EXTINCTION ANGLES. 
.30 ' 
45' 
.2030' 
15' 
0' 
.10 
.0 
88' 
89' 
90 
91 
92" 
FIG. 76. This differs from Figs. 74 and 75 only in the value of K, which is J. Curves 
calculated from the formula 7\ = J[2-j-cos 2<+cos 2 (<j> 26)]. The heavy curve from 
the formula = , 7, = }(i cos 
2 
.20 
45 
30' 
13' 
0' 
.10 
.0 
88' 
89' 
91* 
FIG. 77. Differs from Fig. 76 only in K, which is J. The curves are expressed by the 
formula /, = J [4+3 cos 20+cos a(0 28)] and the heavy curve by 7, = J(i cos 40). 
