Experimental measurements of the exit time distribution during the batch discharge of a flat-bottomed cylindrical bunker show good agreement with the predictions of the kinematic model of Litwiniszyn (1963, Bull. Acad. Pol. Sci. 11, 61-70) during the early stages of discharge. During the later stages, the descending top surface overtakes the particles at large distances from the centreline and transfers them to the fast-moving central core with the result that they are discharged sooner than predicted by the kinematic model.