PROFESSOR CAYLEY’S TENTH MEMOIR ON QUANTICS. 
661 
S,= a 3 . 0 
+a 2 {&(0c+0)+6°(0c 3 +0c 3 +0c + 0)} 
+a {6 3 . 0+6 2 (0c 2 +0c+0)+6(-9c 4 +36c 3 — 54 c 2 +36c— 9) 
+6°(36c 5 -l71c 4 +324c 3 -306c 2 +144c-27)f 
+a°{6 4 (0c+0)+6 8 (7c 3 -21c 2 +21c— 7)+6 2 (— 39c 4 +135c 3 — 171c 2 +93c— 18) 
+ 6(66c 5 -243c 4 +333c 3 -201c 2 +45c) 
+ b°( — 27c 7 +101c g — I41 c 5 + 87c 4 — 20c 3 )} 
which for c=l becomes =0. 
It follows that for c=d=e=f= 1, the value of the covariant S is =2(6 — l)he 3 , which 
might be easily verified. 
