  In general, the time of flight of a charged particle in an accelerator will
depend on the particle's transverse amplitude. This effect can become important
in machines with large transverse emittances, such as muon accelerators. We
will describe the effect, its physical origin, and the circumstances where it
becomes important. We will then demonstrate that the effect is directly related
to chromaticity. We will describe the effect on the longitudinal dynamics in
various circumstances, including linacs and fixed field alternating gradient
accelerators (FFAGs). We will describe methods for correcting the effect,
particularly in FFAGs.
