9 6 Mifcellanea Curio [a. 



the half Coefficient of the ("fourth Term) di- 

 vided by a a, the Square of the Lotus Re&um 9 



viK. A- — 4- 1 is inftead of iq in 



Caytejius\ Conftru&ion, from whence the Cen- 

 ter E is determin d. Then drawing a Paral- 

 lel to the Axis, at the diftance to the left 

 lide (becaufe of % si x A- \ b) whofe Interfer- 

 on with the Parabola, let be 6 ; a Circle de- 

 fcribed on the Center E with the Radius EO, 

 will cut or touch the Parabola in as many 

 Points as the Equation has true Roots, which 

 Roots,or ^,are the Perpendiculars let fall from 

 thofe Points upon the Parallel to the Axis, 

 the Affirmative ones to the Right fide, and 

 the Negatives to the Left, if the third or 

 fourth Term, or both, be wanting in the Equa- 

 tion, there's no difference at all ( of the Me- 

 «. thod of inveftigating the Central Rule) to be 

 obferv'd. But the Quantity p or q being want- 

 ing, thofe parts of the Lines CD and DE (in 

 fome manner deduced from that Quantity) 

 will be wanting too, and we are to proceed 

 with the other Coefficients of the third and 

 fourth Term in the new Equation, according 

 to the way prefcrib'd in the foregoing Exam- 

 ples. 



Hitherto we have confider'd Mr. Baker's 

 General Method, than which none more Ealle 

 and Expeditious is to be expected, ufing either 

 a Parabola, or any other Curve for a Conftru- 

 dion, when the Equation rifes to the Bi- 

 quadratick Power. For while I am writing 

 of this, 'tis my good Luck to hit upon a cer- 

 tain Geometric!^ Effeftion of the central Rule, 

 which is Expeditious beyond Hope, and will 



abun- 



