  The swimming of a two-sphere system and of a three-sphere chain in an
incompressible viscous fluid is studied on the basis of simplified equations of
motion which take account of both Stokes friction and added mass effects. The
analysis is based on an explicit expression for the asymptotic periodic
swimming velocity and a corresponding evaluation of the mean rate of
dissipation. The mean swimming velocity of the two-sphere system is found to be
non-vanishing provided that the two spheres are not identical. The swimming of
a comparable chain of three identical spheres is much more efficient.
