FINDING THE LOCUS OF GEOGRAPHICAL POSITION. 239 
66° 29' 25" with the observer's eye at a height of 31 feet 
above the sea-level and the index correction of the sextant 
— V 30". Chronometer time of observation, 6 h 28 m 34® ; 
chronometer slow on G. M. T., 4 h 2 m 18.2 s . Required the 
Sumner line of geographical position and the total error of 
the compass. 
Preparation of the Data. 
c. — 
6 h 28 m 
34“ 
Observed Alt. =66° 29' 25" 
c. c. = 
+ 4 
02 
18.2 
I. C. — 1 
30 
G. M. T. = 
10 
30 
52.2 
66 27 
55 
Estimated Long. = 
4 
00 
00 
W. Dip = 5 
29 
Estimated L. M. T. = 
6 
30 
52.2 
66 22 
26 
R. A. M. sun — 
0 
41 
30.0 
Ref. *= 0 
26 
7 
12 
22.2 
True Alt. =66° 22 / 
R. A. a Aurigse = 
5 
09 
28.2 
Hour-angle — 
2 
02 
54 = 
= 30° 43 / 30" 
From the Nautical Almanac, 
for Greenwich date of observation, April 2d, 10 h , 30 m , 52 8 .2 = April 2d .44 : 
R. A. M. sun =0 h 41 m 30 9 .03 
R. A. a Aurigse — 5 09 28.2 
Dec. a Aurigse = 45° 53' 56". 6 N. 
NOTE. 
Plotting the declination and hour-angle roughly with reference to the parallels 
and meridians (counted from the left-hand hounding meridian) of the Index to 
Plates, we find that the position of the observed body falls on plate 51 approxi¬ 
mately at the intersection of circumference 17.4 with radial 8400, and adding to 
8400 the co-latitude expressed, in minutes, which is 3044, we find the approximate 
place of the revolved position to be at the intersection of circumference 17.4 with 
radial 8400 + 3044 = 11444, which intersection falls within the limits of plate 
136. Turning now to plate 51 and plotting the hour-angle and the declination 
to the nearest minute, we find the position of the observed body to fall at the in¬ 
tersection of circumference 495.6 with radial 8410.1. Adding the co-latitude 
expressed in minutes to the number of this radial we obtain 8410.1 -j- 3044 = 
11454.1 as the number of the radial, at whose intersection with circumference 
495.6, on plate 136, the solution is to be found by reading off the altitude with 
reference to the parallels and the azimuth with reference to the meridians count¬ 
ing from the right-hand bounding meridian. 
