CHAP. XV.] 



TRUE BEARING 



359 



required, which can be done by any of the applications of the 



formula 



Cos OS-Cos ZS . CosZO 



'Cos Z S = . 



Sin Z S . Sin ZO 



Example. 



(One observer with sextant, sea horizon, alternate observations, 

 object elevated.) 



At S. Ann's A, October 5, 1881, Lat. 5° 10' S., Long. 

 57° 14' E., the following observations were taken for true 

 bearing of Snow Peak. Height of eye 10 feet, object right 

 of O. M.T. place ^^ • 00'" I.E. - 50". 



Alt. Ql I -^^''S- Distance of 



Snow Peak (^ 



30 06 10 



13 00 



20 15 



28 00 



36 10 



42 50 



94 14 40 



16 10 



18 30 



20 00 



21 20 



Klevati'n of Snow Peak. 



On ari 

 Off ., 



H. E. 



1 22 13 



Mean. obs. alt. Q. 

 LE 



n. E. 



S. D. .. 



App. alt. 

 Eei. .. 



Tr. all. 



30 24 24 

 - 50 



6) 450-06 



Mean obs. ang. dist. 

 L E. 



S. D. 



Cuir. anir. dist. 



7' -30'^ 



O / II 



94 18 08 

 - 50 



94 17 18 

 + 16 02 



94 33 20 



