One of us (A.R.D.) would like to acknowledge support from the Center for Fundamental
Materials Research during the summer of 1989 for a visit to Michigan State University. M.F.T.
would like to acknowledge support from the National Institute for Standards and Technology for
a visit during the Fall of 1989, during which much of the digital-image and lattice-needle work
was begun. The research at Michigan State has been supported by the Research Excellence Fund
from the State of Michigan. We would like to thank M.A. Dubson, C.J. Lobb, and J. Tobochnik
for useful conversations, and for supplying experimental and simulation data in digital form.