  We report sets of precise and reproducible measurements on the static
pressure at the bottom of a granular column. We make a quantitative analysis of
the pressure saturation when the column height is increased. We evidence a
great sensitivity of the measurements with the global packing fraction and the
eventual presence of shear bands at the boundaries. We also show the limit of
the classical Janssen model and discuss these experimental results under the
scope of recently proposed theoretical frameworks.
