  The study of the $\gamma^* N\rightarrow \Delta$ reaction presents the best
quantitative method to explore the deviation of hadron shapes from spherical
symmetry (nonspherical amplitudes). Significant non-spherical electric (E2) and
Coulomb quadrupole (C2) amplitudes have been observed with good precision as a
function of $Q^2$ from photon point up to $\approx 7 ~(GeV/c)^2$. Quark model
calculations for these quadrupole amplitudes are at least an order of magnitude
too small and even have the wrong sign. Lattice QCD, chiral effective field
theory, and dynamic model calculations which include the effects of the
pion-cloud are in approximate agreement with experiment.
