The formula for reduction of azimuth observations at any hour

The mean of twenty observations reduced in a similar manner = 147° 00' 51.15.

Check azimuths along the random line were measured with Young transit No. 6838. The instrument was usually set over one stadia station and a mark placed on another station. Six measurements (three direct and three reversed) of angle between Polaris and mark were then made. These observations were reduced at once by the

method and tables given in the Manual of Surveying Instructions issued by the General Land Office, 1894, pages 109-119. An example of record and computation follows.

[July 19, 1898. Stadia 77. D. L. Reaburn, observer.]

[July 19, 1898. Stadia 77. Latitude 48° 03'; longitude 116° 03'. Watch fast 42 368 on local time.]

Upper culmination Polaris, July 15...

Reduction to July 18

Upper culmination July 18, being culmination preceding time of ob

servation on July 19..

H. M. 17 43.5

-11.8

-17 31.7

[D. L. Reaburn, computer.]

Computa- Computa- Computa

Computa- Computa- Computa-
tion of tion of tion of
first ob- second ob- third ob-
servation. servation. servation., servation. servation. servation.

tion of fourth ob

tion of fifth ob

tion of sixth ob

Mean 179° 58′ 33′′ showing this portion of the random line to deviate from the true meridian by 1' 27".

TRIANGULATION.

The triangulation connecting the Spokane base with the boundary line was done with an 8-inch micrometer theodolite, reading by two micrometers to two seconds and by estimation to one second. Directions were read in sets, each set consisting of pointings with telescope direct and reversed from left to right and from right to left. Four or more of such sets were usually taken. A few secondary locations on or near the boundary line were made with the transit. All of the observations were reduced in the office by least squares.

The following list gives descriptions, latitude, longitude, azimuths, and distances of the triangulation stations determined which have a bearing on the boundary line.

A diagram of the triangulation is also presented. (See Pl. V.)

SPOKANE, EAST BASE.

Station mark: A dressed stone, 7 by 7 by 36 inches, set 30 inches in ground, 25 feet north of north rail, and 94 feet eastward from sign "U. S.

marked "Trent 1 mile." The stone is marked on top

+

E. Base."

[Latitude, 47° 41' 01.94. Longitude, 117° 16' 00".81.]

Station mark: A dressed stone, 7 by 7 by 36 inches, set 30 inches in the ground, 25 feet of north rail and 218 feet eastward from signboard, "U. S.

"R. R. X'ng mile." Top of the stone is marked

+
W. Base."

[Latitude, 47° 39′ 47.28. Longitude, 117° 22' 10".45.]

This point is connected, by direct measurement, with longitude pier of the United States Coast and Geodetic Survey of 1888 and with latitude pier of the United States Geological Survey of 1896. It is also connected, by triangulation, with the stations of the base expansion. The point located is the center of the flagstaff, which is over the center of the cupola of the new court-house.

Latitude, 47° 39' 51'.76. Longitude, 117° 25′ 49′′.21.

MORAN, SPOKANE COUNTY.

Location of station: On the northern end of a high, wooded ridge, about 8 miles southeast of Spokane, in a cleared field about 50 feet west of the ruins of a log cabin. A wagon road runs to the station.