Images of high-redshift galaxies distorted by gravitational fields of foreground clusters can sometimes form arcs, continuous or broken. The gross features of these arcs, namely the degrees of circularity and uniformity, the angular extents, and the widths, can be used to constrain the shapes of cluster gravitational wells. In the case in which an arc and a counterarc are seen, their angular extents can indicate whether the potential can possibly be approximated by a small quadrupole lens. If so, the ellipticity of the lens can be constrained, and it may be possible to discriminate between the large arcs which are single images and those which are triplets. The arcs in clusters A963 and 2244-02 can be reproduced by small quadrupole lenses, given the photographs published so far, whereas the recent B-R picture of cluster A370 seems to favor a more complex lens potential. It is possible to constrain a combination of the source galaxy shape and orientation and of the ellipticity of the mass distribution in the core of cluster A963. Unless the source galaxy is elongated with axis ratio less than 1:5 and is suitably oriented, the ellipticity of the major mass constituent is smaller than the reported ellipticity of the central cD galaxy. In the 2244-02 case, the small quadrupole model has mass centered off the center of light of the core. Other models for this case are found in a Monte Carlo search scheme restricted to some resemblance between the mass and light distribution, and a condition that there are no extra images except those hidden by the cluster galaxies. There are models in which the dense group of galaxies near the arc (group A) traces a deep potential well, either the only such well or one of the two deep wells in the cluster. There are also models in which group A traces a moderate or small addition to a dominant potential well centered away from the arc center. Some of the latter models imply that one of the small galaxies near the second dense group of galaxies (group B) is an extra image of the source of the arc. All the suitable models found have extra images hidden by cluster galaxies.