MAGNETIC OBSERVATIONS. 



215 



Hence 



After Binnacle Compass. 



o = — 1.1228 + 17.000 A x + 8.442 B x — 5.641 C, + 0.924 D x + 0.383 E x 

 o = — 0.8724 -\- 8.442 A x -j- 8.310 B x + 0.462 C,— 1.205 Z>, — 4.543 E x 

 o = — 0.0346 — 5-641 A x -\- 0.462 B x -\- 8.691 C, -|- 3-9°° -£ >l — 4-438 A 



o = — 0.0385 + A + i W— c . a ) 



= 4- 0.0018 -|-£ 1 +^C, + 0.0047 (E? — C, J ) 



^4, = -\- 0.0148 z=-f-o° 50'. 8 

 B x = + 0.0947 = 4-5 25.4 

 C x = — 0.0073 — — ° 2 5 -2 



A= + 0.0340 = 4- 1 57.1 

 E x = — 0.0012= — o 4.1 



Hence 



After Ritchie Compass. 



o = — 3.3336 4- 17.000 A, 4- 8.442 B, — 5.641 C, 4- 0.924 D x + 0.383 E x 

 o = — 1.9499 4- 8.442 A x 4- 8.310 B x 4- 0.462 C, — 1.205 Z>, — 4-543 A 

 = 4- 0.6086 — 5.641 A x 4- 0.462 B x 4- 8.691 C, 4- 3.900 D x — 4-438 A 

 o = — 0.0340 + D x + \ (B x * — C*) 

 = 4- 0.0008 + £ x + B x C x 



^, = 4-0.1684 = 4-9° 39' 

 B x = 4- 0.0659 = 4-3 46 

 C, = 4- 0.0203 = 4-i 9 

 A = 4- 0.0320 = 4- 1 50 

 E x = — 0.0021 = — o 7 



Hence 



After Azimuth Compass. 

 = 4- 0.4916 4- 17.000 A x 4- 8.442 B x — 5.641 C, 4- 0.924 Z>, 4- 0.383 A 

 = 4- 0.6880 4- 8.442 A x 4- 8.310 B x 4- 0.462 C, — 1.205 Z>, — 4-543 A 

 o = — 0.2024 — 5.641 A x 4- 0.462 A 4- 8.691 C x 4- 3.900 Z>, — 4.438 E x 



o = — 0.1116 4- 2>, 4-i (A J — c, 2 ) 



O = 4" 0.0002 4 A 4 A ^1 



^, '— — 0.0434 = — 2° 29'. 3 



i?, = — 0.0199 = — I 8.5 



C x = — 0.0552 = — 3 9-7 



Z>,= 4- 0.1129 = 4- 6 28.2 



E x = — 0.0013= — o 4.5 



Hence 



Forward Alidade Compass. 

 o _ _ L0908 4- 17.000 ^, 4- 8.442 B x — 5.641 C, 4- 0.924 D x 4- 0.383 .£, 

 0= _o.4iil 4- 8.442^4-8.310^4-0-462 C, — 1.205 A — 4-543 A 

 = 4- 0.4058 — 5.641 A x 4- 0.462 B x 4- 8.691 C, 4- 3.900 D x — 4-438 E x 

 o = - 0.0235 4- A + i W - c . 5 ) 



_ _ 0.0007 + E x + B x C x + 0.0125 (A 1 — Ci') 



A x = + 0.0615 = 4-3° 3i'-S 



.#, = — 0.0084 = — o 28.8 



C, = — 0.0166 = — o 57.2 



D x = 4- 0.0236 = 4- 1 "•« 



£ = 4- 0.0006 = 4-° l -9 



