390 APPENDIX CALCULATION OF THE 



We require the plane angles dfe, and dfg, which 

 are evidently less than d e^and d g f. 



1. To find the angle dfe, from the formula 



tang, i d = d> tan - 



s 



we have df-\-de = 4 + 2 = 6 

 <// de = 4 2 = 2 

 and | the sum of the unknown angles=392'30" 



therefore tang. * d = 2ta "S- 39 2>3 " 



6 



log. 2 . . . . = 0-3010300 

 log. tang. 39" 2' 30" = 9-9090149 



102100449 

 loff. 6 = 0-7781513 



long. tang. \d . = 9-4318936 



Therefore | the difference of the unknown 

 angles zn 15 7' 38" 



and consequently V4A = 39 ' 2/ SO 77 15 7 ; 38 /; 

 =23 54' 52". 



2. To find the angle dfg, 



we have df-\-fg 4 + 3 = 7 

 dffg =4 3 = 1 

 and } 5 as before = 39 2' 30'' 

 therefore tang. -| rf ^ tang. 39 2' 30' 7 



log. tang. 39 2' 30" = 9-9090149 

 log. 7 . . . . = 0-8450980 



log. tang, i rf . . = 9-0639169 



therefore | df = 6 36' 31" 



and v </=392'30"=636 / 31' / =3225' 59 ;/ . 



