  As a preparation for its quantization in the loop formalism, the
2-dimensional gravitation model of Jackiw and Teitelboim is analysed in the
classical canonical formalism. The dynamics is of pure constraints as it is
well-known. A partial gauge fixing of the temporal type being performed, the
resulting second class constraints are sorted out and the corresponding Dirac
bracket algebra is worked out. Dirac observables of this classical theory are
then calculated.
