JSiifceHanea Curt of a. 



abundantly fatisfy thofe that are curious in 

 thefe Matters. 



(Fig. 10. ) Having defcrib'd the Parabola 

 NAM, whofe Vertex'is A, Axis ABC, and Pa- 

 rameter a ; let the Equation be reduced to this 

 Form, £. 4 . apz?i aaqiL. a % r. — o- 0 of 



if it be only a Cubical one, to this, z, 3 . bz z . 

 *pz,. aaq. = o. Then at the diftance BD==^, 

 Jet DH be drawn parallel to the Axis (to the 

 Left Hand if it bc-^, and to the Right, if 

 it ht^vb) meeting the Parabola in the point 

 X>, from Whence let fall BD .perpendicular 

 to the Axis. In the Line A B continued to- 

 wards make B K— i *, and draw the Line 

 DK interminate on either fide. Farther, 

 take KC=2AB, always in the Axis produ- 

 ced beyond Ki> and if the quantity p has 

 the Sign *4 , take towards the fame parts, 

 C E=2 />, but towards the contrary part, if 

 it be ~b/>. Then at the point E (but at the 

 point C if the quantity be wanting) ereft 

 EF perpendicular to the Axis, meeting (if 

 need be) the Line DK produced, in the 

 point F, which point is the Center of the 

 Circle required, if the quantity q be want- 

 ing. But if q be in the Equation, then we 

 putt take in the Line F E (if need be) pro- 

 duced the length of FG=f#, which place 

 to the Left Hand if it be "V q, but to the 

 Right if it be q ; and then the point G 

 will be the Center of the Circle required for 

 the Conftru&ion, and the Radius of it, will 

 be the Line G D, if the quantity r be want- 

 ing, that is, if the Equation be only a Cubi- 

 cal bne^ the Square of which fame Line (in 

 fel^mdratick Equations) 1$ to be eiicreafed 



H by 



