68 
MR. AIRY ON THE OBSERVED DEVIATIONS OF THE COMPASS 
No 
1 9- 
1 
10, 
! 
12. 
Ship’s name 
Jackal. 
1 Trident. 
Place of observation 
Plymouth. 
Tagus. 
Pireeus. 
Greenhithe. 
Time of observation 
1845. 
1847. 
1846. 
1846. 
Index correction 
— 0° 12' 
+ 0° 4' 
-0° 4' 
— 0° 37' 
Approximate modulus 
•297 
•216 
•182 
1 -366 
Approx, starboard angle ... 
31‘’-40 
31'’-10 
31-'’58 
1 0‘’-32 
Observed 
deviation 
uncor- 
rected. 
Residual 
error. 
Observed 
deviation 
uncor- 
rected. 
Residual 
error. 
Observed 
deviation 
uncor- 
rected. 
Residual 
error. 
Ot)served 
deviation 
uncor- 
rected. 
Residual 
error. 
Apparent azimuth of ship’s head. 
P 
r 0 
] 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
O t 
— 2 15 
-b 2 40 
+ 8 58 
+ 13 7 
+ 13 18 
+ 17 15 
+ 18 7 
+ 17 47 
+ 15 35 
+ 14 38 
+ 13 22 
+ 11 40 
+ 9 55 
+ 85 
+ 5 35 
+ 4 12 
+ 2 20 
— 0 12 
— 2 32 
— 4 55 
— 6 30 
— 8 45 
— 10 52 
— 13 30 
— 15 45 
— 17 25 
— 18 25 
— 18 25 
— 17 15 
— 15 45 
— 11 55 
— 7 25 
(-0 27) 
+ 1 8 
+ 4 8 
+ 5 9 
+ 4 29 
+ 3 59 
+ 2 33 
+ 1 9 
(-1 54) 
-2 49 
— 3 28 
— 3 54 
— 3 48 
— 3 15 
-2 59 
-1 16 
( + 0 8) 
-1-0 56 
+ 1 34 
+ 2 39 
+ 3 55 
+ 4 7 
+ 3 58 
+ 2 24 
( + 1 14) 
— 0 22 
-1 59 
— 3 15 
— 3 56 
-4 49 
— 3 45 
— 2 21 
o / 
— 1 0 
+ 30 
+ 6 40 
+ 9 20 
+ 11 20 
+ 12 20 
+ 12 0 
+ 12 0 
+ 11 40 
+ 10 20 
+ 9 20 
+ 90 
+ 5 40 
+ 4 40 
+ 3 20 
+ 2 40 
+ 20 
+ 1 20 
— 1 0 
- 1 0 
— 3 40 
— 4 0 
— 7 40 
-10 0 
— 12 40 
— 13 20 
-15 20 
-15 0 
— 14 40 
— 14 40 
— 9 20 
— 5 40 
(+1 14) 
+ 2 49 
+ 4 5 
+ 4 27 
+ 4 19 
+ 3 27 
+ 1 36 
+ 0 30 
(-0 31) 
— 2 3 
— 2 45 
— 2 20 
— 4 27 
-3 49 
— 3 17 
— 1 46 
(-0 6) 
+ 1 39 
+ 1 43 
+ 4 1 
+ 3 29 
+ 3 1 
+ 2 52 
+ 1 38 
(-0 21) 
-0 49 
-3 7 
— 3 32 
— 4 25 
— 6 3 
— 2 35 
-1 6 
— 6 40 
+ 30 
+ 6 30 
+ 8 20 
-blO 40 
+ 11 20 
+ 12 20 
+ 10 30 
+ 10 0 
+ 90 
+ 80 
+ 6 15 
-1-4 0 
-b 3 15 
+ 30 
+ 1 20 
-b 0 40 
— 1 0 
— 1 20 
— 2 40 
— 2 40 
— 4 40 
— 5 40 
— 8 20 
- 9 40 
— 11 20 
— 12 0 
— 12 40 
— 11 5 
- 9 40 
- 8 0 
— 4 30 
(+0 9) 
-bl 44 
+ 3 14 
+ 3 11 
+ 3 50 
+ 3 4 
+ 2 56 
+ 0 20 
( — 0 33) 
— 1 30 
-2 5 
-2 59 
-4 4 
— 3 20 
— 1 51 
-1 37 
(-0 17) 
+ 0 8 
+ 1 48 
-b2 21 
-b4 2 
-b3 28 
4-3 36 
-bl 42 
( + 0 45) 
— 0 58 
-2 3 
— 3 34 
-3 9 
— 3 13 
— 3 17 
— 1 41 
+ 3 12 
+ 8 25 
+ 13 44 
+ 18 37 
4-21 7 
+ 21 45 
+ 22 15 
+ 22 26 
+ 20 18 
+ 18 50 
+ 16 30 
+ 13 0 
+ 11 0 
+ 7 30 
+ 60 
+ 2 20 
- 0 6 
— 2 45 
— 5 58 
— 8 42 
— 10 55 
— 13 25 
— 17 10 
-19 17 
-20 35 
— 21 22 
— 21 12 
-19 40 
— 18 15 
— 14 40 
— 9 38 
— 3 50 
( + i 17) 
+ 2 26 
+ 3 52 
+ 5 10 
+ 4 35 
+ 2 41 
+ 1 22 
+ 0 32 
(-1 46) 
-2 31 
—3 19 
-4 32 
-3 38 
— 3 43 
— 1 26 
-1 5 
( + 0 35) 
+ 2 0 
+ 2 40 
+ 3 31 
+ 4 23 
+ 4 25 
+ 2 29 
+ 1 23 
(+0 15) 
— 1 15 
-2 37 
— 3 22 
— 4 51 
— 4 41 
-3 26 
-1 39 
r 
Quadrantal coefficients 
o / 
+ 4 35 
— 4 18 
+ 3 59 
— 4 5 
+ 4 15 
— 4 5 
+ 4 5 
-4 19 
+ 3 40 
-3 29 
+ 3 25 
-3 35 
O / 
+ 4 8 
— 4 3 
+ 4 10 
-4 22 
Mean quadrantal coefficient 
+ 4 14 
+ 4 11 
+ 3 32 
+ 4 11 
True modulus 
•305 
•220 
•186 
•375 
True starboard angle 
31‘’-46 
31‘’-19 
3P-61 
0-P29 
