< y\£’ 
/ x 
\y 
{ah' — a'b, 
ac’ — ale , 
be' — b'c \x, y f, 
(?) 
(\a + fxa', 
\b “H fib , 
Xc + ¡id \x, yf, 
(8) 
(ac — b 2 , ac' 
2 bb' + cal, 
aid — b' 2 /if, 
(9) 
(1) and (2) are the quadrics, (3) and (5) are the discriminants, and (4) is the lineo- 
linear invariant, or connective of the discriminants; (6) is the resultant of the two 
quadrics, (7) is the Jacobian, (8) is an intermediate, and (9) is the discriminant of the 
intermediate. And where it is convenient to do so, I write 
(1) = u, 
(2) = U', 
(3) = □, 
(4) = Q, 
(5) = □ 
(6) = R, 
(?) = H, 
(8) = W, 
(9) = 0. 
c. II. 
67