\title{ Dynamics of the Bar at the Galactic Centre}
\author{ Ortwin Gerhard}
\affil{Astron.Inst, Univ.Basel, CH}

\begin{abstract}

There is now substantial evidence for a rotating bar in the inner
Galaxy.  This is an important change in our perception of the Galaxy
because it changes the ways in which we have to think about its
evolutionary history.

The idea of a Galactic bar is not new; that motion on elliptic orbits
in a barred potential might explain various aspects of the atomic and
molecular gas observations near the Galactic Centre has been suggested
a number of times (e.g., Peters 1975, Cohen \& Few 1976, Liszt \&
Burton 1980, Gerhard \& Vietri 1986, Mulder \& Liem 1986, Sanders 1989).

What has changed in the past few years is (i) that the evidence now
comes from several fronts, including the NIR light distribution as
measured by COBE, IRAS source counts, atomic and molecular gas
kinematics, the first indications for triaxiality in the stellar
kinematics of the bulge, and perhaps the large optical depth to
microlensing in the OGLE experiment; and (ii) that there is a
dynamical model which provides a physical basis for explaining a
number of independent features in the observed gas kinematics, is
consistent to zeroth order with the other pieces of evidence for a bar
that we now have, and promises to be extendable towards including
these into one coherent picture.

In this review I give a brief summary of the current evidence for the
bar in the inner Galaxy. Then I discuss in more detail the subject of
gas flows in bars and in the Galactic Centre. The integrated NIR
photometry is described in the paper by Dwek.  Finally, several
evolutionary processes are briefly discussed which become relevant for
Galactic evolution because of the presence of the bar, such as gas
infall, angular momentum transfer, subsequent central star formation,
and the formation of peanut-bulge-like stellar systems from bars
through a bending instability.
\end{abstract}