  Single molecule experiments on bacteriophages show an exponential scaling for
the dependence of mobility on the length of DNA within the capsid. It has been
suggested that this could be due to the "capstan mechanism" -- the exponential
amplification of friction forces that result when a rope is wound around a
cylinder as in a ship's capstan. Here we describe a desktop experiment that
illustrates the effect. Though our model phage is a million times larger, it
exhibits the same scaling observed in single molecule experiments.
