OF LOGICAL CLASS-FREQUENCIES, ETC. 
121 
X -j- y z — oy — 0'5 (a) 
X y — z — q (/3) 
X -\- y + Z = q (y) 
~ X + y z = q (S) 
X + // + 2 — ^q ~ I'O (e) 
X + y - z^2q - 0-5 {'Q 
X y z =■ 2q — 0'5 [rj) 
~ X y z = 2q ~ 0‘5 [0). 
§ 28. Case (I)— 
(AB) [u) = (BC) (ic) = &c. = q = 0‘25 
All the attributes ABCIJ are independent pair and pair. 
The conditions of inferior congruence are 
X — 0 y ~ 0 z — 0 
X = 0-25 y = 0-25 2 = 0 - 25 , 
but do not come into account, the planes they re})resent only passing through tlie 
angles ABCDEB^ (tig. 10)'^' of the equilateral octahedron bounded by the [danes— 
* Figs. 10, 11, 12 are drawn to twice the scale of figures 1-5. 
VOL. CXCVII.—A. 
R 
