  The next generation of particle edm searches will be at such a high
sensitivity that it will be possible for the results to be contaminated by a
systematic error resulting from the interaction of the motional (E x v/c)
magnetic field with stray field gradients. In this paper we extend previous
work to present an analytic form for the frequency shift in the case of a
rectangular storage vessel and discuss the implications of the result for the
neutron edm experiment which will be installed at the SNS (Spallation Neutron
Source) by the LANL collaboration
