LAWS OF DECREMENT. 385 



We first require the plane angles e f d, dfg> fig. 

 362, which may be thus found. 



sn. 



R -J/-COS. I (/ I +/ ? + f y ) COS. I (J t +/ 6 _/ 



si. in 



sin. J t sin. I 



R I" cos> $ (/i+-*7+*6) cos. | (/.+/, / 6 ) 

 sin. /! sin. 7 7 



But /, = 105 5' 



7 6 = 47 47' 



152 52'+ J 7 , 34 3' z=186 55', i of which 

 is 93 27' 30 



and ... 152 52' 34 3'= 11 8 49', | of which 



is 59 24' 30 

 Again /, r= 105 5 ; 

 I 7 = 3V 3' 



139 8'+/ 6 , 47 3 47'i=186 55' \ of which 

 is 93 27' 30" 



and .... 139 8' 47 47'= 91 2P,iof which 



is 45 40' 30". 



The preceding general formulae therefore become, 

 sin. I V e fd 



R 4 /cos. 93 27 7 30" cos. 59' 24 7 30 77 ~" 

 sin. 105 5' sin. 47 47' 



sin. J v <*fg = 



R 4/COS. 93 27' 30" cos. 45 40' 30^ 



sin 105 5' sin. 34 3' 



These equations may be resolved by the assistance 

 i in 



3c 



of the table of logarithms in the following manner. 



