  The model first introduced by Raga & Canto (1996) in which astrophysical jets
are deflected on passing through an isothermal high density region is
generalised by taking into account gravitational effects on the motion of the
jet as it crosses the high density cloud. The problem is also generalised for
relativistic jets in which gravitational effects induced by the cloud are
neglected. Two further cases, classical and relativistic, are discussed for the
cases in which the jet is deflected on passing through the interstellar gas of
a galaxy in which a dark matter halo dominates the gravitational potential.
  The criteria for the stability of jets due to the formation of internal
shocks are discussed.
