( 1032 ) 
Pig. 
The plane S cuts P (Ahl) according to the line FO; the mineral 
substance lies to the right of this secant-line, as is indicated by the 
hatching. If with a constant value of 6(6=6,), @ increases, then 
the angle A= ~ GOF, which for s (9,6) in the first octant 0 
Tea spit iy’ T ’ 
and < —, diminishes, till with 9 =— the value 4=O is reached 
2 AR 
-_ 
Now becomes / <0, obtains in the I'd octant a value — — ; with 
ah oe . : 341 
gG= 77 18 h=—a; in the IV™ octant the ‘value 4 = on 
amel 
surpassed; and at last with 9 = 22a h obtains the value — 2x -+ f,, 
in which fh, is the angle, that corresponds to e = 0, 6 = o9,. 
Fig. 2 represents the change of angle 4 for a plane V (¢ = 60°), 
