  An experiment is proposed which can distinguish between two approaches to the
reality of the electric field, and whether it has mechanical properties such as
mass and stress. A charged pendulum swings within the field of a much larger
charge. The two fields manifest the familiar apparent curvature of their
field-lines, "bent" so as not to cross each other. If this phenomenon is real,
the pendulum's center of mass must be proportionately shifted according to its
lines' curvature. This prediction has no precise counterpart in the
conventional interpretation, where this curvature is a mere superposition of
the two fields' crossing lines. This empirical distinction, meriting test in
itself, further bears on several unresolved issues in classical, quantum and
relativistic electromagnetism.
