( 1*2 ) 
that the three Poles 
are C, S and D, and 
that Lines or Rulers 
C R, S Qj Qt D R, 
revolve about thefe 
Poles. The Line 
which revolves a- 
bout D, ferves only 
to guide the Motion 
of the other two, fo 
that its Interfe&ion 
with each of them being carried over a fixed Right 
Line, their Interfe&ion with each other defcribes 
the Locus, which is Ihewn to be a Conick Section. 
The Interfe&ion of QD R with S Q, is luppofed 
to be carried over the fixed Right Line AF; the 
Interfe&ion of the fame QD R with C R, is fup- 
poled to be carried over the fixed Right Line A E 5 
and in the mean time, the Interfe&ion of the Right 
Lines S Q, C R, that revolve about the Poles S and 
C, defcribes a Conick Section. 
This Conick Se&ion pafies through the Poles 
C and S ; and if you produce D C and D S, till they 
meet with A Q and H R in F and E, it will alfo 
pafs through F and E : It alfo pafles always through 
A the Interfedtion of the fixed Lines QF and ERj 
from which this eafy Method follows for drawing 
a Conick Section through five given Points. Sup- 
pole that thefe five given Points are A, F, C, S and 
E : Join four of them by the Lines A F, F C, A E, 
E S, and produce two of thefe F C, E S, till they 
meet, and by their Interfedhon give the Point D; 
Suppofe infinite Right Lines revolve about this 
Point 
