If a cone or sugar-loaf be cut through in certain directions, we shall
obtain figures which are termed conic sections: thus, if we cut through
a sugar-loaf parallel to its base or bottom, the outline or edge of the
loaf where it is cut will be _a circle_. If the cut is made so as to
slant, and not be parallel to the base of the loaf, the outline is an
_ellipse_, provided the cut goes quite through the sides of the loaf
all round; but if it goes slanting, and parallel to the line of the
loaf’s side, the outline is a _parabola_, a conic section or curve,
which is distinguished by characteristic properties, every point of it
bearing a certain fixed relation to a certain point within it, as the
circle does to its centre.--_Dr. Paris’s Notes to Philosophy in Sport,
&c._