1915-16.] The “ Geometria Organica ” of Colin Maclaurin. 
The equation to the locus of Q is therefore 
dx^y - abx 2 + d(b - d)xy — ~ y 2 . 
Case XXI. 
I and V both perpendicular to 0 1 0 2 . 
Locus of Q, 
xy* + \ d x 2 + a = 0. 
b b — d b 
Fig. 12. 
Case XXII. 
I and V parallel to 0 1 0 2 ; l midway between V and OjOg. 
101 
( 1 ) 
Then 
0 2 A = a, 
0 2 B = 2a. 
Let the equation to 0 2 R be 
ty = x . 
Then R is the point (2 at, 2a). 
The equation to O x R is 
y x - d 
2a ^ 2 at - d 
(i) 
( 2 ) 
