A Body, of a convex Surface, terminating on another Body, of the same Colour with the first, the Term or Contour of the convex Body, will appear more obscure than that of the other Body, on which it terminates: With regard to flat Surfaces, their Term will appear obscure, on a White Ground, and on a Dark Ground, it will appear brighter, than any other part of the Surface; even though the Light wherewith it is illumined, have an equal force on every part.