The charged-particle multiplicity distributions in different limited rapidity windows obtained in hadron-nucleus scattering at 200-360 GeV are examined using a model built from three general ideas: the geometric model, thermodynamic concepts, and independent emission of charged pairs. The model fits the data very well, especially for the distribution of negative charges, which does not suffer from contamination by protons evaporated from the nucleus. A central ingredient in the thermodynamic concept is the conservation of momentum in the collision of the beam hadron with an effective target, the latter being a tube of $\ensuremath{\sim}\ensuremath{\nu}$ particles. It is suggested that all dynamical models with $\ensuremath{\sim}\ensuremath{\nu}$ collisions and conservation of momentum would give similar results, and that this is the reason for the sucess of different dynamical models applied to this problem.