CHAP, v.] USE OF THE SHIP FOR TRIANGULATION 147 



(3) In A D B C, given D B, C B, and Z D B C, find 

 Z « B D C, B C D, and D C. 



(4) In A D F C, given F D, F C, and Z D F C, find 

 Z « F D C, F C D, and D C. 



(5) Z BDC = BDF+FDa 



Compare B D C as found in (3) and take the mean. 



(6) Z BCD = FCD-FCB. 



Compare B C D as found in (3) and take the mean. Apply 

 convergencies to the true bearings of C and D from A and B 

 respectively. 



(7) Z A D B = difference between the reversed bearings of 

 D from A and B. 



(8) Z A C B = difference between the reversed bearings of 

 C from A and B. 



(9) Z EDF = ADB-(ADE4:BDF). 



(10) Z ECF-ACB-(ACE + BCF). 



Z FDC = BDC -BDF. Compare also with (4). 

 Z FCD = BCD+BCF. Compare also with (4). 

 Z D F C has been observed direct. 

 Test the triangle D F C. 



(11) In A D F C, given F D and all the angles, find C F, D C. 

 Compare the values of D C as found in (3), (4), and (11), and 



take the mean. 

 Compare the values of C F as found in (2) and (11). 



Z ACD = ACE+ECF + FCD. 



Z ADC = BDC-ADB. 



Z C A D has been observed direct. 

 Test the triangle ADC. 



(12) In A A D C, given D C and all the angles, find A C, A D. 



(13) In A A C E, find A E, C E. 



(14) In A ACB, given AC, C B, and Z A C B, find 

 Z « C A B, C B A, and A B. 



(15) In A ADB, given AD, D B, and Z A D B, find 

 Z « D A B, D B A, and A B. 



(16) Compare the values of A B as found in (14) and (15), 

 and take the mean. 



(17) Apply Z C A B to the true bearing of C from A, and 

 obtain the true bearing of B from A. 



(18) Apply Z C B A to the true bearing of C from B, and 

 obtain the true bearing of A from B. 



10—2 



