ASTRONOMICAL OBSERVATIONS. 
545 
Finding the Latitude. 
(c) By Bole Star out of the meridian. 
This is a very convenient method of finding the Latitude, as the 
observation may be taken at any time when the star is visible; it is, 
however, a somewhat difficult star to take in the artificial horizon. 
The tables necessary for this form of computation can only be found 
in Nautical Almanack for each year. 
Example. —Feb. 18, 1877, at 9 h. 20 m. M.T. at place, in long. 
30° 10' 0" W.; the observed alt. of Polaris was 92° V 0"; index 
error,— 10." Find the Latitude. 
h. 
m. 
s. 
M.T., Feb. 18 . 
9 
20 
0 
Ditf. long. 30° 10' 0" in time (tab. 17, Raper). 
2 
0 
40 
days 
— 
— 
Gr.M.T.18 
11 
20 
40 
h. 
m. 
secs. 
Siderial Time at Greenwich Mean Noon (p. ii. NA.) 
21 
54 
12-45 
Acceleration for 11 h. 
1 
43-42 
n 20 m. 
3-29 
a 40 secs. 
0-11 
21 
56 
4-27 
M.T. at place. 
9 
20 
0 
31 
16 
4-27 
24 
00 
0 
Siderial time of observation . 
7 
16 
4-27 
O 
, 
// 
Observed altitude. 
92 
1 
0 
Index error . — 
10 
0 
*) 
91 
51 
0 
45 
55 
30 
Refraction. — 
56 
45 
54 
34 
Subtract... — 
1 
0 
Reduced altitude . 
45 
53 
34 
h. m. sec. 
With argument 7 16 4-27 (1st correction) . + 
1 
5 
Approximate Latitude... 
45 
54 
39 
h. m. 
With arguments 45° 54' and 7 16 (2nd corrn.) + 
57 
45 
55 
36 
h. m. 
WithargumentsFeb.l8 J 1877,and 7 16(3rdcorr.) + 
1 
2 
Latitude of the place . 
45 
56 
38 
II.— Finding the Longitude. 
(a) By finding Apparent Time at place by altitude of the sun, and thence 
the Longitude by chronometer. 
This is a most useful observation, but it must be borne in mind that 
it is only available when the observer is acquainted with the error of 
Pole star. 
Longitude, 
Sun-chrono¬ 
meter. 
