  By distinguishing the main arc Fraternite from the minor arcs Egalite (2,1),
Liberte, Courage, the restricted three-body system is extended to a
non-conservative restricted four-body system with the central body Neptune S,
the primary body Galatea X, a minor body Fraternite F, and a test body s.
Through the equations of motion, it is shown that the locations where the force
is null along the orbit of s correspond to the locations of Egalite (2,1),
Liberte, and Courage. Even if all the arcs were captured by CER sites
initially, the orbits over the CERs would be unstable for the minor arcs due to
the disturbing force of Fraternite, allowing them to be relocated to the null
points. On the other hand, the minor arcs do not have the mass to destabilize
Fraternite from its CER site, which is enlarged from 8.37 degrees to 9.7
degrees thus accounting for the Fraternite's span. In this restricted four-body
system, s is under the effects of the potentials of X and F. The potential of X
drives a long period harmonic pendulum oscillation of $(n+1)\theta_{s}$ of the
test body s with respect to $n\theta_{x}$ of X centered over a local CER site
with period $T=1,000\,d$, while the potential of F drives an even longer period
singular pendulum oscillation centered over Fraternite with period
$T_{f}=40,000\,d$. It is shown that the null points are the turning points of
the harmonic CER oscillation, and the non-conservative nature of this system
could account for the time varying intensity, configuration, and disappearance
of the minor arcs.
