Page:The Analyst; or, a Discourse Addressed to an Infidel Mathematician.djvu/42

32 XXI. In order therefore to clear up this Point, we will uppoe for intance that a Tangent is to be drawn to a Parabola, and examine the progres of this Affair, as it is performed by infiniteimal Differences.

Let AB be a Curve, the Abcie AP = x, the ordinate PB = y, the Difference of the Abcie PM = dx the Difference of the Ordinate RN = dy. Now by uppoing the Curve to be a Polygon, and conequently BN, the Increment or Difference of the Curve, to be a traight Line coincident with