22 in the preceding article, it will be seen that if the crank OH and the connecting HE are of equal length, any point on the latter or on its prolongation, except E, H, and F, will describe an exact ellipse.

Mars now appeared too slow at the apses instead of too quick, so obviously some intermediate ellipse must be sought between the trial ellipse and the circle on the same axis.

Draw a narrow ellipse, with this line as its major axis, and shade it.

If positive energy is along the shaded ellipse, negative energy is in each field beyondearth and sun.