12 SCIENCE ABSOLUTE OF 



what precede*) PSH * both to HX and to CP. 

 and BO also UN I! ^CP. 



11. Consider tin- aggregate of the point 

 A, and all points of which any one B is such, 

 that if UN II AM, also BN^AM; call itF; but 

 the intersection of P with any plane contain 

 ing the sect AM call L. 



K has a point, and one- only, on any straight 

 II AM; and evidently L is divided by ray AM 

 into two congruent parts. 



Call the ray AM the axis of L. Evidently 

 also, in any plane containing the sect AM, there 

 is for the axis ray AM a single L. Call any 

 Lot this sort the L of this ray AM (in the 

 plain- considered, being understood). Kyi- 

 dent ly by revolving L around AM we describe 

 the Fof which ray AM is called the axis, and in 

 turn F tna y be ascribed to ///&amp;lt; axis ray AM. 

 I?) 12. It&quot; 1&amp;gt; i&amp;gt; anywhere on the L of ray AM, 

 and UN II* AM (11); then the L of ray AM 

 and the L of ray BN coincit/e. For suppose, 

 in distinction, L the L of rav UN. . Let C be 

 an v where in L . and CP H -BN (1D- &&quot; 

 BNH ^AM, so CPU *AM U ini, and so C also 

 will fall on L. And if I is any where on L, and 

 CPII^AM: thenCPH^BN (10); and C also 

 falls on L (11). Thus L and L are the 



