24 
SURVEY OF IDAHO-MONTANA BOUNDARY LINE. 
[BULl 
The figures relating to this description, which were kindly furnis 
by the Superintendent of the United States Coast and Geodetic Sun 
are presented below: 
Resulting difference of longitude between the astronomic stations at Spoh 
Washington, and Helena, Montana, as determined by the United States C 
and Geodetic Survey in September, 1888. 
1 
Date. 
Observer. 
Prom western 
or Spokane 
signals. 
q 03 
u a 
03 w 
Xr-, 
tHa 
gxg 
W 
£ 
w 6C 
° 03 . 
o3 C o3 
03 03 a 
O 03 
oog 
'-£ uo'rt 
o »© 
O 
O 
03 
03 TJ 
03 O 
5 
a 
o 
o 
O 
8 
a 
03 
03 
5 
6 
a 
o3 
M 
o 
ft 
02 
a 
w 
1888. 
Sept. 13.... 
Sept. 15..., 
Sept. 33.... 
Sept. 34.... 
Sept. 36.... 
Sept. 37.... 
Sept. 38.... 
Sept. 39...- 
< 
■ a 
'& 
W 
d 
a . 
m 
o 
o3 
S 1 
< I 
P3 ( 
31 34. 193 
.318 
.399 
.383 
31 34.616 
.703 
.667 
.663 
21 34. 171 
.164 
.347 
.334 
Mean... 
31 34.591 
.673 
.635 
.619 
Mean . . . 
0.023 
. 054 
.053 
.059 
21 34.183 
.191 
.373 
.354 
+0. 208 
—0.208 
21 34.390 
.399 
.481 
.462 
.396 
.479 
.438 
.433 
6 
5 
5 
10 
4 
4 
5 
5 
+0. 047 
+ .038 
- -044 
- .025 
+ .041 
- .042 
- .001 
+ .004 
± 009 
.047 
31 34.325 
0.025 
.029 
.042 
.044 
21 34. 604 
.687 
.646 
.641 
.035 
21 34.644... 
21 34.435 
- 
Weighted mean. 
21 34.437 
Transmission time, 0s.020 ± 0s.002. 
Personal equation, Marr-Sinclair, Os.308 ± 0* 009 
At Spokane transit No. 19 was mounted in the grounds of the county court-house 
of ftT t'TZ* f °- 18 ™ m ° Unted ° Ver the Station in the northwest corner of the groun 
A A Spokane-Helena =31" 34^.437 ± 0*.009. 
A Helena (transit 1888), 7b 38 m 08s. 789 ± Qs.053. 
A Spokane (transit), 7h 49™ 43».336 ± 0«.053. 
117° 35' 48".39 ± 0".80. 
From the foregoing it will be observed that the probable error o 
the longitude determination of the Spokane pier is 0".80, or about 5 
teet Through a connection with the pier at Spokane the longitud 
of the meridian of the boundary line was established by triangulate 
and traverse, as will appear hereafter. 
It may be remarked, in connection with the foregoing, that whil, 
the meridian of the Observatory at Washington is, by law approve. 
September 28, 1850, the American meridian for all astronomical pur 
poses, the geodetic operations of the country generally are conducted 
with reference to the meridian of Greenwich as an initial point Gov- 
ernment maps are usually referred to Greenwich, and standard time 
is reckoned from it. 
