208 
HINTS TO TKAVELtEM 
Finding the error of Compass by 0 ’s Azimuth. 
The observation for finding the sun’s true bearing and error of th§ 
compass is the same as that for finding apparent time, with the 
addition that the bearing of the sun’s centre, at the time of observation, 
must be taken with a prismatic or other compass. 
Example. 
July 25th, 1899, a.m. The following observations were taken with a 
sextant to find the error of the compass:—Watch 8 secs, slow of G-. M. T.; 
Index error — 2'; Ther. 80°; Bar. 29*7 inches. Bearings taken with 
prismatic compass. 
Latitude 
51 4 24 N. 
Times by Watch. 
h. m. s. 
9 38 40 
41 15 
4 ? 43 
Alt. 0 Ait. Hoiizon. 
Bearings of (£) * 
3 ) 123 3 8 
Mean.. .« .. ., .. = 9 41 12*7 
Error of Watch .4- o 8 
G. M. T., July 24th 
21 41 2o*7 
1*9 
39 
44 * 7 " 
+ 
1 
144 
19 
40 
59 *i 
90 
00 
00 
70 
19 
co * 9 
Mean .. .. 
Index Error 
Corr. Refraction 
Semi-diameter 
Parallax 
95 
22 
0 
94 
2 
0 
94 
42 
0 
1282 
6 
0 
94 
2 
0 
- 
2 
d 
) 94 
O 
d 
47 
O 
0 
~ 
50*5 
4 6 
59 
9-5 
4 - 
15 
46-4 
47 
14 
55‘9 
4 - 
5-7 
47 
15 
i-6 
i ?7 
55 
138 
39 
139 
22 
3)415 
56 
*Mean = 138 
38 
40 
180 
Cd 
Od 
S. 41 
21 
20 E. 
N.B. — When the 
True Azimuth is to 
the left of the mag- 
netic* the variation is 
West ; when True 
Azimuth is to the 
right, the va iation is 
East 
N 
I ' ’ 
True AU. .. .. 47 15 i e 6 Secant o- 16826? 
Lat.51 4 24 Secant o-201816 
N. P. D.70 19 00-9 
2)168 38 26-5 
i Sum.. «. = 84 19 13-2 Cosine 8*995491 
i Sum rv N.P.D, 14 00 12*3 Cosine 9-986898 
9-352468 =2 Log. Sin. Square *= S. 56 39 E. 0 ’s True Azimuth. 
" ■■ ■ ’ S. 41 21 E. O’s Magnetic Bearing. 
Error of Compass = 15 18 W. 
* When the bearing is taken with a prismatic compass, and is less than 90°, it is counted front N. 
towards E., as N. 70 0 E.; when it is greater than 90 0 and less than 180 0 , subtract the bearing from i8o c , and 
it is counted from S. towards E., thus, 160° would be S. 20 E°.; when it is greater than i8o u and less than 
270 0 , subtract 180 0 from the bearing, and it wdll be counted from S. towards W., thus, 2oo° is S. 2o° W. } 
wheu it is greater than 270°, subtract the bearing from 360®, and it is counted from N. to W., thus 340° is 
N. 20° W. 
