CHAP. XV.] TRUE BEARING 361 



Example. 



August 10, 1881, Lat. 43° 30' N., Long. 66° 30' W., at 

 13'' 34'" G.M.T. Observed angle from Polaris to Seal Island 

 light 80° 10', right of Polaris. 



h. m. ^ ' 



G.M.T. .. 13 34 

 Long 4 26 



M T. ship .. 9 08 

 Sid T. noon .. 9 16 

 Acceler. . . 2 



1st S. T. obs. 18 26 



+ 6 



2na „ „ .. 26 



CoiT. for 2ud S. T. .. 1° 1 7' 



Cos. ang. dist. 

 (Sec. Alt. 



Cos. hor. ang. . . . . 9-3698 



Hor. aug . . 76° 27' 



Polaris ., .. ..X. 1 45 E. 



Seal l^ L*. .. N.78 12 E. 



VARIATION. 



Accurate variations are very useful in all parts of the A\orld, 

 as from them the lines of equal variation shoA\n on charts are 

 drawn ; but to enable them to be so used, they must be trust- 

 Avorthy. 



Variations obtained by swinging the sliip carefully with a seaObser- 

 smooth sea, and in water of, say, over 50 fathoms, are most ^^^^o^^- 

 useful, as fear of local attraction is thereby removed. 



The bearing of the sun, or of an object sufficiently distant to 

 maintain the same direction whilst steaming round, and of which 

 the true bearing is obtained, should be observed on evenly dis- 

 tributed points. There is no necessity to observe more than 

 on every other point, and good results will be obtained from 

 the cardinal and quadrantal points. 



