The explanation of the movement of an outer planet like Mars could also be deduced from the joint effect of two perfect motions.
Let us assume that this outer planet has started on its course, in a prescribed path, and that it has a certain mass.
For consider the facts which characterise the movements of an outer planet such as Mars.
Le Verrier's prediction of an outer planet was a matter of dead certainty.
We'd better make the limits of your sovereignty the orbit of the outer planet of this system.