,1! 
K 
42 SURVEY OP IDAHO-MONTANA BOUNDARY LINE. [bvll.1 
way vertical angles were checked by reading backsights and for 
sights; and thus levels were carried over the whole line. The heig. 
of the instrument above the ground station was determined at ea( 
point, and a corresponding height was sighted on the stadia rods. Th 
height was obtained by having one of the legs of the tripod mark^ 
to tenths of a foot and by using the plumb bob as a measuring line. 
The magnetic declination was read at each transit station. 
The stadia line was divided into four sections : 
First section. This section extended from the zero of the rando] 
line, namely, the summit of the Bitterroot Mountains, to transit st* 
tion 154, and was controlled by connection with the triangulatio E 
system at both terminal points. At the summit of the Bitterroc | 
Mountains it was connected by traverse with the triangulation sts 
tion Divide, and transit station 154 was located directly by triangr, 
lation. The distance determined by stadia was 62,071 feet and b 
triangulation 62,276 feet, the discrepancy being 205 feet, or 1 in 304 
The azimuth correction in this section was found to be 0° 0' 33" coil 
responding to a swing of 10 feet to the east in the random line a i 
station 154 m order to make it a true meridian line. 
Second section. This section was included between stations 154 am 
800. Station 800 was connected by a short traverse with the trian-u 
lation station Buckhorn. The distances determined by stadia am 
triangulation were, respectively, 228,014 and 228,734 feet the dif 
ference being 720 feet, or 1 in 318. The azimuth swing at statioi , 
6° 01^04' t0 thG eaSt ' C0rreSp01ldin S t0 an an S u1 ^ correction oi \t 
Third section. This section was between stations 800 and 949 Sta- 
tion 949 was located directly by triangulation. The distance by stadia 
was 49, 132 feet and by triangulation 49, 190 feet, the difference being 58 , 
feet, or 1 m 848. The swing in azimuth at station 949 amounted to 12 £ 
feet to the east, corresponding to an angular correction of 0° 0' 52" 4 
The positions of transit stations 0, 154, 800, 949, and 1046 corre- r< 
spond approximately to those of monuments 92, 78 23 8 and 
respectively. ' ' ' ) 
Fourth section. This section closed on the international boundary 
and lt W as unfortunate that a location by triangulation could not be 
obtained near its terminus, but the nature of the country rendered 
such a location impracticable, there being no elevated points near by 
and the timber being very tall and dense. It was therefore checked 
by careful steel-tape measurements, the tape being held horizontally 
under a constant tension of about 15 pounds, a plumb bob being used 
at each end. This section extended between station 949 and a point 
45 feet north of station 1046. The distance by stadia was 33,103 feet 
and by steel-tape measurement 33,219 feet, the discrepancy being 116 
feet, or 1 in 286. & 
It is proper to add that there are two small corrections which should 
