APPENDIX A 
ASTRONOMICAL OBSERVATIONS WITH SEXTANT. 
I. Observations on the route of the main party from Benicia to the point where the command 
separated, near the Three Sisters, Oregon Territory. 
CAMP 7—JULY 15, 1855. 
Observer — Lieut. R. S. Williamson, U. S. Top. En 
gineers. 
CAMP 11—JULY 19, 1855—Continued. 
Observer — Lieut. R. S. Williamson, U. S. Top. Engineers. 
Object observed. 
Time of observ’n 
by chronometer. 
Observed double 
altitudes. 
Object observed. 
Time of observ’n 
by chronometer. 
Observed double 
altitudes. 
li. m. 
s . 
d . 
m. 
s. 
h . 
111. 
s. 
d . 
m. 
s. 
. , . 
9 31 
33.5 
88 
46 
30 
Polaris. 
9 
22 
03.5 
79 
00 
50 
9 33 
48.0 
89 
22 
00 
9 
24 
36.5 
79 
01 
10 
9 34 
50.0 
89 
42 
30 
9 
27 
52.0 
79 
05 
30 
9 3G 
09.0 
90 
08 
00 
9 
29 
08.0 
79 
04 
50 
9 37 
26.5 
90 
34 
20 
9 
30 
38.0 
79 
06 
10 
9 38 
46.0 
91 
00 
30 
9 
32 
23.5 
79 
08 
20 
9 39 
56.5 
91 
23 
20 
9 
33 
24.5 
79 
08 
50 
9 
34 
50.5 
79 
09 
20 
9 1G 
07.0 
100 
47 
50 
9 
36 
56.5 
79 
09 
40 
9 18 
20.0 
100 
02 
10 
9 
38 
33.0 
79 
12 
10 
9 20 
13.5 
99 
17 
00 
9 21 
27.5 
98 
51 
20 
9 22 
52.0 
98 
18 
10 
Index error —2' 15". 
Barometer 29.7 in. Thermometer 
9 24 
17.0 
97 
46 
10 
780. 
9 25 
28.0 
97 
20 
30 
Polaris. 
9 00 
32.5 
77 
46 
20 
9 02 
40.5 
77 
46 
30 
9 04 
43.0 
77 
46 
50 
FORT READING- 
-JULY 22, 
1855. 
9 07 
05.5 
77 
48 
10 
9 08 
27.5 
77 
49 
20 
Observer — Lieut. R. S. Williamson 
, U. S. 
Top. Engineers. 
9 10 
07.5 
77 
50 
20 
9 12 
15.0 
77 
52 
10 
h . 
m. 
s . 
d . 
m. 
5. 
a Cygni. 
9 
46 
14.0 
118 
32 
50 
Index error 
—lO 0G' 35". Barometer 29.8 in. 
Ther- 
9 
47 
55.5 
119 
09 
20 
mometer 09°. 
• 
9 
49 
48.5 
119 
48 
30 
9 
51 
05.5 
120 
15 
50 
9 
52 
32.5 
120 
46 
50 
CAMP 11—JULY 
19, 1855. 
9 
54 
17.5 
121 
23 
50 
Observer — Lieut. R. S. Williamson, U. S 
Top. Engineers. 
Arcturus .. 
9 
57 
55.0 
73 
58 
40 
10 
00 
11.5 
73 
05 
40 
10 
02 
37.0 
72 
1 l 
30 
h . in. 
s . 
d . 
m. 
S. 
10 
04 
28.5 
71 
28 
20 
8 57 
23.5 
97 
10 
30 
10 
06 
11.0 
70 
49 
50 
8 59 
47.0 
98 
01 
10 
10 
07 
55.5 
70 
10 
00 
9 01 
41.0 
98 
41 
00 
9 02 
59.0 
99 
08 
20 
Polaris . 
9 
21 
35.0 
79 
44 
20 
9 04 
14.5 
99 
34 
50 
9 
23 
00.0 
79 
44 
40 
9 05 
25.5 
100 
00 
00 
9 
26 
38.5 
79 
47 
50 
9 
29 
06.0 
79 
49 
30 
Arcturus. ... 
9 08 
52.0 
96 
49 
10 
9 
3 J 
27.0 
51 
10 
9 10 
41.0 
96 
09 
30 
9 
32 
59.5 
79 
53 
00 
9 12 
04.0 
95 
37 
10 
1 
9 13 
30.0 
95 
06 
00 
9 14 
43.0 
94 
39 
30 
Index error — 2' 15' 
. Barometer, 29.6 in. 
T ner- 
I 9 1G 
18.0 
94 
03 
20 
mometer, 850. 
