98 On the Trigonometrical Survey 



In like manner the bearing of Brown Mountain is cal- 

 culated from each of the other observations at the 

 Dromedary with the following results : — 

 Results of Eastern Elongations. Eesults of Western Elongations. 



aCrucis ... 110 36 50-4 



Ditto ... 110 36 46-7 

 »j Argus... 110 36 54-0 



Ditto ... 110 36 50-8 



Ditto ... 110 36 54-0 „ ^ ^ 



a Argus... 110 36 36.4 110 36 SS'l 



Ditto 110 36 32-2 



/3 Centauii 110 36 11-9 

 a Eridani 110 36 58.6 



Means... 110 36 43.6 110 36 41-3 



Mean of all S. 110° 36' 42*4 E. 



At Brown Mountain the bearing of the Dromedary from 

 three Eastern and four Western elongations is — 



S. 69 6 25-2 W. 

 Convergence of Meridians 16 42*4 



69 23 7-6 

 180 00 



S. 110 36 52-4 E, 



f Bearing referred to the 

 ( meridian of Dromedary. 



S 110 36 42-4 f Do. do. from observations 



\ at Dromedary. 



10-0 Difference. 



The convergence of the meridians of the different stations 



has been computed by the formula 36549 '2 Cos. Lat. — 305'8 



Cos. 3 Lat. -f" ^ Cos, 5 Lat.= length of 1 degree of parallel 



at the latitude of the Station, (their difference giving the 



convergence in feet due to the difference of latitude), and 



Convergence in feet rr, e ^ n 



-=-v,5; g, ^.^ -1 . ,. ^ = Tan. of angle of convergence 



Difference oi latitude in leet 



or at once by the formula, 



.Z'- z= 180 — 2£ X d. Sin. z Sec, I Sin. 4 (^ + Sec. I {h—l) 



a 

 where Z and z are the azimuths at the two extremities of the line 

 from Station to Station. 

 L. 1. Their latitudes, 

 a Earth's radius in feet, 

 d Distance or length of line in feet. 

 20 206264-8 seconds. 



