INSTRUMENTS FOR OBSERVING 
Taste 1.—Points of compass with corresponding azimuths to 
15 
nearest whole degree 
Compass 
Compass 
Compass 
Compass 
point Azimuth point Azimuth point Azimuth point Azimuth 
IN@rwa. 0 ashe 90 South_____ 180 West______ 270 
ING Aa ie ea hil). DBA Sea a ele OB She Wise 2 SIR AVG AC NTS oe 273 
NOL SUH ets Sa re @ |) 1, 16 Seas eee 96 | 8. % W____-_--- 186 | W. % N__----___ 276 
NGS on Om nmaa Sil nets zacuamat ais Br BSE OA Nea SSulAWe SA. NEM an O73 
INS oe Js 11 axG © See 101 Sipe hee age W. x N____ 281 
ING ox 1d, UA IB oe 145) (BSB 340 Hees 104 | S.x W. 4 W- 194 | WNW. 34 W____- 284 
ING oe Ja, PAs ees 17 || JSG, WA We eee 107 | S. x W. v3 Wi 197, |) WINWe 4 We = 287 
IN ds 1BL SA Wee = 20: | BSE. 44 E_______ 110 | S.x W. 34 W-. 200 | WNW. 4 W____- 290 
NINES 22 See 112 SSW. _ = 202 WNW____- 292 
INN Os |) Soy xe 1, CA IES IGS |) ISS WA Nive es 205 | NW. x W. 34 W__ 295 
NNE. % H-_--_= 28 | SE. x BE. % H____ 118 | SSW. Ws W___--_ 208 | NW. x W. rv; W__ 298 
NNE. 34 H_____-- 31 | SE. x E. 4% E____ 121 | SSW. 34 W_____- 211 | NW. x W. iY W__ 301 
NE. x N___- 34 SH. x H___ 124 SW. xS__. 214 NW. x W__ 304 
IND, SA ING ae es 87) Sa, SA I ea I SW SA is 22 217 | NW. 3% W__--__- 307 
IND, WG INS ee ee 8%) | Sd, US Wee ee 129 | SW. % 8_______- 219 | NW. 4% W______- 309 
INI, tH Nee AQ '\ Sia, WA oS ees ISP| SW. WA Soe e es sae 222 | NW. 14 W-_------ 312 
INH a eee 45 Sess 135 SWWeoesees 225 IN;Wise ee ee 315 
INDO, TZ oe 48 | SE. 4% S_____=2___ 188 | SW. 44 W______- 228 | NW. 4% N______- 318 
INDD, UA ee kee Bil ||) Sia, WA Seo 141 | SW. % W______- 231 | NW. 4% N____-_- 321 
NIB, OAD Lo eee Gi] Side OA Sal VS) || GN OA Wane e, OBB |) INA, OF NAL o ea! 323 
NE. x E____ 56 SE. x S____ 146 SW. x W__ 236 NW. x N__ 326 
NE. x E. Y% H_____ 59) | SSE: 34 He 2 227 149 | SW. x W. 14 W__ 239 | NNW. 34 W____- 329 
NE. x E. % B_--_- 62 | SSH. 1% E_______ 152 | SW.x W. 44 W___ 242 | NNW. “ Wee 332 
NE. x E. 34 E____- 65 | SSE. 144 E_______ 155 | SW. x W. 34 W 245 | NNW. 44 W_.__- 335 
BN eee 68 SSB 158 WSW____- 248 NNW_-___-_ 338 
JEINID, WA Wie 7D) || Si 5x 183 BA 1 160 | WSW. 144 W_____ 250 | N. x W. 34 W____ 340 
ENE, Y% Hoos WB \ Se se BE YG 163 | WSW. 4% W____- 253 | N. x W. % W___- 3438 
IBYNIE SZ He E76) Sto E yowe aes 166 | WSW. 34 W____- 256 | N. x W. 14 W____ 346 
1M, 3 Woes 79 Sh oe IW 169 W. xS____ 259 N. x W____ 349 
1B CAIN ng Se BO) SL A TOs NBN We 8A Ba 2 eset PX} NNT, BA ANE ee 352 
EUG IN aya 2 aes Sule SL WG We ee SL 7Asah lee Pal pene oe 264 ONG eae 354 
TH LAIN Se as ed CVA shi a dpaas Sse WA | Who 3A Sis cssseee ROY | ANG AA Wao ke soso! 357 
east of true north, and as west or negative if the deflection is west of true north. The 
magnitude of the variation usually differs considerably in different localities and also 
The amount of the variation in different 
localities is shown by compass roses on the charts published by the Coast and Geodetic 
Survey, which also include statements of the annual change. 
the true azimuth and magnetic azimuth may be expressed by the following formula: 
True azimuth=magenetic azimuth-+ variation of compass. 
35. Deviation of compass.—This term is applied to the error in a ship’s magnetic 
changes to some extent from year to year. 
compass arising from the attraction of the magnetic metal in the ship itself. 
The relation between 
If the 
magnetic needle is deflected to the right of the magnetic north, the deviation is said 
to be east or positive 
; if deflected to the left, the deviation is west or negative. 
The 
deviation applied according to sign to the compass bearing of an object gives its mag- 
netic bearing. Each compass on the ship may be affected differently and the deviation 
usually differs for each heading of the ship. Some compasses are compensated for 
deviation, but if this has not been done, a deviation card should be prepared showing 
the amount of error for different headings of the ship. 
In general practice the deviation 
