An oval is never mistaken for a circle, nor an hyperbola for an ellipsis.
If the cone is cut off vertically on the dotted line, A, the curve is a hyperbola.
I said, "if my orbit is a hyperbola, I shall never return to earth."
The curve is in this case called an Hyperbola (see fig. 20).
In the hyperbola we have the mathematical demonstration of the error of an axiom.