74 



A MANUAL OF TOPOGRAPHIC METHODS. 



The constants used are those of the Clarke spheroid of 1866. 



These formula? are derived and explained in Appendix No. 7, Report 

 U. S. Coast and Geodetic Survey for 1884. 



The following are examples of the use of the formulae, taken from the 

 triansrulation in New Mexico : 



Azimuth ;i 

 Spherical a 



Nell — Chusea. 

 Nell— Zuni. 

 Zuni— Nell. 



(lEoliETK' ('('ORDINATE*. 



LOiN'olTCDE. 



log. K 4. 6236305 

 " B 8.5111939 



" cos a' 9. 89:10500 



log (I) 3. 0278738 



log. K 2 9. 24726 



" C 1.25696 



" sin 2 a' 9.58986 



log. (II) 0. 09408 



log. D 2. 3679 



" [I + II] 2 6.0568 



log. (Ill) 8.4247 



log. E 6.0124 



" B?sin*a'8.8371 

 " (I) 3.0279 



log. (IV) 7. 8774 



(ieo. Pos. No. 6. 



A' 108 54 40.285 



Computation for longitude : 



log. K 4. 6236305 



" Sin a' 9.7949286 



" A' 8.5092394 



" sec. 1/ I). 0872944 



Corr. for ditr. arc. & sine = — 15 



log. (V) 3.0150914 



SK 1 <>:;.-. .360 



Computation of azimuth : 



m 



9. 761522 

 0. 000001 



2. 776614 



- 597". 876 



- 9' 57". 876 



Computation of Azimuth a, in Book ,\ 



Spherical angle and distance = K. in Book 

 Stat ion ; Computed by 



Triangle No. 



Azimuth a: 

 Spherical au.^lc 



5 a + 1 Hi » 

 Azimuth (a): 



Chusea— Nell. 

 Chusea — Zuni. 

 Zuni— Chusea. 



