fifteen hundred and ninety-eight feet in one hundred and fifty-one and three quarters miles, or an aggregate gradient of ten and a half feet to the mile. But there will be several summits in this distance and a maximum summit of about two thousand six hundred feet above the sea. It is not probable that gradients exceeding forty to fifty feet to the mile will be required along this distance.

CROSSING OF THE COLUMBIA TO SEATTLE, ON PUGET SOUND—DISTANCE 220 MILES.

The Columbia river for fifteen miles above the mouth of the Yakima is four hundred yards wide, with sand and gravel banks thirty feet high. The railroad line passes up the valley of the main Yakima to the Snoqualmoo Pass, where there are two routes for travelling through the divide, one being by a route south, and the other by a route north of Lake Kitchelus. The first brings the line to the valley of the Nooknoo or Cedar creek, which can be followed down to its junction with the stream flowing from the Dwamish lake to the Dwamish river, near the outlet of the lake. The line then runs in nearly a straight course to Seattle; or following down the Nooknoo twenty-nine miles and a half, the line may take the summit and the northern slope of the low ridge separating Lake Mowee from the valley of the Snoqualmoo, and from that taking a spur running from the Nooknoo Falls to those of the Snoqualmoo, reach the latter falls at a distance of forty-five miles from the tunnel; thence the distance to Seattle is thirty miles, and the grades do not exceed twenty feet. The route north of Lake Ketchelus comes immediately upon the waters of Snoqualmoo;

(170) and although no observations have been taken for altitude, intelligent gentlemen who have been over both routes state that it is lower and involves less tunnelling than the route south of Lake Ketchelus.

There are two modes of piercing the mountain south of Lake Kitchelus: First, by means of a tunnel four thousand yards in length from the level of Lake Willailootzas, two thousand nine hundred and ninety-three feet above Vancouver; second, by a tunnel eleven thousand eight hundred and forty yards long from the level of Lake Kitchelus, two thousand three hundred and eighty eight feet above Vancouver. The average grade to the Snoqualmoo Falls, with the use of the long tunnel, will be forty-six and three-tenths feet per mile; and with the use of the short tunnel fifty-nine and eight-tenths feet per mile.

The ascent up the valley of the Yakima is as follows:

From the crossing of the Columbia to the commencement of the pine timber is a distance of ninety-six miles. The general character of the valley to this point is wide, open, and terraced; the ground of sand, gravel, or loose stones; but little clay or vegetable mould; curves easy; long stretches of straight road perfectly practicable. In this distance there are five points where the hills come close to the river, making, at most ten miles of side cutting necessary. This cutting is generally in earth, loose stones, or trap rock, easily broken into blocks. In addition to these five points, the last eight miles of the ninety-six will be principally side-cutting in earth, gravel and sand; the work light, and no very high slopes. In the first eighty miles from the Columbia the grade will be twelve and a half feet to the mile; in the last sixteen miles it will be 8 1/2 feet to the mile. By keeping thus far the north bank of the Yakima, the only bridges of any consequence will be two, over streams each about seventy feet in width.

At some place in this vicinity it would be advisable to cross to the south bank of the Yakima, which is here about forty yards wide; good crossing easily found; plenty of timber on the spot; stone for masonry within twenty-five miles by water. The road now keeps to the valley twenty-one miles further on, four miles beyond Ksitkas, passing through open pine woods; soil light, sometimes gravelly; about two miles side-cutting; grade eight feet to the mile. If the short tunnel be used the road at this point must leave the valley, take a side location on the northern slope of the mountains bordering the valley on the south and ascend eight hundred and ninety-five feet in eighteen and a half miles, giving a gradient of forty-eight and four-tenths feet per mile, in fifty per cent rock. The plateau of Willailootzas, one mile long, will be entered by a curve, with a radius of about two thousand feet, and the road pass along the north bank of the lake, with side locations in eighty per cent trap rock, easily worked. This lake should be partially drained; its shores are steep and of broken stone.

There will be some little difficulty in preparing a proper depot for the workmen, tools, &c., at the entrance of the tunnel, or, if the long tunnel be used, then, commencing at the point eighteen and a half miles east of Willailootzas, there will be eighteen and a half miles with a gradient of fifteen and two-tenths feet per mile, and with but little side cutting, through a thickly timbered country as far as Kitchelus.

Both tunnels will pass through solid rock (silicious conglomerate) and there will be cutting through rock of similar character on the mountain spur bordering the valley of the Nooknoo. Yellow pine grows abundantly on the Yakima, ninety-six miles from its mouth, and can be rafted down at high water. Granite can be brought down from a point about one hundred and forty miles above the mouth of the Yakima, and good sandstone and limestone are to be found on Puget Sound.

Seattle is an admirable harbor for a great railroad depot, being land-locked, defensible, accessible, and commodious. The harbor at the entrance of the Snoqualmoo, or, as it is named in the lower part of its course, the Snohomish

(171) river, has mud flats, with a good harbor between the flats and Point Elliot to the south. The suggestion is, whether the line may not follow down the Snoqualmoo on its north bend, cross over to Whidby's island, and the depot be established on its western shore nearly opposite Point Townsend. This will require works of the largest and most expensive character, for an artificial harbor must be made by a breakwater midway between the island and the opposite shore. When it is recollected that with such a breakwater—for such a form and position can be given to it as that a heavy battery, with a keeper's tower, can be planted on it—the extensive waters of the sound can be defended by a single system of works at Port Townsend, the suggestion may not be altogether without significance. A small work would be, of course, required at Deception Passage.

BRANCH ROAD DOWN THE COLUMBIA TO VANCOUVER, AND EXTENSION VIA LINE OF COWLITZ RIVER TO PUGET SOUND.

This branch leaves the main trunk twenty miles before reaching the Columbia. There should, if practicable, be but one bridge crossing of the Columbia, for the two branches, supposing the branch down the Columbia should keep along its south bank, as minute surveys can determine the particular details. On the north side of the river the party of Mr. Tinkham, in 1853, with Stevens, found it necessary in only two instances to cross the rocky spurs which jut out from the river bluffs. The Columbia river pass is not only practicable, but is remarkably favorable. The only tunnel required will be to effect the passage around Cape Horn mountain. This will not exceed seven hundred feet in length, and a close examination may prove even this unnecessary. There need be no gradient to exceed ten feet per mile, but considerable side-cuttings in the rock will be necessary.

The high floods to which the river is subject are the most serious obstacles to obtaining the advantages of cheap construction offered by its valley. To avoid these it will be necessary to run the road at some distance above the water; but as much of the slope consists in debris, workable with the shovel, embankments will be easily made, and when constructed will be of the most durable kind. At eastern prices this work might be done at fifty cents per cubic yard.

The tunnel through Cape Horn mountain would cost, at eastern prices, say sixty-five dollars per lineal foot—a high estimate, considering the character of the road. The easy access to this part of the route will make it cheaper of construction than parts of the same character further in the interior.

The bluffs along the Columbia cease near Cape Horn, and passing through a level bottom land, partly wooded, as far as the Cowlitz, it turns northward from the Columbia, and follows the wide Cowlitz valley, with an easy ascent, to the prairies occupying about half of the country on the line from thence to Puget Sound. Along the eastern shore of Puget Sound, from Steilacoom to Seattle, it passes through dense forests for most of the way, and crosses several large streams, which will probably make a terminus higher up the sound desirable for a route approaching by way of the Columbia. Good building stone, excellent timber, and abundant water, is found on this part of the route, while fine gravel, constituting the soil through most of the way, offers a superior material for the road-bed. If we pursue the Hell's Gate route, via Mullan's Pass, a railroad line can be laid across the Rocky Mountains with only a mile tunnel through the divide, which is but one and a half measured mile from base to base, and that no excessive gradients will be required on the eastern approach. The descent down the valley of the Little Blackfoot and Hell's Gate is exceedingly favorable. Thus a line can be laid down from the Mississippi to Olympia, on Puget Sound, with but short and few tunnels, but which will be two hundred and seventy six miles longer than the route by Cadotte's, the Coeur d'Aléne and Snoqualmoo

(172) Passes to Seattle. We cross the Rocky Mountains by the Northern Little Blackfoot or Mullan's Pass, then follow down the Little Blackfoot and Hell's Gate valleys, cross over the Jocko divide to Hell's Gate, follow down Clark's Fork to below the Pend d'Oreille lake, cross over to the Spokane, and, finally, after passing over the great plains of the Columbia, follow down the Columbia valley to near the mouth of the Cowlitz and reach the sound by the easy and practicable line of the Cowlitz and intermediate country.

By this route the distance to Olympia from St. Paul will be two thousand and forty miles, against one thousand seven hundred and sixty-four miles, the distance to Seattle by the route of the tunnels.

The distance to Seattle by the no tunnel route will be 2,092 miles. By the tunnel route the elevation above the sea is as follows:

On the route from Breckinridge to Vancouver the distance and elevations are as follows:

The sum of ascents and descents from Breckinridge to Seattle is 21,787 feet, and to Vancouver 17,587. Equated distances from Breckinridge to Seattle, via Cadotte's Pass, 1,957.14; equated distances from Breckinridge to Vancouver, via Codotte's Pass, 1,859.69.

Before giving the estimate, I will state that there are many advantages in bringing the line to the Missouri rather than taking it from Milk river and crossing the Marias and Téton high up towards the mountains. The cost is diminished thereby; the road is brought at once directly, to the head of navigation of the Missouri; it dispenses with the necessity and expense of a spur road; it renders unnecessary the reservoir for water at Grizzly Bear lake; there will be the most ample supply of water along the line of the route about to be estimated upon; Box Elder, Sun river, Elk Fork, the Dearborn, the several tributaries of the Dearborn, and the creeks flowing westward from the divides of Cadotte and Lewis and Clark will, as well as the Missouri, furnish an inexhaustible supply of the purest water; it will bring the whole of this portion of the route into the close vicinity of a well-wooded region; it will effect a great saving in transportation; it will be near water-power; it will hasten by six months the completion of this portion of the road; the old location, from Sun river to the Dearborn will involve exceedingly heavy excavations and embankments.

ESTIMATE OF COST

The estimate of cost of road is not given for the distance east from Breckinridge, on the western boundary of Minnesota, to which point the Minnesota and Pacific Railroad Company have located a road under the recent grants of Con-

(173) gress. Their route crosses the Mississippi near the Falls of St. Anthony, does not deflect more than 27 miles at any point from an air-line, and saves 20 miles in distance over the surveyed routes. Moreover, with means at hand it can be built for less than the estimate of $25,000 per mile, viz: for about $21,000 or $22,000 per mile.

One estimate is given of the cost of the road from Breckinridge to Seattle and Vancouver, both by Cadotte's and Lewis and Clark's Passes—first, by passing the plateau generally, and second, by the Missouri Great Falls and Sun river, as explained in this paper.

Estimate of cost of road from Breckinridge to Seattle, via Fort Union,, Fort Benton, Cadotte's Pass, Coeur d'Aléne mission, north of the Coeur d'Aléne lake, and the Snoqualmoo Pass, using the long tunnel. Entire distance, 1,544.51 miles.

Estimate of cost of road from Breckinridge to Vancouver, via Fort Union, Fort Benton, Cadotte's Pass, Coeur d'Aléne mission, north of the Coeur d'Aléne lake and the Dalles. Entire distance, 1,526.60 miles.

(174) Estimate of cost of branch road from Vancouver to Seattle.

Recapitulation of cost of road from Breckenridge to Seattle, with a branch road to Vancouver, and a branch road from Vancouver to Seattle.

The following is an estimate of cost of road, leaving the route on Sun river, passing up that river to Elk Fork; thence, along that fork, to Lewis and Clark's Pass, and thence to its junction with the Big Blackfoot. The cost from Fort Benton to Hell's Gate, as per preceding estimate, is $15,858,390. Distance 198.25 miles.

The cost of this portion of the route, by Lewis and Clark's Pass, will be as follows:

By taking Lewis and Clark's Pass, as above, the distance is increased 24.875, and the cost increased $1.541,731. The route by the Missouri to the mouth of Sun river will increase the cost over the route by the plateau from Fort Benton to Sun river as follows:

(175) GENERAL RECAPITULATION

Breckenridge to Seattle

Breckenridge to Vancouver

ASTRONOMICAL DATA

In submitting the subjoined astronomical report, which has cost us much labor both in the field and office, I take much pride in stating that it comprises the first series of longitude observations ever made across the continent, north of the 42° of longitude. This section of our domain has never been the field where extended detailed surveys have been conducted. The first party, under Lewis and Clark, sent out by the government to map this region, failed to report any longitude observations, as is fully set forth in an extract from a letter of President Jefferson on the subject, which may be found in the seventh volume of his published works, page 224, and which is as follows:

"I had long deemed it incumbent on the authorities of our country to have the great western wilderness beyond the Mississippi explored, to make known its geography, its natural productions, its general character, and inhabitants. Two attempts, which I had myself made formerly, before the country was ours, the one from west to east, the other from east to west, had both proved abortive. When called to the administration of the general government I made this an object of early attention, and proposed it to Congress. They voted the sum of five thousand dollars for its execution, and I placed Captain Lewis at the head of the enterprise. No man within the range of my acquaintance united so many qualifications necessary for its successful direction; but he had not received such an astronomical education as might enable him to give us the geography of the country with the precision desired. The Missouri and Columbia, which were to constitute the tract of his journey, were rivers which varied little in their progressive latitudes, but changed their longitudes rapidly at every step. To qualify him. for making these observations, so important to the value of the enterprise, I encouraged him to apply himself to this particular object, and gave him letters to Dr. Patterson and Mr. Ellicott, requesting them to instruct him in the necessary process. Those for the longitude would, of course, be founded on the lunar distances. But, as these require essentially the aid of a timekeeper, it occurred to me that, during a journey of two, three, or four years, exposed to so many accidents as himself and the instrument would be, we might expect with certainty that it would become deranged, and in a desert country where it could not be repaired. I thought it then highly important that some means of observation should be furnished him, if any could be, which should be practi-

(176) cable and competent to ascertain his longitude in that event. The equatorial occurred to me as the most promising substitute. I observed only that Ramsden, in his explanation of its uses, and particularly that of finding the longitude at land, still required his observer to have the aid of a timekeeper. But this cannot be necessary, for the margin of the equatorial circle of this instrument being divided into time by hours, minutes, and seconds, supplies the main functions of the timekeeper, and, for measuring merely the interval of the observations, is such as not to be neglected. A portable pendulum, for counting, by an assistant, would fully answer that purpose. I suggested my fears to several of our best astronomical friends, and my wishes that other processes should be furnished him, if any could be, which might guard us ultimately from disappointment. Several other methods were proposed; but all requiring the use of a timekeeper. That of the equatorial being recommended by none, and other duties refusing me time for protracted consultations, I relinquished the idea for that occasion. But, if a sound one, it should not be abandoned. Those deserts are yet to be explored, and their geography given to the world and ourselves with a correctness worthy of the science of the age. The acquisition of the country before Captain Lewis's departure facilitated our enterprise, but his timekeeper failed early in his journey. His dependence then was on the compass and log line, with the correction of latitudes only; and the true longitudes of the different points of the Missouri, of the Stony Mountains, the Columbia, and Pacific, at its mouth, remain yet to be obtained by future enterprise."

No other party occupied this field till 1853, when Governor Stevens contemplated supplying this want so long felt for the correct geography of the country. Having been a member of his expedition, and familiar with the special difficulties under which this branch of big duties labored, I deem it germain to this portion of my report to here relate them: In the organization of his expedition, Captain Joseph Roberts, then of the 4th artillery, was detailed to accompany him across the country as chief astronomer; but within a few days of starting from St. Paul's Captain Roberts was relieved, when the duties devolved upon G. W. Stevens, (nephew to the governor,) James Doty, and two Hungarians. When one hundred and fifty miles west of St. Paul's these two Hungarians, for reasons satisfactory to the governor, were discharged, and young Stevens left almost alone, for Mr. Doty made no profession to astronomical ability. Young Stevens himself was not a practical astronomer, and the transit was not set up before reaching the mouth of the Yellowstone. At this point the observations were placed under the charge of Lieutenant A. J. Donaldson, late of the United States engineers, who, already occupied with labors that monopolized his time, gave only a general supervision to the subject. The consequence was that Stevens reached the Pacific coast without having collected any observation for a single longitude. In making his report to Congress the statement was made "that the astronomical observations being placed in charge of Lieutenant Donaldson, the latter failed to report any except for latitude." The sensative nature of Donaldson construing this to be a thrust at his ability to observe for longitude, protested, in an official letter to the Secretary of War, and which was published with Stevens's volume Pacific Railroad Reports.

Stevens regretted this loss very much, and tried to meet it by getting an especial appropriation to send his nephew over the line a second time; but in this he failed to get the necessary legislation.

Thus was this second opportunity allowed to pass without any fixed position on so long an east and west line being determined. Therefore, in taking the field, in 1858, the department authorized me to supply this information, which has been done, and the following tables will be found to be replete in all the material for these determinations.

The data have been collected with commendable zeal by Messrs. Weisner, Kolecki, and Culligan, and we had the good fortune of bringing back to Wash-

(177) ington our transits without any accident, and our five chronometers without one being allowed to run down. To those specially interested in this branch of science, the tabulated series will be of great value; and to those who would wish to review the originals, I would refer to the many field-books now deposited with the Topographical bureau, where all our original maps, tracing sketches, and field-books are deposited. One of the results of our labors show that both Fort Walla-Walla and Fort Benton have been thrown too far to the east—the former by 15′ and the latter by 4′ in arc.

WASHINGTON, D. C., February 1, 1863

DEAR SIR: I have the honor now to submit to you the records of the astronomical and meteorological observations made in connexion with the expedition to explore and open a military road from Fort Walla-Walla to Fort Benton the year 1859 to 1860. Volume A gives the comparisons of the chronometers and their relative rates for every day, assuming the rate of the sidereal to zero. The results of the errors for every day, whenever moon culminations had been observed, are given in a table of the appendix. Volume B contain pretty numerous series of sextant observations for time and latitude, generally on the sun's lower limb, some on Polaris and other stars, at twenty-eight static made by Mr. Theodore Kolecki, with three sextants, the time being recorded myself, using generally sol. chron. No. 7961 for observations on the sun, or sid.chron. No. 525 for observations on stars, if not otherwise stated. The record time observations is separated from that of the latitude observations at the beginning, but further on both are brought into one and the same convenient shape. The column headed "time at culm., and 2 meridian altitudes," or, shorter, "meridian, 2 alt.," shows sufficiently what can be reached through practice by a steady observer. The probable error of a result of a set of seven equal altitudes on sun is in many cases smaller than ± 0s.2. The double altitudes, reduced to meridian, give a probable error of ± 5", and even less, for a single observation. The index error has been observed frequently. The error of eccentricity, &c., of the sextant, has been determined from observations on objects north and south of the zenith, and checked by comparing. the measured with the computed distant of a Virginis to a Scorpii, at Fort Walla-Walla, June 20. In the reduction of the time observations Captain Lee's tables have been used for the computation of the equation of equal altitudes, and the correction for the equation of time was taken from the American ephemeris. In the reduction of the latitude observations the following corrections are used:

1st. Correction for reduction to meridian, correcting first the meridian distance in time for rate of chronometer, going with the corrected argument in Captain Lee's tables, and using the factor sec. a cos.l cos. δ.

2d. Correction for change in declination of the observed object, when the sun was observed.

3d. Correction for vernier of sextant No. 1, for 57 div. on the limb = 59 on the vernier.

From these corrected double meridian altitudes the mean has been used, and its probable error determined. To this mean added the mean index error, and the error for eccentricity, &c., of the sextant; further the sum halved, and from that the refraction, corrected for barometer and temperature., subtracted, gives the true meridian altitude of the observed object. To this the semi-diameter and the parallax in altitude added, when the sun's lower limb was observed, gives the true altitude of the object's centre at the earth's centre; and adding the declination of the object with the opposite sign, gives the true altitude of the equator at the place of observation, or, by adding the north polar distance of the object with the opposite sign—when the object is north of the zenith—the latitude of the place of observation. In that manner the latitudes of nineteen

(178) stations are computed, and the results incorporated in the table of geographical positions. Also some equal azimuth observations have been recorded with the original record of the sextant observations, but, as the sun stood too high, are, in consequence, of little value for the determination of the magnetic variation. However, the results for this element are given in the above table, as obtained from direct bearings of the compass to natural and artificial marks of the northern and southern horizon, the astronomical azimuth of these marks being well determined by the observations contained in volume C, the book of transits. About 4,000 transits, over the mean wire of the nine which were generally observed, are recorded.

1. Equatorial intervals.-The intervals of the wires to the mean wire for more than 100 objects have been frequently determined and compared. Combining the same interval from the same star from a large number of observations into one mean, and bringing the results of a large number of stars with the factor cosδ together into one mean, the following result for equatorial interval was obtained for lamp west and upper culmination

2. Collimation.-Polaris, λ Ursæ Minoris, and other circumpolar stars, have been frequently observed with lamp west and east on some or all of the wires. The observations gave an average res ult that all upper transits taken with lamp west are to be corrected by - 5s.50 sec δ. At Walla-Walla the collimation was only determined at the beginning and the end in that way, the transit-stand being too high, and being afraid of disturbing the instrument; but the collimation for the intermediate observations could be very well determined from the observations themselves, as stars for that purpose were observed.

3. Inclination.-The level was frequently read with care, giving sufficient time to rest. Also stars observed in general for its direct determination to avoid the inequality of the pivots. Observations on zenith and circumpolar stars were made for the value of one division of the level scale, with the result: 1 division = 1".00, and correction for inclination = 0s.0l7 b. sec. δ. cos. z, where b = [w - eX] + [w X - e] or four times the inclination of the axis expressed in divisions of the level scale; b is tabulated in the record under the column "level." The mean is recorded when observations were made before, during, and after the transit of the object. For some objects the transits and level are given separately, to check the above results.

4. Deviation.-No opportunity was omitted to observe close together high and low stars for the determination of the azimuth. Also, some natural and artificial marks of the northern and southern horizon have been made use of to obtain the change in azimuth during the time of observation, by measuring it with the micrometer and the movable wire, the value of one division of the micrometer being determined to be = 0s.04605.±0s.00005.

The correction for deviation = a sec. δ sin. z, a being the deviation, or its change, just as needed.

In reducing the transits, a more expansive table than given by Captain Lee for the three transit factors,

sec δ

sec δ cos z

sec δ sin z

has been used.

The observations recorded in volume four contain the following:

1. Observations for time, to determine the error of the chronometers and their absolute rate.

2. Moon culminations and moon culminating stars.-Great pains have been taken to get as many observations as could be got with the least handling or disturbance of the instrument for almost an hour before and after each transit of the moon's I or II limb. Observations for instrumental errors were made generally before and after that. In reducing these observations to obtain the absolute

(179) longitude of the places of observations, the American ephemeris, Bessel's formula for interpolation, corresponding observations from Greenwich, Washington, Harvard College, and Cincinnati, have been made use of; further, Lieutenant J.M. Schofield's table of corrections to the AR. of the moon's I or II limb, and to the moon culminating stars of the American ephemeris, improved the results considerably. The final result of the longitude of each station is given in the table of geographical position.

3. Observations on the sun and solar spots.—The latter were first recognized at the Coeur d'Aléne mission by James Culligan, my assistant. I took the pleasure to chase one for about a week with the formula Δ AR. = a + b sin. (β + γt). Where Δ AR. the difference in R. A. between limb and spot given by observation from day to day, γ the daily angular motion of the spot in its parallel at the sun. I computed for γ = 12°, 13°, 14°, the remaining constants a, b, β, and also the remaining errors of the observations. Representing in a diagram the sum of these errors as ordinates for the abcissa γ, it indicated a minimum sum of errors for γ =13º.15. Adopting this as the true γ, and the earth at rest made the sun revolve within 27.4 days, and correcting this result for the earth's motion, 25.3 days was obtained for the time of rotation of the sun.

4. Planets.-All the planets, except the asteroids, have been observed. This speaks for the excellent quality of the telescope made by Throughton & Simms, as well as for the beautiful, clear blue sky over the Rocky Mountains. Even the asteroids would have been hunted up if the American ephemeris of 1859 and 1860 would have given the elements for finding them. None of them were discovered anew, neither the planet between Mercury and the sun.

5. Satellites.-The four of Jupiter have been observed frequently, and also one of Saturn; but no occultation could be observed without bringing the instrument out of its position.

6. Occultations of stars with the moon had not been observed, for the same reason. Saturn and Venus came very near the moon, the first at Walla-Walla, the second at Hell Gate, and would have been observed. At Hell Gate, April 24, Venus was visible to the naked eye all day, even at noon.

7. Eclipses.-Two of them were observed. One of the moon, at the Bitter Root, February 6, 1860, and one of the sun, on board the steamer Key West, passing Fort Lookout, on the Missouri, on July 18. By the last eclipse a great error was committed by myself. I was ordered by you, at Fort Benton, to go back to the divide of the Rocky Mountains, but before I went, got discharged by an order of the Secretary of War, Mr. Floyd. I followed the demon, when speaking to me, "follow the law of gravity." I went down the river, not knowing that gravity lifts the spirits upwards, as every child knows that reads the Bible. But you have forgiven me, as I was misled by -

8. The comet, first seen by J. Culligan with the naked eye, near the northwestern horizon, at Fort Benton, June 21, 9.50 p. m. As this stranger could not be observed in the meridian, the instrument was moved in azimuth, and transits taken in the direction north-northwest to south-southeast. Only a few observations were obtained. The light of the comet became very faint, in consequence of the twilight and moonlight, and disappeared in the aurora borealis, on July 30.

9. Prime verticals, or observations with the transit.-The telescope here is moved in a plane nearly vertical, through east and west. These observations are very well adapted for the determination of the latitude of a place, as nothing but a chronometer and a vertical plane through east and west are required. The equatorial intervals of the wires in the transit being known, further the collimation of the mean wire ascertained from transit observations, the reduction of the prime vertical observations from one side wire to the transit over the line of collimation was performed by the following formula:

(180)

F being the equatorial interval in second of time, - 58.50 the mean collimation M = sin (L+D) sin (L-D .)

L being the latitude of the place of observation, and D the declination of the observed object.

A table has been constructed for lamp south, and another for lamp north, which gives at once for the argument log. M the reduction of one side wire to the transit over the line of collimation for each of the nine wires.

To reduce them further to latitude, the hour angle p, and the declination of the observed object was looked for in the American ephemeris, and then the latitude of the place of observation obtained by the formulæ: log. tang. L = log. tang. D-log. cos. p, supposing the instrument free of errors. The indications of the level have been simply converted into arc by the value of 1 div = 1."100 and added.

For corrections to the assumed chronometer error and rate, the mean collimation and deviation have been determined from the observations themselves, by the use of differential coefficients to these small unknown quantities. The equations, which the observations furnish in great abundance, solved by the method of least squares, or some approximation to it, and then, with them, the above results for latitude corrected.

An investigation on the weight of the single results has been made and found to be directly proportional to sin2D, and inversely proportional to 1+sin2p. Accordingly the following weights to the results of the principal stars of the Bitter Root latitude.

METEOROLOGICAL DATA.

 Vol. D. Meteorological observations.-These were made with Green's cistern barometer, No. 1273, aneroid No. 18314, dry and wet bulb, black and naked bulb, maximum, and a number of small pocket thermometers.

1. The barometric observations were made in order to use them for the determination of the absolute height of the principal stations. The accuracy of the resulting heights depends more on the season and the duration of the series than on a great number of observations made during a short time. I computed the probable error from a series of daily observations, three in number, during 29 years, made by Professor A. Caswell, at Providence, Rhode Island, to be, respectively.

(181)

Accordingly, a series of seven September months would have the same weight as a series of five years observations when worked with the mean without regard to weights. Further, the series at the Bitter Root during November, December, January, February and March, has the weight 14, and that at the Coeur d'Aléne mission during the short time of August and half of September the weight 10, taking the weight corresponding to the probable error of 100 feet as unit.

The results of the absolute heights become considerably improved by correcting the mean barometric pressure of the air for its periodic and non-periodic variations as collected by the Smithsonian Institution in A. Guyot's meteorological and physical tables.

2. The observations with the aneroid were made for the determination of the differences of heights between the intermediate points and the principal stations. Another Green's cistern barometer, No. 1275, was left at Walla-Walla in care of Thomas A. McParlin, assistant surgeon United States army, to make corresponding observations for this purpose. A series of daily observations, three in number, during one year, has been thankfully received.

As the distance from Walla-Walla increased, barometer 1273 was left stationary during the time the aneroid was travelling on foot or on horseback. In that way a profile was obtained of the road from Coeur d'Aléne mission to the Bitter Root, and checked by actual levelling by Mr. W. W. Johnson. The differences gave a probable error of five feet to points determined by the aneroid, the determination by actual levelling being correct.

The results of the heights of the principal stations, and of some intermediate points, are annexed to the table of geographical positions.

3. The observations for temperature contain:

a, the temperature of the mercury in the barometer in the column headed " attached."

b, the temperature of the air in the shade in the column headed "det,"[wet] or "dry."

c, the dry and wet bulb observations for the hygrometric condition of the air.

d, black and naked bulb observations for the relative heating power of the sun.

e, the temperature observations of the soil at the surface, and of the air half an inch, one foot, and four feet above the ground, exposed to the action of the sun, for the interesting study of the radiant heat from the surface of the earth.

f, the temperatures of the water in rivers and creeks for the determination of their exceedingly simple laws, as herewith almost the hour of the day and the distance between two points could be determined. A single observation of the temperature of the water in a spring at any time gives the yearly mean temperature of the air in shade generally just as accurate as a series of observations made direct in the air during a number of years. No spring has been passed, therefore, without taking a drink and a temperature. The number of springs increased towards the foot of the mountains, and are found at all heights, even at 6,000 feet above the level of the sea.

(182) The mean temperature of the air in the shade between the Cascades and the Rocky Mountains, for the 47th parallel, reduced by the Smithsonian coefficient of 300 feet for 1°, increase in temperature in going down to the level of the sea, may be set at 55º F.; that is, 2° more than at Washington, D. C., latitude 39º.

By comparing the observations for temperatures of the same time at stations of different heights, the above coefficient was found to be the same for night observations, but, for the day, 200 feet would come nearer the truth. By ascending 4,000 feet above the Coeur d'Aléne mission, during moonlight on the night of September 10 to 11, the temperature of the air stood actually over 10° higher than in the valley for this special case.

4. The amount of rain and snow that actually fell.-The yearly amount of rain within the above geographical limits may be set down at 20 inches of water, or to one-half that falls in the District of Columbia upon the same area, or to 50 per cent more than falls upon the most fertile portions of Germany.

In winter it is snowing frequently by quarter inches as a whole day's labor, to be destroyed the following day by a warm sun. If any snow should remain, the temperature of the air near zero, or even sometimes 40º below zero, the freezing point of mercury, the result of an excessive clear and calm night will freeze the snow to an ice crust for the deer to walk on without snow-shoes, and, on the morrow, to enjoy the bright sun with a temperature of 70° and more.

The line of eternal snow must be over 8,000 feet above the level of the sea, as the yearly mean temperature of the air in shade can be expected only at heights 7,200 feet above the ocean. The following table will represent the depth of snow in inches lying on the ground on the bank of the Bitter Root during the winter of 1859 and 1860, at different dates:

Towards Sohon's Pass the maximum depth of snow increased in two ratios: For the distance of each mile from the Bitter Root towards the divide, 1/2 an inch; and, for each 100 feet above, 1 3/4 inch has to be added.

Along the valley of the Bitter Root the maximum depth of snow is almost independent of the distance, and the coefficient for height considerably smaller. Within heavy timber, the ground and snow remains unfrozen; the snow may accumulate at high points to the depth of 7 feet, even 10 feet. But, by avoiding the heavy timber, the snow will offer no great obstruction to travel with horses or locomotives from the Missouri to the Columbia.

5. The observations with the water-gauge, besides the average breadth, depth, fall, and velocity of the water in rivers and creeks, form important hydrographic informations for agriculture, navigation, and industrial purposes.

6. Wind and clouds.-The force of the wind is reduced considerably by the broken surface of the ground on the western side of the Rocky Mountains. Therefore., calms are frequent, and camp life very pleasant, especially in the woods, even during the winter. The excessive cold of a few hours is checked by an overclouded sky of long duration, and the excessive heat, during the days of summer, by a gentle, cool, and healthy mountain breeze. At Walla-Walla a temperature of 108° in the shade has the same effect on a healthy body with wet skin as a temperature of 9U° at Washington. The direction of the wind is very variable. The smoke of the camp fires is moving around the horizon within a few minutes direct and reverse to Dove's law; the direct motion, following the sun, being the preponderate, especially for the upper wind. That, during the day, the warm air moves up and the cool air down has been observed frequently at Walla-Walla. Apparently, by a calm air, a cylinder of dust about

(183) 200 feet in height was formed by these two currents of the air, and lasted a few seconds. But generally the heated air of the valley climbs up the sides of the mountains, heating their slopes additionally, less during the day, more during the night, and is ascending at the top still further on to fill the places of the cool air that falls down in the morning perpendicularly into the valley. Therefore, during the night and morning, the mountains are surrounded by heated air, and the cool air fills the valleys and covers the plains in order to become heated the following day to begin the same round again. Supposing now the radiation to space during a clear and calm night to be about the same for different heights, it must freeze, therefore, first in the valley that is filled with the cooler air.

For this circular motion of the air in mountains the early farmer has to settle on their slopes

At a mean height, and the settler of the valley must protect himself from the late frosts of May and June. Further, this uprising current is the cause of so many beautiful clear days and nights, especially during the summer months, and the cause of the dry spell.

Towards the end of the dry season, the middle of August, the heavy wooded Coeur d'Aléne Mountains begin to smoke—the forests are burning. It is believed that they are set on fire by the lightnings, or by the Indians, more likely.

Whilst I ,was drawing a profile of the road, and by attempting to represent all known heights of the mountains, of settlements and camps along the rivers, in valleys and prairies of Governor (the late lamented General) I. I. Stevens's Northern Pacific Railroad district, between the longitude of the mouth of the Columbia, on the west and Fort Union on the east, and within the parallels of 45° and the northern boundary, your signature was found most wonderfully written by the pen of nature: From the Pacific along the Columbia up to Mount Adams, down to the Cascades, up to Mount Hood and down to the Dalles, the profile is an M; along the Columbia, the Walla-Walla, the Touchet to the head of Reed creek, down to the Tukoñon to where Lewis discovered the Snake river, up the Pelouse on to the high plains of the Columbia and down to the St. Joseph, the profile is a U; up the Coeur d'Aléne to Sohon's Pass, and down the St. Regis Borgia to the Bitter Root, the profile is an L; up the Bitter Root, Hell Gate, Little Black foot to Mullan's Pass, and down the Little Prickley Pair, the profile is also an L; by the Medicine Rock, Dearborn, Sun river, over the plains to the right of the Teton, to Fort Benton and along the winding Missouri to Fort Union, the profile is an AN.

I remain, sir, very respectfully, yours,

J. WIESSNER, Astronomer.

 

Captain JOHN MULLAN, U. S. A.

Commanding Military Road Expedition.