  The X-ray holes at the centre of the Perseus Cluster of galaxies are not all
at the same position angle with respect to the centre of the cluster. This
configuration would result if the jet inflating the bubbles is precessing, or
moving around, and the bubbles detach at different times. The orientations
which best fit the observed travel directions are an inclination of the
precession axis to the line of sight of 120 degrees and an opening angle of 50
degrees. From the timescales for the bubbles seen in the cluster, the
precession timescale, t_prec, is around 3.3x10^7 yrs. The bubbles rising up
through different parts of the cluster may have interacted with the central
cool gas, forming the whorl of cool gas observed in the temperature structure
of the cluster. The dynamics of bubbles rising in fluids is discussed. The
conditions present in the cluster are such that oscillatory motion, observed
for bubbles rising in fluids on Earth, should take place. However the timescale
for this motion is longer than that taken for the bubbles to evolve into
spherical cap bubbles, which do not undergo a path instability, so such motion
is not expected to occur.
